KIKKEN Lab. 医療系専門学校レベルの生理学・解剖学の基礎をおもいっきりゆるいアニメーション/イラストレーションでまじめに紹介するサイト。 Workshop on Basic Human Biology Education for the paramedical school beginners' course, Japan Fri, 08 Nov 2019 00:16:44 +0900 en-US hourly 1 KIKKEN Lab. 32 32 126594771 [055] Voltage-dependent sodium channel (rev) (GB#113A02B) Mon, 05 Feb 2018 12:44:38 +0000 Na-channel

Although this site has not yet accessed as a whole, in that time (2017), ‘[024] voltage – dependent sodium channel ‘ page access somehow protruding. Very thankfully, on the other hand, there has been a part that is not accurate in the part of animation, and it is uncomfortable to leave it alone for the time being (is there an “accuracy” in the animation of this site in the first place? (^ ^)), so I finally decided to redraw back after four years.

However, it is a story of details, so people who do not mind the difference can be skipped. Nevertheless the voltage-dependent sodium channel animation of this page is the latest version (revised version).

● The switch of the channel is positive (apparent)

In the voltage-dependent channel, the specific part with electricity in the molecule moves according to the potential difference inside and outside the cell membrane in which the channel is embedded. That is the switch to open and close the gate. The principle is simple, the same polarity repel each other, different polarities attract each other. In the previous version of the page [024], I was thinking that the actual situation would not be understood well, so I assumed that this switch was a particle with a negative charge and drawn animation. However, when examined afterwards, although information was not yet found in the sodium channel, it seems that there is almost no doubt that at least in the voltage-dependent potassium channel, the gate is a positively charged particle ( Gate / Brain Science Dictionary ) . (To be precise, the potential sensor for moving the gate is positive particles.)

So in the picture of the sodium channel, using the known information, for the time being, the gate switch should be drawn with positively charged particles. So, the revised latest version is the animation of this page.

voltage-gated sodium channel
Since negatively charged particles are replaced by positively charged particles, the movement of the particles with respect to the membrane potential is opposite to that of the case of negative charged particles. With negative resting membrane potential inside the cell, the switch faces inward and moves outward when depolarized.

In addition, the movement of the switch, the timing of opening and closing the gate, and the movement of the ion are slightly revised. Nonetheless, there are few people who are aware of this, even if they look at it.

○ Referenced site

· Gate / Brain Science Dictionary (2013/8)
voltage-dependent channel/ Brain Science Dictionary
· Voltage Gated Sodium Channels / University of Washington

○ Related articles

[024] Voltage-dependent sodium channel
[021] Action potential
[031] 興奮伝導 conduction of excitation
[028] Resting membrane potential
[036] Ligand-gated ion channel
[044] 伸張反射 stretch reflex
[019] アデノシン三リン酸（ATP) adenosine triphosphate

○ Referenced books


rev.20171222, rev.20171223, rev.20171227, rev.20180105, rev.20180106, rev.20180228, rev.20190928.

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[054] Switching of the airway and esophagus (GB#105A04) Thu, 31 Aug 2017 13:19:58 +0000 swallowing 嚥下

● Understanding swallowing

Personal speed of understanding and learning is used be expressed such as “good” or “bad swallowing” in Japanese. The mechanism of the actual swallowing itself, however, is not likely to be easy to “swallow”. Actually, on the way to this path, a wide passage leading to the lung is open, and it requires a fairly sophisticated trick to pass foods and drinks beyond this.

●swallowing action called 嚥下

Swallowing is called “嚥下, En-ge” (swallowing / deglutition) in Japanese technical terms. Although it seems that it is not a mistake when reading on the net as a general term as “EN-KA”, it may not be able to communicate in the medical field. When eating foods, before the swallowing, there is an action called “咀嚼, So-shaku” (chewing / mastication) that chews or grinds.

In “So-shaku” and “En-ge”, it is strange to use a difficult language as a noun in Japanese, even though there is no letter of the verb, “噛む, to chew” or “呑み込む, to swallow” in it. With regard to “喉, No-do” (throat), “咽頭, In-tou” (pharynx) and “喉頭, Ko-tou” (larynx) are coming out. The word “口, Kuchi, mouth” is very simple kanji, but is there any special meaning that kanji that is hard barely rampant around the mouth?

●Swallowing at least three stages of flow work

process model swallowing
Aside from that, even if you swoop out only, there are at least three steps in its movement. First of all, you need to feed what you are eating from the mouth (“口腔, Ko-ku”, oral cavity) to the throat entrance, pharynx. Here, the work of the “舌, Ze-tu” (tongue) is important, it is called “Ko-ku stage” (oral stage). It is a voluntary movement that you can start with your own will, which will also be a signal to swallow from now.

The “In-tou phase” (pharyngeal stage) in which the passing food and drink (let’s call it a passing object here) pass through the throat part and finally the throat , descending from the esophagus (esobugus, esophagus) with a peristaltic movement “Shoku-dou phase” (esophageal stage), in order, the passage is sent to the stomach. Pharyngeal phase and esophagus phase proceed in arbitrary order according to the sequence and progress in the medulla oblongata of the brainstem. It is a reflex movement with the center.

● Switch the connection between the nose and mouth for the soft palate


As you open your mouth, you can see a fold hanging uvula. This is a soft palate made of muscle, and the behind it is the pharynx. The pharynx is divided into three parts, upper, middle and lower, saying the wider part from the back of the nasal cavity to the lower part just before the esophagus.

The wall of the throat which opens its mouth and looks deep is the wall of the mesopharynx / oropharynx. In English it seems to be more often called the pharyngeal oral part (oropharynx). The invisible part hidden behind the soft palate is the nasopharynx. At the time of swallowing, the soft palate serves to block the oropharynx and the nasopharynx so that the passing material does not get into the nasopharynx.　

● The larynx is open in the back of the pharynx, the esophagus is not open

The tongue visible when opening the mouth is like the tip of the iceberg, the tip of the mass of the large tongue muscle, the root of the tongue extends to the back of the pharynx . From the table there is a small upward facing upward look like the tip of a shoe vera beneath the tongue tonsil (lingual tonsil) at the base of the tongue muscle behind it that requires special equipment. Beyond that, wide cavities are open, but it is not the esophagus but the entrance to the trachea leading to the lungs, the part called the larynx.

The larynx is a rugged tube based on thyroid cartilage and cricoid cartilage (cinnabar ring, cricoid). On top of that is called the epiglottis, which will become the laryngeal lid. This epiglottis to the esophagus hits the hypopharynx. At this time, the entrance of the esophagus that should be lined with the larynx can not be seen anywhere.

In many explanatory figures, the esophagus is an image drawn in the form of a tube, but the esophagus except at that time just swallows things, has collapsed between the cricoid of the larynx and the back spine, and as a tube it is not open.

From the stereoscopic viewpoint, the hypopharynx becomes a shape that the tip of a thick tube called the larynx projects obliquely from the outside on the side of the round bottom of the acupuncture point of the pharynx. The incision of the cylinder is oblique so that the top will come off, and the sharp jump out is the epiglottis.

● Pharyngeal beginning, flow of hyoid bone and tongue muscle

swallowing-f10At the end of the oral period of the swallowing exercise, after the passing material reaches the oropharyngeal wall, it is switched to roughly automatic driving afterwards.

At the base of the tongue muscle, a small bone called a hyoid bone is buried. Since no bones are making joints, in studying osteology it was as though the impression was thin and forgotten, but besides the tongue muscles, the lower jaw, the throat and the shoulder it is one of the important parts that various streaks from are connected and it is indispensable for swallowing.

At the beginning of the pharyngeal phase, as the hyoid bone is drawn from the fixed position to the front of the jaw, at the same time, the root of the tongue makes a hard aneurysm (hump) and moves downwards so as to follow it, together muscle wall muscles perform peristalsis by control of the medulla oblongata and flow into the oropharynx , sending the thing that has come toward the hypopharynx.

● Late half of pharyngeal phase, epiglottis with protrusions with core


The central part of the epiglottis contains a core made of flat elastic cartilage called epiglottic cartilage. If I have such a positive upside, I am worried that it will become an obstacle when swallowing. However, when swallowing, this epiglottis inverts to the pattern and downwards and plays the role of a shield that prevents the entry of passing objects into the larynx.　

The upper half of the oblique incision of the hose is bent and it covers the opening of the incision. When the passing object passes, it returns to the original shape immediately with the pattern again. If there is no core, this will not work.

Depending on the drawing of the textbook, it seems that passing objects push down the epiglottis by themselves, but in fact it is more elaborate and it seems that this is the event that becomes the biggest point of swallowing.

● Later in the pharyngeal phase, the larynx is a close-by battle discard


As the passing thing falls down the oropharynx at a stretch, it is serious when entering the trachea, so the larynx must protect the larynx so that it does not get through.

Normally, in such a case, we think that the entrance should close the lid all the time, or if you move the entrance, you may think about a mechanism that keeps the lid apart as if to escape from the approaching one. However, the place where the larynx is daring to pass through things is daring. The thyroid cartilage surrounding the entrance of the larynx and the hyoid bone are connected by a thyrohyoid muscle, and while the hyoid bone moves forward, the thyroid cartilage is pulled up at once to the trachea following it.

How does this relate to swallowing? Actually, the root of the epiglottic cartilage which protruded to the pharynx extends far to the front wall of the thyroid cartilage and the root is fixed like a hinge. In the latter half of pharyngeal phase, the epiglottis is pressed down from the top of the tongue base and at the same time when the thyroid cartilage is lifted, the epiglottis rapidly rotates so that the crown faces downward with the base of the tongue as the fulcrum. It is supposed to be swallowing from the top to the bottom, but “Midgette” rise nostalgically, it was such a trick in the back.

If the switching delayed even for a moment, there is a danger of sucking in the passing object, but it is probably a way of discarding to save as much time as possible for closing the lid. And unfortunately, it is also a weak point that sometimes it will fail if you get old.

● Esophagus is opened by laryngeal movement


In the latter half of the pharyngeal phase, toward the anterior hyoid bone, the larynx is pulled out forward as it lifts. Then the entrance of the esophagus, which had been crushed behind the larynx, was pulled and spread out. When the passing object is guided around the lidded larynx to enter the entrance of the esophagus, it will be pressed toward the stomach by peristalsis of the automatic movement of the esophagus.

When passing through the esophagus, the esophagus is hard to spread in the part of the robust cricoid cartilage, but after passing it it is only the smooth muscle wall behind the trachea along the esophagus, the esophagus conveys the passing material while comfortably bulging.

By the way, the pharyngeal muscle is a striated muscle, and the esophagus is not a smooth muscle around the larynx but it is made of striated muscle. So it is a reflex movement by control of the medulla oblonga, even though it is automatic exercise, as it gets closer to the stomach it changes to smooth muscle and from the lower third of the esophagus it becomes only smooth muscle just like the digestive tract beneath it. Really, I am impressed that it works well.

● Things to eat chewed are gradually sent to the pharynx

process model swallowingThe above setup is basically the flow when swallowing things at once, When swallowing while eating like rice, it seems that they are taking a way to swallow at a stroke where they accumulate to a certain extent while sending them to the oropharynx little by little. Where to store it, the larynx is a tube that jumped out to the key point called the pharynx so that you can afford to some extent the part that hits the bottom of the cylinder around the cylinder.

In particular, there is a deep depression as the name of epiglottic vallecula between epiglottic spatula and tongue base, and the mouth of the esophagus is not opened, but both of the tube of that part. The side is a pear shaped depression (piriform sinus), which is a baglike structure, and usually it is supposed to swallow saliva after accumulating to a certain extent. When chewing is accompanied, it seems that the reflection is temporarily suppressed so that a swallowing movement does not occur automatically even if solid passing substance touches the oropharynx.

● Can not swallow and breathe simultaneously

As apparent from the complicated mechanism as described above, breathing is blocked because air can not enter and exit the pharynx during swallowing. In the middle of the larynx, there is a fold called vocal cords used when giving a voice, which closes tightly during swallowing and also plays a role of a shutter that does not pass passing objects by mistake.

In addition, control of the central nervous system, breathing exercise is temporarily suppressed in swallowing. Try swallowing while sounding the vocal cords. you find it impossible to keep on telling your voice no matter how hard you try.

Also, swallowing is easy while exhaling, but it is a little difficult while breathing in. It would be a worry to reduce the risk of accidental inhalation. It is easy to fail to swallow while sucking in. Since it works only in this complicated system, it is also unlikely that if something wrong happens, especially if you fail to control nerves it will cause aspiration.

● Nasal breathing and mouth breathing

Even when opening the mouth and looking at the back of the throat, the soft palate is raised to what mind and is blocking the nasopharynx. Even if you breathe like this, air should not come in and go out of your nose, as you can see by touching the hole in the nose.

Conversely, if you try to breathe in your nose with this nose, the soft palate will immediately descend and at the same time the tongue base will also be lifted, blocking the entrance and exit of the air from the mouth to the pharynx. When trying to open the entrance and try to lower the tongue base, the soft palate also lifts and this time the entry and exit of air from the nose is blocked. Apparently, it is not allowed to have both nasal breathing and mouth breathing at the same time.

● Dog breathing

Dogs have rumors that they can not breathe mouth. Unlike humans, because the soft palate is extending to the epiglottis (which is certain), the path of air through the nose and the path of food through the oral cavity are almost separated. It certainly seems that it is also possible to drink water while breathing in his nose. Then, what is the dog doing ha ha? That dog does not sweat, so it is said that he is doing it for divergence of body heat instead.

That’s right. However, is not the air coming in and going out of the respiratory tract, is it stopped only by the oral cavity and pharynx? I can only see the lungs moving together, and if that is not breathing, is breathing done separately from the nose? Breathing deeply with their nose while ha-ha with mouth, it feels like a tricky difficulty. First, when they bark, it seems that thy are calling out from their mouth using the vocal cords. Of course, at that time it is certain that the mouth and the airway are connected, so it is strange that they can not breathe in their mouth. I can not find clear answers on the net. I would like the veterinarian to properly explain it.

● Dolphins can not breathe in their mouth

On the other hand, dolphins and whales know that they can not breathe in the mouth due to their structure. The larynx cylinder extends long and passes through the pharynx into the nasal cavity because it fits snugly into the body, air can enter and exit exclusively through the nostrils.

It is well known that the mysterious hole that opens at the top of the dolphin head is a dolphin’s nose hole. It is functional because breathing can be done just by putting out the forehead on the sea surface, but there are few people who are conscious of being too conscious of being overwhelmed when closing that. In fact, there are also examples of poor whales that fish caught in the back of the nasal cavity and suffocated.

The reason why the fish is clogged is that the laryngeal cylinder is not integrated into the nasal cavity, so it seems that the fish swallowed from the mouth as a prey entered into the gap. If the mouth and the airway are separated, it is functional as it is not necessary to stop breathing while eating, but there are unexpected weak points.

Speaking of another weak point, when the mouth and breathing are separated, I think that they can not feel the flavor of things put in their mouth. We sometimes find dolphins that have swallowed plastic bags I guess that might be the reason . Even if it is not a dolphin, mammals other than humans, including dogs, tend to be able to drink and eat while breathing, so it may be the same that the flavor is hard to understand.

Instead, in most animals the nostrils and mouth are in close proximity, sniffing before eating. Dolphins may have sacrificed important things because they separated their nose and mouth.

Humans feel the flavor of various foods thanks to the crossover of the mouth and the respiratory tract, and I feel fortunate that I can live even if my nose is clogged.

○ Referenced sites

咽頭の臨床解剖,　吉原俊雄 著, 2008.
嚥下機能にまつわる昨今の生理学的知見,　井上 誠, 2012.
CGにより嚥下を見る,（特定非営利活動法人 嚥友会）
プロセスモデルで考える咀嚼嚥下リハビリテーション, 松尾 浩一郎, 2015.
嚥下アニメーション「咽頭の解剖生理 / 咀嚼嚥下の一例 （内視鏡検査視線）」-舌根-咽頭後壁間の接触を透明化-
嚥下機能の学習, by JA北海道常呂厚生病院
Scientists Discover a Mouth-Breathing Dolphin, 2016.
イルカが食べたごみ；NHK for School

○ Related articles

[046] Digestion and metabolism
[022] 胃と十二指腸　the stomach and the duodenum
[009] 筋収縮の伸縮幅　the range of muscular contraction
[035] 骨格筋収縮の張力 tension of the skeletal muscle contraction
[005] Peristalsis
[012] 分節運動　intestinal segmentation　
[033] 平滑筋の収縮 smooth muscle contraction
[003] Diaphragmatic breathing
[015] 胸式呼吸　costal breathing
[010] 肺胞換気量と死腔　alveolar ventilation and dead space
[049] A neural circuit for voluntary movement
[044] 伸張反射 stretch reflex

○ Referenced books


rev.20170902, rev.20170909, rev.20170929, rev.20180103, rev.20180211, rev.20190929.

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[053] Acetylcholine receptors (GB#114B03) Fri, 09 Dec 2016 08:35:45 +0000 acetylecholine receptors ●Not necessarily one keyhole to match


● Acetylcholine binds to cell membrane receptors


●Receptors are distinguished by agonist’s effectiveness



● Acetylcholine is a three-dimensional object



ACh binding siteM binding site

● Quite different mechanism of N receptor and M receptor




● Several small types of receptors



● The response of cells by N receptors is fast

nicotinic receptor


● Slow cell response by M receptor

muscarinic receptor


● Receptor at the right place



● Antagonizing substances are also different



● Neither agonist nor antagonist is easily degraded


● No functional meaning to the structure of transmitter


○ Referenced sites

Muscarinic acetylcholine receptor，Wikipedia, 14 April 2017.
Ligand-gated ion channel，Wikipedia, 2 July 2017.
Nicotinic acetylcholine receptor，Wikipedia, 20 June 2017.
Nicotinic agonist，Wikipedia, 7 April 2017.
Neurotransmitter，Wikipedia, 28 June 2017.

○ Related articles

[021] 活動電位　action potential
[028] 静止膜電位 resting membrane potential
[044] 伸張反射 stretch reflex

○ Referenced books



[051] Heartbeat pumping 2 (GB#103A02) Tue, 19 Jul 2016 01:33:54 +0000 (heartbeat pumping)
●Invention of heart valve

The structure of the heart is as good as I thought what kind of genius thought it was. We are also impressed with clever piping, but it is particularly amazing to devise a way to pump blood with a simple mechanism. Before human beings invented hand pumps, they are putting practical use of valves completely (laugh).

●Building a heart pump

There is an impression that the heart seen in the textbook has a rather complicated structure. But it combines two separate pumps of venous blood pump and arterial blood flow pump into one with appearance and movement, so either one can explain the basic mechanism of the workings of the heart . Simplifying, the basic configuration including the blood vessels before and after the heart, along the direction of blood flow,

It is arranged in the order of vein (blood vessel), atrium (heart), ventricle (heart), artery (blood vessel).

Although it is a single organ, each area has characteristics in its material and work.心筋線維(myocardial fibers)It is the atrium and the ventricle that make up the heart that repeat contraction and relaxation spontaneously.　Since the heart is made up of striated muscles, it is good at repetition of quick and powerful contraction and relaxation.
On the other hand, veins and arteries, which are blood vessels, are made up of smooth muscles, which can not be quickly moved, but is suitable for maintaining sustained tension.

The central part that works as a pump is a ventricle, and the point is that there are “valves” which are doors that open only to one side at the entrance and exit.

　　Entrance door: atrioventricular valve, valve between atrium and ventricle
　　　　　　　　　　It opens only from the atrium to the ventricle.
　　Exit door: arterial valve, valve between ventricle and artery
　　　　　　　　　　It opens only from the ventricle to the artery.

●Troublesome because it has a name on the right and left

In English, the valves of the left and right arteries are called by their own unique names, and it seems that there is not much to mention the two together.
　　The right atrioventricular valve is a tricuspid valve.
　　The left atrioventricular valve is a mitral valve.
　　The right arterial valve is pulmonary valve.
　　The left arterial valve is the aortic valve.

Each blood vessel connected to the heart also has its own unique name.
　　The veins on the right are upper and lower big veins, vena cava.
　　The left vein is pulmonary vein.
　　The right artery is the pulmonary artery.
　　The left artery is the aorta.

As you can see, it seems like the components are confusing to beginners, as the parts are so many that they are named individually.

●Right and left have different flowing blood

血液循環(circulation)The contents of the flowing blood are different between the right pump and the left pump. The venous blood flowing through the right heart is the blood before it is supplemented with oxygen in the lung after it has traveled through the body. Arterial blood flowing through the heart on the left is fresh blood to be pumped into the body after replenishing oxygen in the lungs. It is a different route which does not mix with each other in the heart.

A pump through which arterial blood flows,
Pulmonary vein ⇒ left atrium ⇒ left ventricle ⇒ aorta

The pump through which venous blood flows,
Caval vein ⇒ right atrium ⇒ right ventricle ⇒ pulmonary artery

In other words, it is independent as a pump. Another difference is that the pressure for sending blood is very different between right and left. The left ventricle to be delivered to the aorta can reach as high as 120 mmHg to 130 mmHg, but the right ventricle that only sends blood to the lungs is enough for that one fifth. However, the two pumps repeat contraction and relaxation pulsation / beat at the same timing. So for now, do not distinguish right and left, think about the basic movement of the heart.

●Do not open the inlet and outlet valves at the same time

Since the movement of the heart itself is also a circulation type, it may start from anywhere, but usually it seems to start with “cardiac cycle” where the atrioventricular valve opens and sucks blood into the ventricle.
1) filling phase
　　　　　　　　Only the atrioventricular valve is opened, and the ventricle inhales blood from the atrium.
　　2) atrial contraction
　　　　　　　　The atrium pushes the blood into the ventricle only a little.
　　3) isovolumetric contraction
　　　　　　　　All the heart valves are closed and the pressure in the chamber increases.
　　4) ejection phase
　　　　　　　　Only the arterial valve is opened, and blood is sent to the artery.
　　5) isovolumetric relaxation
　　　　　　　　All the heart valves close but the pressure in the ventricle goes down.

After that, only the atrioventricular valve was opened and returned to the initial filling phase, after that the same cycle was repeated about 70 times per minute (time of one beat was about 900 milliseconds), making it quiet all day If you do, repeat 100,000 times. Meanwhile, the atrioventricular valve and the arterial valve never open simultaneously.

●The valve opens and closes due to contraction and relaxation of the ventricle

filling phaseIn the “filling period” when the atrioventricular valve opens, the pressure in the ventricle will instantaneously drop to around zero, and it seems to be in a form that draws blood from the atrium.　atrial contracitonAfter that the atrium muscle contracts, followed by “atrial systole” which forces the blood a little bit into the ventricle. In the electrocardiogram, the P wave at the beginning of the cycle overlaps the onset of atrial contraction, so there is a way of explaining this as the beginning of the cardiac cycle. While the blood flows from the atrium to the ventricle, the arterial valve remains closed all the time. Since the opening and closing of the valve and the flow of the blood are not different between the filling period and the atrial systole, there are cases where this is sometimes completed as a filling period collectively without distinction.

isovolumetric contractionThe QRS wave of the electrocardiogram (QRS complex) occurs immediately after the atrial systole, and the pressure rises as the ventricle begins to shrink suddenly, so the atrioventricular valve closes. This is the beginning of the “isovolumic systole”. The vibration that the atrioventricular valves hit each other at this time is the sound of the heart called the first heart sound.
Even when the atrioventricular valve is closed, the exit arterial valve does not open yet, so the ventricle is sealed. When the blood pressure on the artery side is 80 mmHg when it is an aorta (about one fifth if it is on the pulmonary artery side), the inside of the heart chamber just breathed still has a low pressure.　isovolumetric contractionThe arterial valve does not open until the ventricular muscle further constricts and the pressure in the ventricle overcomes the arterial blood pressure. During this short sealed state, the ventricular muscle contracts strongly while the ventricular blood does not enter and exit, and the volume does not change. It is an event of only 30 milliseconds in time.

ejection phaseWhen the arterial valve opens, it becomes the “ejection period”, and the blood whose pressure has increased in the ventricle is expelled to the artery. As the contraction of the ventricular muscle becomes stronger, it pushes the blood into the strained artery as much as possible. Arterial blood pressure peaks beyond 120 mmHg in the left ventricle, then falls slowly as the blood of the artery is pushed out into the blood vessel ahead. On the other hand, the ventricular contraction force falls faster than the arterial pressure drop, and when the pressure reverses, the exit arterial valve closes at once and the ejection phase ends. At this time, the vibration that the arterial valves collide with each other is the second heart sound. (The whole will proceed with the right ventricle under the pressure of one fifth on the left.)

isovolumetric relaxationWhen the arterial valve is closed, the atrioventricular valve remains closed, so that the ventricle is sealed again. This closed state is a phase in which the ventricular muscle relaxes, so it is called “isovolumic diastole”. The atrioventricular valve does not open until the contractile force of the ventricular muscle decreases sharply and the ventricular pressure falls below the atrium.　isovolumetric relaxationThe isovolumic diastolic phase takes about twice as long as the isovolumic systole. Still it will be a momentary incident. When the atrioventricular valve opens, it returns to “filling period” again.

●Blood does not flow in myocardium during ejection period

From the isovolumic systole to the ejection phase, the myocardium contracts strongly.　Blood vessels running in the myocardium are crushed by contraction of the myocardium, during which time the blood is swept out and does not flow into myocardium.　heartbeatInstead, it is a mechanism that allows the heart muscle to relax by the blood pressure of the artery, from the isovolumic diastole to the point before the next isovolumic systole. Blood flowing while the myocardium is relaxing inflates the collapsed blood vessel. This phenomenon seems to be whether the shrieked ventricle regains the shape of the bag and plays a role in aspirating the blood from the atrium, so that when the air is again injected into the air doll where the air has gone out, I think, but how about you?

●Blood flowing in one heart beat

The blood volume in the ventricle is maximized just before the isovolumic systole, and about 120 ml is collected when it is at rest. It becomes the minimum immediately before the isovolumic diastolic phase through the ejection period, but it does not become empty, about 50 ml remains in the ventricle. Approximately 70 ml of that difference is the amount of blood that is pumped out in one heartbeat. However, the amount of blood flowing through the heart fluctuates slightly every time, and it varies greatly depending on how you move the body. When exercising, the heart rate also rises, but the stroke volume per one also increases.

If you consider it normally, there may be an image that the amount of blood remaining in the ventricle decreases by a small amount when the stroke volume is high, and the remaining blood volume increases when the stroke is small. However, the amount of blood remaining in the ventricle does not change basically regardless of whether the stroke volume increases or decreases. Generally, if you reduce the remaining amount in order to spit out a lot of blood, it will not return to its original capacity even if blood normally flows in the next filling period. Conversely, after decreasing the stroke volume by increasing the remaining amount, the ventricle expands to the extent that blood comes in normally. If the stroke volume is reduced in the same way, the ventricles further expands.

heartbeatheartbeatThe heart has an automatic mechanism that does not cause such inconvenience originally. When the myocardium is stretched long, it tries to return to the base stronger. It is a property called the Starling’s law of the heart. Therefore, when heart inhales much blood, there is a nature that the heart automatically expels a lot. If you inhale more, give out more, less as you inhale, give less. So basically the amount remaining in the ventricle remains unchanged. When the stroke volume increases to the maximum, it becomes about twice as much as at rest. Even if the stroke volume doubled, 50 ml remained originally, so it is 50 + 70 × 2 = 190 ml and the ventricular bulge is increased by up to 60%.

●Both right and left blood flow volume is same

Blood leaving the heart passes through the artery around the destination and takes the veins back and comes back. Blood leaving the left ventricle is arterial blood, goes through the systemic circulation circulating in the body, becomes venous blood and returns to the right atrium. Venous blood comes out of the right ventricle and is pulmonary circulation (pulmonary circulation) which is sent to the lungs and becomes arterial blood and returns to the left atrium. The blood volume of the pulmonary circulation is much less than the blood volume of the systemic circulation and the pressure of the pulmonary circulation is only about one fifth of the systemic circulation, so it may be thought whether there is a difference in stroke volume, The amount of flowing blood is exactly the same for both the right heart and the left heart. If stroke volume is not the same as right and left, circulation will be broken. Since the pressure for sending out blood has a large difference between right and left, the timing of opening and closing the valve seems to be slightly shifted right and left in reality. However, if you are not an expert, there is nothing to worry about.

●Heart stops moving even though myocardium is moving

heartbeatIt is said that the heart stops when you die. Of course the heart is stopped when it dies. But, suddenly, even if “the heart has stopped”, the heart itself is not necessarily dead yet. To work as a pump, at least the ventricles inhale the blood and spit out, that much movement and time to allow the blood to flow. The ventricular streaks must repeatedly contract and relax greatly all at once as explained above.　Unfortunately, even if it shrinks in a convulsive state in a small manner like ventricular fibrillation, the valve does not open and it is only wasteful activity. Even if the heart is moving, if it can not work as a pump, it is the same as the heart is stopped. It is this kind of “moving cardiac arrest” that can be helped by using AED in various facilities, that is, automatic external defibrillator as soon as possible.

○Related articles

[041] 心筋線維 myocardial fiber 041-heartmuscle80.gif
[016] 血液循環　blood circulation
[001] 心臓のポンプ機能　heartbeat pumping
[008] 弁の働き　valve in the thin‐walled vessel
[033] 平滑筋の収縮 smooth muscle contraction

○Referenced books



[050] Cellular respiration (GB#101H01) Mon, 30 May 2016 11:43:31 +0000 cellular respiration

● Cells that absorbed oxygen exhale carbon dioxide

The task of extracting energy from nutrients absorbed in the gastrointestinal tract is responsible for each cell making the body. To turn its work, the cell takes oxygen and exhales carbonic acid gas.

● Response of respiration

The nutrients of general cells, energy sources are mainly glucose and fatty acids. In glucose and fatty acid the structure and properties of the molecule are completely different. However, both are compounds of carbon, oxygen and hydrogen. In the process of decomposing this energy is gradually taken out to another molecule, and finally (although it is not really the end though) the energy is subdivided into many ATP (Adenosine Tri Phosphate).

ATP is said to be also called “intracellular energy currency” because the energy incorporated in ATP can be used in a variety of different applications, basically in a common way in the cell. Nutrients originally made from carbon, oxygen and hydrogen, after all the biologically available energy is extracted, eventually become carbon dioxide and water molecules and finish their functions.

The work of extracting the energy that the nutrient has to the end is carried out by the reaction of citric acid cycle (= TCA cycle) in mitochondria. However, before entering the citric acid cycle, pretreatment according to the material must be carried out. mitochondira
If the material is glucose, it turns into two pyruvic acid by glycolysis reaction outside mitochondria and then enters the citric acid cycle via acetyl-CoA in mitochondria.

In the case of fatty acids, after entering the mitochondria, they undergo a process called beta-oxidation, and then enter the citric acid cycle via acetyl-CoA.
Even if oxygen is not taken as occasion, only glycolysis from glucose proceeds. However, the process in the mitochondria does not operate when oxygen gas does not enter.

It is expressed as, in the case of glucose（C6H12O6),
C6H12O6 + 6H2O + 6O2 → 6CO2 + 12H2O + Energy（686 kcal/mol・glucose）
Or, by rearranging the number of water molecules before and after the reaction,
C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy（686 kcal/mol・glucose）

cellular respiration
When extracting energy only with glycolysis in the absence of oxygen, mitochondria is closed and no carbon dioxide is emitted. Only two ATPs are formed in the cytosol, pyruvic acid is converted to lactic acid, and taking out energy from this molecule is a rest for now.

When oxygen is sufficient and all energy available from one glucose molecule is extracted out, approximately 30 molecules (38 molecules in old textbooks) of ATP are made. The energy released from 1 mole (6.02 × 10 23 molecules) ATP is 7.3 kcal (standard state). If it is 30 mol, the energy is 219 kcal, only one third of 686 kcal. Still it is said that the recovery rate of energy is higher than that of artificial institutions such as gasoline engines, as it extracts energy from organic matter. In the cell, energy that could not be transferred to ATP is also used as heat to maintain body temperature, so there is no waste in energy usage.

● Oxygen and carbon dioxide enter and leave by diffusion

Gases such as oxygen and carbon dioxide pass through by diffusing the cell membrane. It expands from the high concentration side to the low concentration side, from the higher partial pressure side to the lower side. Since oxygen is consumed in the mitochondria one after the other, it moves from the outside of the cell, carbon dioxide moves naturally out of the cell as it occurs from mitochondria one after another.

Glucose, on the other hand, can not diffuse cell membranes arbitrarily. A glucose transporter, which is a dedicated carriage protein buried in the cell membrane, is carried from the higher concentration of glucose to the lower side. When glucose is used more and more in the cell, it will be carried from outside the cell. On the other hand, fatty acids pass through the cell membrane by diffusion.

Energy-transferred ATP is basically used only in the cell, not outside. Special transport protein is prepared for lactic acid, and it seems that entry and exit are regulated as necessary.

● ATP per cell (calculation redo)

There is always about 109 (1 billion) molecules of ATP in each cell, and in many cells all ATPs are consumed and replaced every 1-2 minutes” (Essential Cell biology, 2010).
The minimum amount of energy (basal metabolic rate, BMR) consumed by humans only in one day is about 1500 kcal for adults weighing 60 kg.

It will be good if you live normally, it will be about 2,300 kcal. Since 30 moles of ATP is made from 686 kcal of energy of 1 mol of glucose, it is estimated that ATP produced on the human body on a daily basis in this state is 30 × 2300/686 ⇒ 100 mol.
ATP produced (= consumed) per minute is 100 / (60 × 24) ⇒ 100/1440 ⇒ 0.0694 = 6.94 × 10 -2 mol (ATP) /min.

Recent data estimate the total number of cells of adult human with a body weight of 70 kg is 37 trillion (3.7 x 10 13) (it is said that roughly 60 trillion pieces are rough it was …). If it is 60 kg, it becomes 3.7 × 60/70 × 10 13 ⇒ approximately 3.2 × 10 13. By dividing the amount of ATP produced in the whole human body by the number of cells and calculating the ATP consumption per minute of one cell, 0.0694 / 3.2 × 10 -13 ⇒ 0.0217 × 10 -13 ⇒ 2.17 × 10 -15 mol /min/cell.
From now on to the number of molecules, it becomes 2.17 × 10 -15 × 6.02 × 10 23 ⇒ 2.17 × 6.02 × 10 8
· 13.1 × 10 8 molecule (ATP) /min/cell (about 1.3 billion molecules of ATP)
About 10 9 (1 billion) molecules. It is almost within the allowable range, isn’t it?

● Oxygen and carbon dioxide per cell

If this is all glucose as an energy source, 30 molecules of ATP are produced per glucose molecule, so the glucose required for 1 minute is 13.1 / 30 × 10 8 molecule/min.　In fact, fatty acids are more useful as energy sources, but glucose is easier to calculate. Six molecules of oxygen are used to extract all energy from one glucose molecule. Therefore, the number of molecules of oxygen required per minute per cell is 6 times the number of glucose molecules, 6 × 13.1 / 30 × 10 8 molecule ⇒
· 2.61 × 10 8 molecule (O2) /min/cell, (about 260 million molecular oxygen)

In the case of glucose, the amount of carbon dioxide exhaled is the same as consumed oxygen, so the value CO2 / O2 (respiration quotient) is 1.0. When another nutrient or fatty acid is used as an energy source, the proportion of oxygen atoms in the molecule is much smaller than that of glucose, so that on average an oxygen consumption is increased by about 40% compared with the carbon dioxide discharged. Therefore, the breathing quotient is about 0.7. The average breathing quotient of actual breathing of the whole body seems to be about 0.8.

● What about cultured cells?

In cell culture, glucose is often given mainly as an energy source. Then, the oxygen consumed and the discharged carbon dioxide are 1: 1.　In the case of cultured cells of the liver, if 1 x 10 5 cells per sheet 1 cm2 of the cell population grown without voids, 40 pmol (O2) /s/cm2 oxygen is required. Since it is 60 times in one minute, it becomes 2400 pmol /min/cm2.

Calculating from that, the number of oxygen molecules required per minute in this cell population is 2400 pmol = 2400 x 10 -12 mol = 2.4 x 10 -9 mol ⇒ 6.02 × 10 23 × 2.4 × 10 -9 molecule ⇒ 6.02 × 2.4 × 10 14 molecule ⇒ 14.5 × 10 14 molecule ⇒ 1.45 × 10 15 molecule (O2) /min/cm2.　For each cell, 145 × 10 13 / 10 5
・ 145 × 10 8 molecules (O2)/min/cell　(14.5 billion molecular oxygen)
It is roughly 50 times the average oxygen consumption per cell calculated from ATP consumption of the whole body.

In another cell example, there is data that approximately 0.12 pmol of oxygen per hour is required for one cell of myocardial fibroblasts (cardiac fibroblasts). It has less metabolism than the liver. However, since it is a muscle cell, the metabolism will be bigger than the non-moving cell. 0.12 × 10 -12 mol/h ⇒ 120 × 10 -15 mol/h ⇒ 120 / 60 × 10 -15 mol/min ⇒ 6.02 × 10 23 × 2 × 10 -15 molecule (O2)/min⇒
・ 12.04 × 10 8 molecules (O2)/min/cell　(About 1.2 billion molecules of oxygen)
Even this is about 4 times the oxygen consumption calculated from the whole body.

● Red blood cells do not consume oxygen

Actually, out of the whole cell number 3.7 × 10 13 (37 trillion), 2.6 × 10 13, about 70 % is occupied by erythrocyte. From the common sense that the blood as a whole is 8 % of the body’s weight, although it is not convincing at first, it is that the results aggregated with the latest data are so. However, erythrocytes have a diameter of about 8 μm and are small as cells. (As measured by blood test, the number of erythrocytes is a value of about 5 million / μL, so if you calculate from now, 25 liters of erythrocytes will be included in the approximate blood volume of 5 liters per person.)

glycolisisActually, erythrocytes do not have mitochondria, they are fairly specialized cells that procure ATP by glycolysis only. They do not use oxygen nor generate carbon dioxide. They do not use that oxygen despite having a lot. Priority is given to the important work that carries oxygen, although oxygen is full of them, they do not use oxygen themselves. Then in the case of a body weight of 60 kg, only about 10 trillion remaining cells will use oxygen.

Assuming that this number of cells supplements all of the ATP consumed per minute in the whole body as calculated from a metabolic rate of 1 day, the production of ATP per cell is divided by this cell number to 0.0694 × 7 / 6.6 × 10 -13 ⇒ 0.0736 × 10 -13 mol (ATP)/min/cell. The number of oxygen molecules required is 6/30 × 0.0736 × 10 -13 × 6.02 × 10 23 ⇒ 6 × 6.02 × 0.0736 / 30 × 10 10 ⇒ 0.0886 × 10 10
· 8.86 × 10 8 molecule (O2) /min/cell (approximately 900 million molecular oxygen)
Approximately two thirds of the calculated value in cultured myocardial fibroblasts approached.

If there is no mistake in the above calculations, it seems that cultured cells are relatively expensive in oxygen consumption, but there are many cells with less oxygen consumption in the body. If it repeats, but there are no mistakes in calculation and way of thinking, please (check with yourself).
Oxygen consumption in one minute per cell calculated from the total metabolic rate for one day and the number of oxygen respiring cells 8.86 × 10 8 molecule (O2) /min/cell to consumption per second
0.147 × 10 8 molecule (O2) /s/cell (approximately 15 million molecular oxygen).
And, on the other hand, the cells discharge on average about 80% of the carbon dioxide of oxygen.

● Oxygen overflows from capillaries

Oxygen molecules are dissolved in 100 ml of water as a gas at 0.003 ml (3 × 10 -3 ml) per 1 mmHg of oxygen partial pressure. If it is 1 ml (1 cm3) of water, 0.00003 ml (3 × 10 -5 ml) is dissolved.　In arterial blood, oxygen partial pressure is close to 100 mmHg, so 0.003 ml is dissolved per 1 ml of plasma. However, thanks to hemoglobin in the erythrocytes, the blood contains 0.204 ml of oxygen that is nearly 70 times its oxygen.　When this comes to the peripheral capillary, the oxygen partial pressure falls to less than 40 mmHg at a stroke. Considering from the oxygen dissociation curve, at least about 30% of the oxygen contained in the hemoglobin is fully bursting out.

About 1 ml of blood, it is about 0.06 ml of oxygen molecules. However, only around 3 × 40 × 10 -5 ⇒ 1.2 × 10 -4 ml of oxygen per ml is dissolved in the surrounding tissue fluid. That is, it dissolves only the concentration of 0.2 % of the density in the blood. In skeletal muscle cells, oxygen may be absorbed by intracellular myoglobin. However, if it is already full of oxygen, of course, overflowing oxygen will be pushed thinly into the surrounding tissue.

If the cells in the middle do not consume oxygen and the oxygen partial pressure is still 40 mmHg, the oxygen overflowing from 1 ml of capillary blood will simply be calculated as 0.06 / 1.2 × 10 4 ⇒ 6 / 1.2 × 10 2 ⇒ 500 cm3. If the capacity of a cylindrical capillary is 1 ml, it is an image that covers a radius range of about 12 times its diameter. When the oxygen partial pressure is 1 mmHg, spread to the organization of 0.06 / 3 × 10 5 ⇒ 6000/3 ⇒ 2000 cm3. It corresponds to about 23 times the diameter of the diameter.

Since the diameter of the actual capillary is about 10 μm or less, it is about 200 μm in radius. Of course oxygen is consumed by surrounding cells, so the oxygen partial pressure drops sharply as it leaves the blood vessel, and the oxygen solubility decreases accordingly. Actually, it seems that cells are said to be within 200 μm radius around the capillary. It is surprising that there is not much difference in such a cumbersome calculation.

● How much surplus oxygen can afford

1 mol of gas is composed of 6.02 × 10 23 molecule and has a volume of 22.4 L (standard state). When the oxygen partial pressure is 1 mmHg, the oxygen molecules in the aqueous solution 1 cm3 are 3 × 10 -8 / 22.4 ⇒ 3 / 22.4 × 10 -8 mol (O2) / cm3.　The number of molecules is 6.02 × 10 23 × 3 / 22.4 × 10 -8 molecule /cm3 ⇒ 6.02 × 3 / 22.4 × 10 15 molecule /cm3 ⇒ 18.06 / 22.4 × 10 15 molecule ⇒ 8.1 × 10 14 molecule (O2) /cm3.

On the other hand, the average oxygen consumption rate calculated from whole body cells is 0.147 × 10 8 molecule (O2) /s/cell (15 million molecules Of oxygen). Consider how much cells exist in the tissue mass 1 cm3. The number of 1 x 10 5 cells per 1 cm2 of the cultured cell sheet is simply diverted to a cube assuming each cell is a cube. Then, the number of cells is (√ (1 × 10 5)) 3 ⇒ 316 × 10 5 ⇒ 3.16 × 10 7 cell / cm3 (32 million cells). For this mass of tissue 1 cm3, the oxygen consumption per second is calculated as 4.64 × 10 14 molecule (O2) /s/cm3.

As a result, oxygen molecules that can dissolve in 1 ml of an aqueous solution with an oxygen partial pressure of 1 mmHg divided by the oxygen consumption rate of this tissue 1 cm3 yields 8.1 × 10 14 / 4.64 x 10 14 ⇒ 8.1 / 4.64 ⇒ It is consumed in 1.74 seconds.
cellular respirationIf this rough calculation is correct, if it thinks that it will disappear in a moment, 1 mmHg seems to have plenty of room. However, since oxygen released in the periphery should be in equilibrium where it is completely consumed in an instant, it may be that the lower oxygen partial pressure range is covered. Furthermore, if it is a cell that is metabolically active like the liver (because it consumes 16 times in this case), it can be guessed that the distance between the capillary and the cell must be much closer.

● Carbon dioxide gas that is discharged is also carried by the blood vessel

When the cell consumes oxygen, it will exhale it at least as much as 70% of its carbon dioxide. This is an empty shell after extracting all the energy that can be used biologically from the energy source sugar and fatty acid.It is also the final product of the citric acid cycle, and if this carbon dioxide gas is not tidied up, the citric acid cycle will not rotate normally even if there is oxygen. Even without worrying, carbon dioxide spreads from the cell to the capillary, contrary to oxygen, is absorbed by the blood flow returning to the heart and is recovered from the tissue. It is carried to the lungs by blood flow, and it is discharged from the mouth and nose. The respiratory movement of the lungs collectively exchanges the oxygen and carbon dioxide of cells in the body.

However, there is a condition that the concentration of carbon dioxide gas outside the body is sufficiently low to carry out carbon dioxide from the cell to the outside of the body. Carbon dioxide in breath exhaling normally is about 3 to 4 %, whereas the concentration of carbon dioxide in normal atmosphere is 0.03 % and roughly 100 times, so you can breathe in peace. Conversely, if the concentration of carbon dioxide in the inhaled air becomes 3 % or more, it will be impossible to expel carbon dioxide gas out of the body, so it is natural that there are times when the condition goes bad and it leads to death.

Although the unit is confusing, we estimated the gas exchange around the cell in a way that can be calculated even by junior high school students. Professionally, experts calculate using a frighteningly difficult function, but it is surprisingly deep and it can not be said that the clarity has not been clarified yet.

○ Referenced sites

Adenosine triphosphate, Wikipedia, 28 June 2017
・On the number of human cells
An estimation of the number of cells in the human body, Annals of Human Biology, Bianconi et al., Annals of Human Biology
Volume 40, 2013.

・Oxygen consumption of cultured cells
Improvement of oxygen supply in hepatocyte culture, Yuki Sakai, Hepatocyte research group
Oxygen consumption of the human heart cells in monolayer culture, Sekine, et al.(2014), (PubMed)
Lack of Oxygen and Beyond(2009),
Theoretical models of microvascular oxygen transport to tissue, Goldman(2008), (PubMed).

○ Related articles

[011] Body acid-base reaction and carbon dioxide gas
[023] Erythrocyte and hemoglobin
[016] Blood circulation
[029] Oxyhemoglobin dissociation curve
[010] Alveolar ventilation and dead space
[017] Absorption of carbohydratel
[047] Glycolysis
[042] TCA cycle
[019] Adenosine triphosphate
[046] Digestion and metabolism
[013] Lipid bilayer of the cell membrane
[007] Glucose and the hydrolysis of sucrose　
[026] Interaction of myosin and actin
[015] Costal breathing
[038] Homeostasis of the core body temperature 041-heartmuscle80.gif

○ Referenced books


rev.20160604，rev.20160619，rev.20161228，rev.20170506, rev.20170521, rev.20170709, rev.20180106, rev.20180109, rev.20180111.

[049] A neural circuit for voluntary movement (GB#114D08) Wed, 23 Dec 2015 13:49:43 +0000 a neural circuit of voluntary movement
● A comprehensive project involving brains, muscles and senses

In order to manipulate our body at will, a large amount of signals circulate around the brains. The command sent to the muscles is the result signal. In addition, unless confirmation of the effect of the executed motion and correction of the signal are made, it is not close to the movement as desired. The execution of voluntary movements is a big comprehensive project that also incorporates afferent signals from the periphery.

Organization of voluntary movement project

Movement of the face and limbs made by our own intention is voluntary movement. Sometimes there are casual movements that are not conscious of ourself, but regardless of whether we are aware or not, the basic mechanism of execution is the same.
At least the following elements are involved in voluntary movement projects. (Abbreviations are effective only in this site. In addition, because the connection status of information is given priority in this chart, placement does not match the anatomical positional relation in some places. The relationship between the right and the left is also neglected here.)

Cxm: Cerebral Cortex (motor area).
Cxs: Cerebral Cortex (sensory area).
BG: Basal Ganglia.
Thm: Thalamus (motor nuculei).
Ths: Thalamus (sensory nuculei).
Cb: Cerebellum.
Bs: Brain Stem, Brainstem / Sc: Spinal Cord.
Ms: Skeletal Muscle.
S: Sensory organ.

* As a neural circuit for voluntary movement, the boundary between the brain stem and the spinal cord is not so clear in fact. Especially in the medulla, although there is a difference in the level of function, it seems to be an extension of the spinal cord. Also, the action of medulla oblongata and pons seems not to be clearly distinct as that form. So, here we are batching the brainstem and the spinal cord on purpose to make the story as simple as possible.

● Two loops of basal ganglia and cerebellum

A terribly rough explanation (you can only do a rough explanation on this site), in the brains that are in the skull (cranium), two large loops are spinning around for a voluntary movement.

【Loop of basal ganglia】
basal ganglia loop· Cerebral cortex (Cxm) in the motor system ⇒ basal ganglia (BG) ⇒ thalamus in the motor system (Thm) ⇒ A loop returning again to the cortex of the motor system.
This loop organizes the goals and projects of movement according to the motive of movement and narrows down the optimal movement from various repertoires of movement.

【Cerebellar loop】
cerebellum cortex loop· Cerebral cortex of the motor system ⇒ Brain stem (Bs) ⇒ Cerebellum (Cb) ⇒ A thalamus of the motor system ⇒ A loop returning again to the cortex of the motor system.
While executing movement, correct errors of motor commands to muscles and preserve optimal correction pattern.

※ The thalamus (Th) looks like a united chunk of left and right respectively. But, for example, in terms of logistics, it is like a big wholesale district where large sections of goods are handed over at different times, with divisions divided by department. The thalamus of the motor system (Thm) and the thalamus of the sensory system (Ths) are separated, and basically the signal of the basal ganglia and the signal of the cerebellum flow in separate sections, even in the thalamus of the motor system.

● Two flows to perform movement

The cerebral cortex (Cxm) creates a motor program based on the information of the cerebral basal ganglia loop and decomposes it into contraction and relaxation motor command signals for each muscle or group of a few muscles and reorganizes it. It transmits its decomposed / rearranged signal to the brainstem (Bs) and the spinal cord (Sc) through the efferent’s descending tract. Motor neurons in the brain stem and spinal cord exert peripheral nerves called cranial nerves and spinal nerves and execute the activities of the respective muscles according to the signals. Neurons not going out of the brain or spinal cord are sometimes called roughly “motor neurons” that relay the motor system. Therefore, in order to clarify the position, neurons that directly move the muscles by peripheral nerve fibers are also called “lower” motor neurons. There are two major routes on the descending path from the cortex to the spinal cord.

【Pyramidal tract】
This is a descending route that carries a signal of motor command without interruption until the neural fibers of cerebral cortex neurons reach the brainstem or spinal cord lower motor neuron. Routes that extend to the spinal cord are called corticospinal tract by arranging the departure place and destination in an anatomical practice, but since most go through the pyramidal decussation of medulla oblongata, it is also called pyramidal tract.

Since the brainstem is above pyramidal decussation, the fibers reaching the lower motor neurons such as the facial nerve in the brainstem from the cerebral cortex do not go through pyramidal decussation. However, as a relationship to the lower motor neuron, it seems to be the same as the corticospinal tract, so this is also often treated as “pyramidal tract” functionally as a whole. We do not distinguish it even in this chart. When it is necessary to distinguish it from the corticospinal tract, say cortinuclear tract. In this case, “nuclear” refers to a mass of lower motor neurons in the brain stem, such as a facial nucleus. The corticobulbar tract is one of the cortical nuclear tracts relaying in the medulla oblongata, but it is also used as a synonym for the cortical nuclear tract.

neuro-motorsystemThe region of the cerebral cortex that exits the pyramidal tract forms a special area called the “primary motor area”.

[Extrapyramidal tract]
Extrapyramidal tract represents the meaning of “not a pyramidal tract” among descending motor paths of the spinal cord. Certainly the pyramidal decussation is out. But it does not matter that it does not go through pyramidal decussation, the important thing is that there is a relay point in the brainstem. In other words, after the signal exits the cerebral cortex, it changes the neuron via the synapse at least once in the brain stem, and the nerve fiber that originates from the brain stem reaches the lower motor neuron.

Specifically, these routes include cortex ⇒ red nucleus ⇒ spinal cord route with the nucleus ruber of the midbrain as a relay point, or a reticular formation spreading from the top to the bottom in the brainstem, cortex ⇒ reticular formation ⇒ spinal cord route, or cortex ⇒ reticular formation ⇒ medullary motor nucleus root.

The fact that there is a relay point means that before the lower motor neuron is reached, signals are divided to other places, mixed with signals from others, a bit of reworking of signals of movement comes in. Nerve fibers running from the cerebral cortex to each relay point, including the primary motor cortex, come from a wider range of cortical areas. Anatomically, as “extrapyramidal tract” in which fibers are bundled, it refers to the red nucleus spinal cord tract leading from the relay point of the brain stem to the spinal cord and the reticulate spinal cord tract.

In summary, the motor command that reaches each lower motor neuron from the cerebrum is carried in the direct route (pyramidal tract) from the cerebral cortex and the indirect route (extrapyramidal tract) relayed by the brain stem. For the direct route, the motor command considered by the cerebral cortex is transmitted as it is, and the indirect route gives a slightly revised motor command in the brain stem. A signal that captures and coordinates both commands and in situ information from the muscles and tendons via the spinal reflex circuitry around the lower motor neuron causes actual skeletal muscle movement through the lower motor neuron.

● Check actual movement

There is no guarantee as to whether or not it is the movement you want, even if you put effort into the muscle according to the motor command. Therefore, the motor system mobilizes various sensory functions all at once and checks the results of the movement instantaneously. The most fundamental thing is information on states such as muscles, tendons and joints, called the deep sense (proprioception). Familiar muscle spindles and tendon organs and the like instantly fine-tune the activity of lower motor neurons with spinal reflex while raising information to the brain one by one through ascending conduction pathways.

Where to go in the brain, the important destination in motor control is the cerebellum (Cb). To the cerebellum, a copy of the motor command going from the cerebral cortex to the lower motor neuron is input via the brainstem with another route. It is said that in the cerebellum, cortical motor command and actual body movements are checked. The greater the error range of the result, the stronger signal is returned to the cerebral cortex making the motor program through the thalamus. The cerebral cortex corrects the motor program according to the signal from the cerebellum, and transmits the motor command again.

Every time this loop is turned during an action, the error becomes small and it approaches the target of movement. With instantaneous movement, this correction will not make it in time. Even if it does not work in a single operation, the repetition of the operation many times will reduce the range of correction. By repeatedly executing various motor programs, each modification pattern seems to accumulate. This error correction loop is also a circuit of motor learning at the same time.cerebellum cortex loop

Frequently cited in motor learning is driving a bicycle. There will not be so many people who can ride a bicycle for the first time and run soon. Perhaps everyone will be able to run very well at first. However, with repeated excercises, almost anyone will be stable. Once you can get on, it is normal that even if you have not been riding a bicycle after that, even if you have forgotten to ride, it will not take long to get on again. The invention of a bicycle is the last thing in human history, and although the “bicycle riding program” is not prepared in the human brain in advance, the pattern of the motor program acquired by practicing is properly It means that it is memorized. Even if you forget the knowledge of the textbook you studied at junior high school, even if you forget it, the memory of the motor program thus acquired lasts for a long while without using it. This is an important point for living by using the body well while pulling out accumulated movement patterns according to various situations. It goes without saying, however, that special efforts are required to maintain the best performance just like the athletes.

Since the important checkpoint of motor learning is the cerebellum, when the cerebellum is affected by the lesion, the data of the motor program accumulated so far can not be used. It is essentially the same as having the data disappeared. So you have to recreate the motor program a bit, but the checking function does not work so you can not fix it. When the cerebellum is affected, although it can roughly move the skeletal muscle, it becomes a motor dysfunction “ataxia,” which is not effective in regulating force or direction. On the contrary, the work of the cerebellar loop is explained from the study of such a disorder.

● Confirm actual feel

sensory-feedbackBesides motor equipment such as muscles and tendons, it is also important to check the results of movement by touching it with your eyes. Even if you hit the keyboard, the computer that the monitor disappeared would not be very useful even if it is moving. Even if you grab things, what will happen if you do not touch it? Let’s grab a rubber ball with a magic hand by remote control while looking at the screen of the personal computer. Even if it can be seen on the monitor, if the magic hand does not convey the feeling of touching the object, if you only operate slowly while watching the situation, you will skip the ball rather than grabbing it.
The stimulation of the skin generated by the actual movement is instantly sent to the cerebral cortex through the thalamus (Ths) of the sensory system. Therefore, it seems to work on confirming the motor program by exchanging information with the motor cortex as well as causing a sense of touch sensation in the sensory cortex (Cxs).

In a video game or the like, players “fight” with ultra-fast movement even without touch. However, it does not know how to be conscious, but it is established because it divides it into another world that was totally outraged. A mechanism that smoothly executes ordinary realistic voluntary movements is a system integrated with feedback (feedback) of information about various situations caused by exercise.

● Choose an movement that fits your intention

In the first place, you do not know where the motivation to do some movements, for example to ride a bicycle, or to take a certain posture comes from. However, if motivation is decided, it is not easy to say that the motor program will be decided. Even with an intentional movement, there is no single actual procedure. Every day in various situations, a new motor learning has been done, and a repertory of motor programs has accumulated in myriads. However, because there is only one body, only one of them can be executed at a time. For example, you go from your home to a friend ‘s house, there are various directions, and it is completely free to pick which one you choose, there is only one way to walk at a certain point.

Thinking about the weather at that time and other things to do, you will choose the way.　basal ganglia cortex loopRoughly speaking, it can be said that it is the loop that goes around the basal ganglia (GB) that judges the situation according to the intention and purpose of the motive and narrows down the program to be executed as it is concerning movement .

The reason is that the typical symptoms when the basal ganglia is affected by the lesion is that involuntary movement, in which a coherent movement does not stop arbitrarily and stops.　From the name it seems like an “unsuccessful” movement but in fact the “uncontrollable” movement is closer. There are also some variations in involuntary movements, but it seems like a form of fighting trying to do some movement at the same time, regardless of intention, failing to narrow down the movement anyway. The output from the basal ganglia to the thalamus mainly works on inhibition. Involuntary movements can be thought of as causing weak activation of the cerebral cortex by suppressing this suppression to a level weaker than usual and not suppressing thalamic activity.

Meanwhile, there is a famous disease, Parkinson’s disease. This is also known as the disease of the basal ganglia, but this is characterized by the fact that the body solidifies and the movement is extremely small. At this time, suppression from the basal ganglia is too strong, suppressing thalamic activity. Therefore, cerebral cortex activity is also weak, it is thought that you can not choose motor program. With this disorder, if there is a specific instruction to the goal of movement, you can begin exercising relatively easily. This is why you proceed anyway if you choose to choose one of the paths to your friend’s house, but it seems that you alone are not resolved without being decided. The “resting tremor” that the fingertips will continue to move freely while still at rest is like a pieceita of hardship.

Basal ganglia was attracted attention due to obstruction of the motor function whose symptoms are easy to see. However, the basal ganglia as a whole has a signal loop that spans the entire frontal lobe. For that reason, it is thought that functions that do not appear as movement, such as thought functions, work similarly to movement.

● “Extrapyramidal disorder” is a disorder of the extrapyramidal pathway?

Movement disorders such as involuntary movements and restless tremor that appear in disorders of the basal ganglia were formerly called “extrapyramidal symptoms”. Even now, it may be understood by medical practice, but it is not used in national examination.In the era when the knowledge of neuroanatomy was incomplete, the mechanism of motor control was supposed to be “easy to understand” schema called a bimodal conception of the extrapyramidal system controlled by the basal ganglia via extrapyramidal pathway, in parallel with the cerebral cortex ⇒ cone pathway system of the pyramidal tract. Extrapyramidal symptoms are a remnant of that age.

The reason why this term is no longer used is that subsequent studies have shown that extrapyramidal tracts are also predominantly dominated by the cerebral cortex. In other words, it has been found that there are only a limited number of routes directly going from the basal ganglia to the extrapyramidal route, such as a part related to the mind unconscious walking pattern. In the end, it means that the actual condition of the “basal ganglia – extrapyramidal system” which had been supposed before has become disappointing. Although the anatomical “extrapyramidal tract” still exists, it is difficult to explain many “extrapyramidal symptoms” by the extrapyramidal lesions.

However, in textbooks that are not professional, these information are not fed back easily. “Extrapyramidal system” and “extrapyramidal symptoms” are still alive and confusion of terms and concepts will continue for a while in Japan.

○ Referenced sites

Motor control, Wikipedia(2017)
Motor coodination, Wikipedia(2017)
Degree of freedom, Wikipedia(2017)
マイナビニュース, 行動を決めるのには大脳基底核と前頭葉連合野が連携が重要 – 東京都医学研(2013年8月)
筧慎治(2001), 大脳小脳連関：小脳は大脳にどんな貢献をしているか －運動制御の観点から.
小脳の学習と内部モデル (眼球運動を題材 に) ，川人光男， J-STAGE Journals- 日本神経回路学会，2001.
高草木薫(2009), 大脳基底核による運動の制御.
平井宏明ほか(2012), 筋拮抗比の概念に基づくヒト歩行動作の運動要素分解.
不随意運動, Wikipedia(2017)

○ Related articles

[044] 伸張反射 stretch reflex
[054] 気道と食道の切り替え switching of the airway and esophagus (GB#105A04)
[021] 活動電位　action potential
[031] 興奮伝導 conduction of excitation

○ Referenced books


rev.20151224, 20151225, rev.20160725，rev.20170709,rev.20170714, rev.20171222, rev.20171224, rev.20171229.

[048] Epidermal cell turnover (GB#117A02) Tue, 07 Jul 2015 12:19:08 +0000 epidermal cell turnover
● Forefront to protect the body

It is said that 60% of the body is water. Though it is full of water in the body, it does not leak out of the skin thanks to a very thin epidermis that covers the outermost side of the skin. The epidermis also protects the cells inside from infiltration of water and various substances from outside, mechanical friction and ultraviolet attack. Furthermore, infiltration of bacteria is also watched here. The wonderful nature of the epidermis is that while cells are exposed to various attacks, the cells change little by little every day and are always fresh.

● Epidermis swapped in 4 weeks

Skin refers to the epidermis of the part touched from the outside and the dermis underneath. Since the thickness of the epidermis is about 0.2 mm, it is only about one sheet of New Year’s postcard. About 20 to 30 layers of cell layers are packed in it. Histologically, it is a form of stratified squamous epithelium.The deepest layer is in close contact with the rough structure called the dermal papilla below it via a sheet called a single basement membrane.Except for a few special ones, all the cells that make up the epidermis are keratinocytes born of the cell division of basal cells stuck just above the basement membrane. epidermal cell turnover basal-cellWhile keratinocytes are pushed up sequentially from bottom to top, they change shape and properties between them. Later in the latter half of life activity is over, it turns into a sheet of thin thin piece called corneocyte made of epidermis-specific substance. And about 28 days after birth (there are some materials around 45 days ← this one seems to be new), peeling off from the outermost side. Every day in the whole body, roughly several grams of keratin is stripping. So even if a small prickle sticks, if the majority are above the basal cells, it will be lifted along with the cells and will naturally escape.

● Cells change greatly in their lifetime

The keratinocytes divided from the basal cells will no longer divide.As the cell is in an inflated form about 2 weeks in the first half while being pushed up little by little every day, because special connection between surrounding keratinocytes looks like a small thorn, it is called the spinous layer It is contained in the layer.After that, the keratinocytes become suddenly flattened, and granules made of a material called keratohyalin become conspicuous in the cells, so that it reaches a short stage of 2 to 3 layers called a granular layer.　epidermal cell turnover granular-layer

Later, the cell nucleus is lost soon, the whole cell almost becomes a sheet of a mass of protein called keratin, and it is peeled off after staying in the stratum corneum for the latter two weeks.epidermal cell turnover hornyJust as human beings were born, aged, and finished their lives by lifetime, there was a site already explained as if it is an image of the world changing appearance and role.

● Keratinize by scattering scattered keratin

Keratin is also famous as the main ingredient of hair and I realize that it is a very durable ingredient. It is also common sense that the horny skin is made of keratin. So, if I thought that the granular layer just before it changes to horny is about to produce the keratin, keratin itself is actually being made as a fiber of the cytoskeleton from among the spinous cell layer. The substance called filaggrin, which is formed by changing the keratohyalin granules made of the granular layer, functions to fix and solidify the keratin proteins scattered inside the cell, so that it becomes a firm and hard structure suddenly.　

● stratum corneum is surprisingly high function

Cells lining horizontally in the granular layer are adhered specifically by tight junction and strongly restrict the passage of various substances from above and below the granular layer. When going up from the granular layer, the other parts and structure inside the cell almost disappears and the cell dies. So the stratum corneum seems to be a mass of keratin sheets that wait for it to peel off later, but it was not that simple.Between the sheet and the sheet, it is filled with a substance called ceramide of cell membrane lipid and binds the sheets, which is also useful for waterproofing. Also, once keratin solidifies, the help of filaggrin seems to be unnecessary, and filaggrin is degraded in the stratum corneum. However, this degradation product now works well as it functions as a moisturizing factor to confine moderate moisture in the stratum corneum. Furthermore, the sebum secreted from the sebaceous glands of the skin covers the entire surface of the stratum corneum. With these elements cooperating, the stratum corneum becomes a powerful barrier to limit the ingress and egress of moisture while maintaining adequate moisture inside.

● No blood flows in the epidermis

Every day the epidermis is born a new cell, the born cells continue to live for at least two weeks to the granule layer, but there are no capillaries around the cells. The tip of the capillary blood vessel folds under the basement membrane at the dermal papilla. For this distance, there is no problem with the gas exchange and mass exchange with the granule cell layer.As far as gas exchange is concerned, direct exchange with the outside world through the stratum corneum may be possible if it is a granular layer, but for humans it may be, but it seems to be the extent that it is not necessary. On the other hand, because there is no blood vessel in the epidermis, it will not bleed even if it gets scratched up to the epidermis. Since there is no bleeding, bacteria and the like are also less likely to enter the blood vessel. Because nerve fibers of pain sense also come only to the dermis, we do not feel direct pain. Since the skin is often damaged, we can see the attitude that it is not treated as serious as it is.

● There are cells that patrol inside the epidermis

epidermal cell turnover Langerhans cellWhat we are surprised to learn about the epidermis is that if you thought like the outer walls that physically and biochemically protect the boundary without skin, blood vessels and nerves, innumerable special cells are always there It means that you are moving freely by watching the invasion of foreign enemies. This is a group of cells that acts as a dendritic cell called a dendritic cell. It has a special name of Langerhans cells, but there is no functional connection except for the fact that the discoverer is the same as the pancreatic islet of Langerhans.As Langerhans cells migrate laterally through the spinous layer, they sometimes stretch branches (dendrites) into granular layers, and it seems that they are checking for extraneous matter there. And when there is a change, it enters special warning posture (activate), it prolongs the protrusion and moves to the side of the granule layer, and swallows it if it is bacteria. Langerhans cells that swallowed foreign matter immediately will escape from the epidermis, merge into the lymphatic system of the dermis, and act to activate immunity activities such as antibody production.

● Langerhans cells come from the root of hair

Langerhans cells are originally a kind of blood leukocytes, which settled within the epidermis. Why is it in the epidermis although there are no blood vessels? After swallowing a foreign body, it can move to the dermis beyond the basement membrane, so it seems that this cell may come in anywhere, but there seems to be a fixed route when entering.The root of the fur protruding from the skin is stuck in the dermis. The circumference of the root is not cells of the dermis but cells surrounding the epidermis surround it. The root of the sweat gland is similarly penetrated deep into the dermis by the tissue of the epidermis.When leukocyte monocytes crawl out of the capillaries in the dermis, they turn into macrophages. Dendritic cells are macrophages that have settled in the dermis, and Langerhans cells are those in which macrophages have entered the epidermis from the root and sweat gland parts.

● Keratinocytes do not turn black when burned on the day

epidermal cell turnover melanocyteThe longer the sunlight hits, the darker the skin. It is well known that black pigment called melanin is increasing to protect the body from ultraviolet rays. It is the keratinocyte of the epidermis that is dark.However, unexpectedly, keratinocytes do not react to ultraviolet rays to produce melanin.On the basement membrane, another cell, called melanocyte, exists in parallel with the basal cell, and this cell takes over in melanin production.Melanocytes do not change to keratinocytes. Upon being stimulated by ultraviolet rays, melanocytes extend the protrusions in all directions and pass the granules packed with melanin to adjacent keratinocytes. That is, melanin granules of keratinocytes are gifts from melanocytes.

● Epidermal cells are not born from the dermis

The epidermis is in close contact with the dermis and papilla via the basement membrane. If there is something damaged and the epidermis peels off and the dermis is exposed, the blood vessels are injured and naturally bleed. When the injury heals, will the epidermis regenerate from its dermis? Since it is a continuous structure, it seems to be okay with that, but in fact it does not happen. Epidermal basal cells and dermal cells are making skin together, but their birth and growth are completely different. Basal cells of the epidermis are epithelial tissue and the dermis is a different organization called connective tissue. More dating back, the epidermis is derived from ectoderm, the dermis is derived from mesoderm, at least in the natural flow, biologically, from the dermis (mesoderm tissue) to the epidermis (ectoderm tissue) (unless you do a special operation ), It is not born.However, even if the epidermis is peeled by appearance, if the cells of the same lineage as the epidermis survive the hair root portion buried in the dermis or the root of the sweat gland, the epidermis spreads out from the cell and is regenerated.Otherwise, we only have to wait until the basal cells gradually spread out and accumulate keratinocytes from the edge of the epidermis that remained without peeling. Small burns are almost restored with this mechanism.

● There is no epidermis in the leather wallet

If I thought that the surface of the leather that used supple and durable animal skin such as bags and shoes made use of the characteristics of this epidermis, unexpectedly, in the beginning of the leather making process, the epidermis is stripped cleanly. Leather is a work of connective tissue, the surface of leather that we touch directly becomes just part of the dermal papilla.Even if you leave the epidermis, it seems that it gets fuzzy, it gets peeled naturally and becomes dirty. In other words, the epidermis makes a strong barrier with dead cells, but if it really dies to the root, it will not be able to fulfill the role of barrier. In other words, it is a proof that the epidermis is alive, that the keratin of the dead cells will act as a barrier.

○ Referenced sites

· New dermatological science 1. Structure and function of skin (Hokkaido University School of Medicine Department of Dermatology)
· Skin tissue photos　⇒　WEB HISTOLOGY(UMIN)
Sensory organ system – hull (skin and its appendages)
・基底層が美肌を　February 19, 2009
・肌細胞の一生を知る　February 14, 2009
· New wound care (Mutsuki Natsui)
· Mystery covered with skin
· Dynamics of skin barrier and Langerhans cells (Ryoji Kubo)
· New significance of hair’s significance – hair follicle immune switch – Keisuke Nagao
· Common sense when applying to dermatology Chikakane Dermatology
· Structure and function of the epidermis (KAO skin care navi)

○ Related articles

[045] Arteriovenous anastomoses in skin
[017] 糖質の吸収　absorption of carbohydratel
[034] 精子形成 spermatogenesis
[030] Endocytosis and intracellular digestion
[013] Lipid bilayer of the cell membrane
[016] 血液循環　blood circulation

○Referenced books


rev.20150709. rev.20150710.　rev.20150813，rev.20161228，rev.20170506，rev.20170709.

[047] Glycolysis (GB#106A02) Sat, 31 Jan 2015 00:22:30 +0000 glycolysis
● Divide glucose into two pieces

Glucose that cells favorite is a mass of energy. Mitochondria transfer the majority of its energy to a number of adenosine triphosphate (ATP) that is easy to use. However, unexpectedly the glucose intact is not good, it does not fit the mitochondrial mouth. First of all, it is necessary to divide the glucose in half by “reaction of glycolysis”.

● Firewood splitting work of cells

glucosepyruvatepyruvateGlucose is representative of human carbohydrates available. Basically, biological membranes themselves do not pass carbohydrates, as it required a special mechanism to take them into cells. Mitochondrial membranes are not as good as those of glucose. Glucose is divided in half to make two small molecules of organic acid called pyruvic acid. If mitochondria is a burning kiln that burns energy, it seems to break firewood into two pieces so that it can enter into the furnace mouth. However, one piece of pyruvic acid prepared by glycolysis is slightly smaller than half of glucose.

● Energy is slightly reduced after splitting

Glucose is a compound with 6 carbon atoms, 1 mole (6.02 x 1023 molecules) has energy of 686 kcal. Whether it turns on fire or burning at once, it decomposes in the cell carefully, but when it finally becomes water and carbon dioxide, it releases this energy as a whole.
On the other hand, pyruvic acid has 3 carbons, 1 mole has energy of 282 kcal. In glycolysis, two molecules of pyruvic acid are produced from one molecule of glucose, but 2 moles of pyruvic acid causes only 564 kcal, twice that of 282 kcal. Deduction of energy of glucose and energy of two molecules of pyruvic acid, where did the 122 kcal go?

● The missing energy has been transferred to other substances

The advantage of glycolysis is that it creates two molecules of ATP at once, quickly, before the reaction of mitochondria. ATPWhen mitochondria generates ATP, it finally needs oxygen molecule 02. But glycolysis does not need that oxygen. Also in the process of making pyruvic acid, ATP is made from adenosine diphosphate (ADP) in advance. Glycolysis is important as a production process of ATP without oxygen. However, the energy change of ADP → ATP is 7.3 kcal (value in the standard state) at 1 mol, and only 2 molecules is 14.6 kcal. In the actual intracellular environment, it will be a little bigger, but it will still be around 20 kcal. NADHMost of the difference energy is transferred to reduced form nicotinamide adenine dinucleotide (NADH), another type of energy carrier. This is energy that can not be transferred to ATP without the help of mitochondria, so it is usually not collected much attention when studying glycolysis, but the energy is being collected properly.

● The reaction of glycolysis is a bit confusing

In short, glycolysis is a chemical reaction that transforms glucose into two pyruvic acids. In the process, this reaction produces two molecules of ATP and two molecules of NADH. That’s enough for beginner level physiology.

However, in medium textbooks, two molecules of ATP are used in the glycolysis reaction, and four molecules are made, so it is written that two molecules of ATP are deducted. In order to understand this it is necessary to look into the contents of the process a little more. The process is unexpectedly complicated, consisting of 10 steps of process, aligning with the TCA cycle which is apparently complicated and inaccessible. Roughly speaking, 5 stages in the first half are reactions that involve energy, and 5 stages later are responses to extract energy.

Every time, since exchange of each element of the reaction and exchange of energy are done by interaction with the enzyme, chemical reaction can not be accurately represented only by the compound as the substrate. With this, it is only necessary to grasp the approximate image.

● Do not let glucose escape

First of all, glucose entering the cell by the glucose transporter dedicated to cell membrane glucose remains out using the glucose carrier again if left as it is. Therefore, the enzyme that finds glucose first takes the phosphate group from ATP which is around there and adds it to glucose. X6P-glucoseThen, it is no longer “glucose” but it is transformed into another substance called glucose 6-phosphoric acid (G6P). That is the reaction 1.
“6-Phosphoric acid” does not mean six phosphoric acids, as you can see from the structure. It means that phosphoric acid binds to the 6th carbon of the structure. Since there is no carriage that puts phosphoric acid stuck substances out like glucose-6-phosphate, it can not escape from the cell. And that energy of this phosphate may be thought of as a “spirit” for starting glycolysis reactions from now on.

(If there is sufficient ATP in the cell and there is not much need to replenish ATP by degrading glucose, replace the phosphate group with carbon number 1 in the structure.　Then the glucose is turned towards the process of extending glycogen.)

● Glucose is converted to fructose and phosphate group is added

Next, prepare to add another phosphate group to glucose-6-phosphate. Later on, this process breaks down the compound and creates two identical molecules, so prepare another phosphoric acid beforehand so that it will not run away as soon as it is released.
Prior to that, in order to make the place (–CH2OH) to attach the phosphate group, in reaction 2, the annular structure of glucose is opened and the place of hydrogen is replaced. Elements that make up that do not change, but it has changed to another sugar called fructose. X16P-fluctoseThe compound is named fructose 6-phosphate.
Immediately after that, fructose 1,6-bisphosphate is made by adding phosphate group from new ATP in reaction 3. Bisphosphate means two phosphates.

● Divided into two to become each fuel

In reaction 4 and 5, fructose 1,6-bisphosphoric acid is broken to finally produce two molecules of compound. Although this reaction is quite complicated, there is no entry particularly in terms of energy, so its explanation is omitted.
glyceraldehyde 3-phosphateThe finished 3-carbon sugar glyceraldehyde 3-phosphate is the substance at the end of the preparation period of the first half of glycolysis, and it spends two molecules of ATP per glucose molecule before coming here.
From now on, it’s the process of extracting more energy than this amount spent.

● Transfer the projecting energy to NADH and ATP

NADHFirst, in reaction 6, electrons and hydrogen having energy from glyceraldehyde 3-phosphate are absorbed by a reaction in which nicotinamide adenine dinucleotide (NAD+) becomes NADH. BisphosphoglycerateWith the remaining energy, phosphoric acid that is staggering alone binds to 1,3-bisphosphoglyceric acid.
G3P3In reaction 7, the first ATP is generated by replacing the phosphate bond with its energy immediately with ADP. The remaining part turns into a substance called 3-phosphoglycerate (glycerate 3-phosphate).

● When another ATP is produced, the completion of pyruvic acid

Even though one ATP can be made, one phosphate remains in this 3-carbon compound (glycerate 3-phosphate). This phosphate group is substituted for ADP in reactions 8, 9 and 10 to produce ATP. Reactions 8 and 9 have preprocessing to make ATP, but at this time, it does not matter.　The substance from which the phosphate group has cleared is at last pyruvic acid.　 pyruvateThere is still 282 kcal of energy remaining in pyruvic acid. The majority of the 61 kcal, which is 282 kcal minus the half value of glucose energy, was transferred to NADH and ATP, and a small portion that was not transferred worked as the driving force to advance the whole reaction.

● After spending two ATPs, four are produced

After all, in the first half, before disassembling one molecule of glucose which is a hexose sugar into two, first decompose two molecules of ATP and attach two phosphate groups therefrom to make two identical three monosaccharides . After that, each process extracts a little energy of 3 monosaccharides, each producing 2 molecules of ATP, pyruvic acid is made. Since 2 molecules x 2 = 4 molecules of ATP are recovered later by consuming two molecules of ATP, two molecules of ATP are collected from one molecule of glucose. Also remember that there are two molecules of NADH. It is estimated that this enters mitochondria and produces three molecules of ATP. Of course, at this time pyruvic acid also enters the mitochondria, and the TCA circuit sucks up the energy of the drone, eventually producing approximately 30 molecules of ATP in all.

However, it is only condition that NADH is processed and ATP is born only oxygen breathing can be done. If the cell’s oxygen molecule O2 is insufficient, mitochondria will be closed and only 2 molecules of ATP made directly in the glycolysis can be increased.　lactic acidAt that time, NADH which does not enter mitochondria presses 2H+ against pyruvic acid, converts it to stable lactic acid, and itself becomes NAD+. That’s why lactic acid increases in anoxic breathing.

● Kaito-kei and Kaito

In Japan, it is ambiguous to say “Kaito-kei” or “Kaito” by textbook as a word that describes the process by which glucose to pyruvate, possibly lactate, can be formed. Which is right is that neither is correct, either. There are explanations that so-called nuances are somewhat different, but it also varies, and both “Kaito-kei” and “Kaito” are simply glycolysis in English, so there is no such distinction internationally. In technical terms, -kei is usually equivalent to -system in English, I guess they are using it because it’s a little cool.

○ Referenced sites

解糖系という概念に対する異論, 歴史生物学への誘い, 2014年1月8日.
炭水化物とアルコール, 生活習慣病を予防する食生活, 佐藤章夫.


○ Related articles

[007] ブドウ糖と，ショ糖の加水分解　glucose and the hydrolysis of sucrose　
[017] 糖質の吸収　absorption of carbohydratel
[050] Cellular respiration
[027] ペプチド結合 peptide bond
[032] グリコーゲンの合成 glycogen synthesis
[042] ＴＣＡ回路 TCA cycle
[019] アデノシン三リン酸（ATP) adenosine triphosphate
[026] Interaction of myosin and actin

○ Referenced books

Lehninger Principles of Biochemistry 6th, International Edition, Macmillan Higher Education, England.

rev.20150202，rev.20150315，rev.20160507，rev,20160618, rev.20170211，rev.20170506，rev.20170709.

[046] Digestion and metabolism (GB#105A02) Mon, 08 Dec 2014 11:12:18 +0000 digestion and metabolism
● Digestion outside the body, metabolism in the body

Eaten are broken up into small units by digestion in the gastrointestinal tract and absorbed into the body from the surface of the tube. Beyond the cell membrane of the wall of the gastrointestinal tract will become “inside the body”, but digestion is a work to be done in the “outside world” in the gastrointestinal tract as preparation for absorption. Absorbed nutrients are withdrawn energy by metabolism in the body.

After that, quite roughly, in the form of carbon dioxide gas, water molecules and nitrogen compounds, that is, breath, urine, and sweat, it is thrown out again outside. Where is that poop? The substances making the feces are the leftovers that were not absorbed by the intestines and the debris of the cells that have changed the intestines (in addition, intestinal bacteria and their debris).

● Nutrients are not absorbed unless they are digested

Nutrients are not absorbed in the body as they are. The thing put in from the mouth is the product of another creature.There are lots of things that do not fit your body as it is. After all, even if the compound of the same nutrient is needed in the body, we do not do detailed things like getting in with special route as much. Once all nutrients are broken down into decomposed elements.Absorb with the element parts, reassemble the necessary things in the body again. On the other hand, if the substances that were in the body are swapped to each part in turn, they are further dispersed and energy is extracted and the debris is thrown out of the body. This is a very rough process of digestion, absorption and metabolism.

● 3 types of nutrients to be digested

met-stm.gifAccording to the “Nutrition Labeling Standard” set by the Japanese Ministry of Health, Labor and Welfare, nutrients are protein, lipid, carbohydrate, 13 kinds of inorganic salts and 13 kinds of vitamins. Among them, the first three are called three major nutrients. In order to be absorbed by the body, nutrients need to be decomposed and digested into the constituent unit components.

In other words, proteins are broken down into amino acids that are monomers, lipids are decomposed into glycerin and fatty acids, which are constituent parts, and carbohydrate is decomposed into monomeric monosaccharides. For each of the three nutrients, the mechanism of digestion is different, and further the mechanism of absorption and metabolism is different. Apart from small stories, it is important to keep that big flow down.

● Carbohydrates that can be digested are limited

Now, depending on the textbook in Japan, “sugar substance”, lipid, protein are cited as three major nutrients. But is sugar substance and carbohydrate the same? Sugar as nutrient is said to be carbohydrate in English translation, so it seems to be the same thing. However, it is stated in Japanese “Nutrition Labeling Standard” that “amount of carbohydrate” can be replaced with “amount of sugar substance and dietary fiber”. If so, in Japan it seems that “sugar substance” is regarded as a carbohydrate other than dietary fiber.　

“Dietary fiber” is a term that collectively refers to carbohydrates that human digestive enzymes do not work and are not digested by human power. In Japan, carbohydrates that humans can digest are called “sugar substance”. Dare to express it in English, it seems to be “nutritional carbohydrate”.

Anyway, of carbohydrates entering human mouth, there are not many that can be digested. In polysaccharide, both starch and glycogen, which is a polymer of glucose, can be digested. In addition, only three types of disaccharide can be digested, sucrose, maltose, lactose.
Cellulose, which occupies about half of the dry weight of vegetables, is a substance making cell walls of plants, like carbohydrates like cousins of starch. However, humans do not have digestive enzymes that break down cellulose. Therefore, it can not be digested.　However, part of dietary fiber is gaining attention at this time because intestinal bacteria that aid intestinal activity are digested. These are digested and decomposed by bacteria, absorbed as lactic acid, acetic acid, etc, so it seems that there is reasonable nutritional value.

● Carbon and lipid are energy masses

The carbohydrates and lipids are the same for the three kinds of carbon C, oxygen O, and hydrogen H. Carbohydrates have a large amount of oxygen and lipids have very little oxygen. The more important difference is that carbohydrates are more likely to contain water and lipids repel water due to the difference in elemental connection. Both are important as a mass of energy used in the body via adenosine triphosphate (ATP), but lipids of the same energy quantity are more suitable for storage because they are lighter than carbohydrates. Instead, carbohydrates are advantageous in that they are easier to extract energy than lipids. Relationship with water is totally different, there are also great differences in digestion and absorption methods when it is taken into the body.

● Protein has nitrogen

On the other hand, proteins are used as a material for creating new proteins in the body rather than as energy. Protein is a macromolecule made by joining together 20 kinds of amino acids in order of various combinations. Since each amino acid always has nitrogen N in addition to carbon, oxygen and hydrogen, the protein contains a large amount of nitrogen N. About 20 kinds of amino acids used for protein synthesis, about half can be made from other amino acids etc. However, the remaining half, nine can not be made in the human body, so it is called essential amino acids. “Essential” means that you must take it as a nutrient. Protein is familiar with water, so digestion and absorption methods are somewhat similar to carbohydrates.

● Digestive enzymes work in aqueous solution

met-intest.gifStarch and glycogen are mainly degraded into disaccharide maltose by digestive enzyme attack directly in the small intestine aqueous solution. After that, it is separated by enzymes on the surface of the cell membrane of the small intestine wall and becomes glucose, which is immediately incorporated into small intestinal epithelial cells. Since carbohydrates are repelled by phospholipid-made cell membranes, a dedicated carrier is required for uptake.

On the other hand, the digested lipid basically takes the form of neutral fats in which glycerin and a fatty acid are combined and decomposes in the aqueous solution of the small intestine also under the attack of digestive enzymes. However, since neutral fat repels water, digestion must be assisted by a bile that acts to improve the affinity of lipids and water for the enzyme to work. Instead, when in contact with the cell membrane, fatty acid and glycerin pass through the cell membrane with simple diffusion.

Proteins are first appropriately chopped with digestive enzymes in a strongly acidic aqueous solution of the stomach. After that, it is attacked by a new digestive enzyme in the small intestine, and it is broken down into a small peptide made of two to several amino acids. After that, it is eventually separated into individual amino acids on the cell membrane surface and is immediately absorbed into epithelial cells. Absorption of amino acids is similar to that of monosaccharides, carried by carriers dedicated to amino acids in the cell membrane.

● Monosaccharides and amino acids move directly to the liver

The monosaccharides and amino acids taken in the small intestinal epithelial cells pass through the back door of the cell as it is (there is also a dedicated carrier here), and it is picked up by capillary vessels running sideways. After that, it passes through the portal vein, reaches the liver, where it is processed. met-lever.gif

Meanwhile, glycerin and fatty acid taken in the cell are reconstituted as new neutral fat in the cell, and this time it is packed as chylomicron, and it escapes from the back of the cell. Basically, chylomicrons are picked up by capillary lymphatic vessels, concentrated in the lymphatic system and join the vena cava by the heart, so they do not pass through the liver, go through the systemic circulation through pulmonary circulation. I do not fully understand what it means. Anyway, around the tissue that needs lipid, various lipids including chylomicron after exchanging with cells are finally handled around the liver and processed. Small fatty acids not entering chylomicron are said to move directly from the capillary to the liver。

● Carbohydrates and fatty acids are accumulated or decomposed as needed

A part of glucose which occupies most of the monosaccharides flowing through the blood is used as it is as the sole energy source of brains and blood cells (erythrocyte). The remaining part is taken into the liver and muscle cells, and as glycogen, if it has room, it is taken into adipose tissue and turns into neutral fat, and it accumulates as an inventory of energy source until it becomes necessary. Lipids flowing through the blood are used as energy sources for the muscles and the heart that are always putting strength, and if this is also affordable, it accumulates as neutral fat with adipose tissue as it is. As with the carbohydrates, surplus amino acids are converted into fatty acids and accumulated in the liver.

The time when you are hungry between meals and meals uses the stored glycogen and neutral fats in order. met-muscl2.gifHowever, muscle glycogen is used by the muscle itself, whereas the liver does not use glycogen as its own energy source. Because liver glycogen is a source of glucose needed for brain activity. The liver itself takes out the necessary energy using fatty acids and amino acids while conducting very complicated metabolic activities whether it is meal or hungry.

● Amino acids turn into proteins and other substances

Amino acids are taken up by cells of the whole body and used as a material of proteins to maintain cell functions such as the skeleton of each cell and enzymes and receptors. Especially in the muscle a large amount of protein for muscle contraction such as actin and myosin is made. In the liver, we make various plasma proteins including albumin. Although it is not limited to protein, any substance of the body is made, while it is being destroyed more and more. Proteins are also returned to each amino acid again. Compounds containing nitrogen N, including surplus amino acids, can be converted to substances for excretion such as urea, ultimately by extracting energy, converting to sugar or fat, through liver metabolism.

● Absorbed nutrients get lost by dissipating energy

The source material from which energy is extracted has a basic structure of carbon and hydrogen skeletons. The simplest structure is methane (CH4), which is not a constituent of the human body, but if you apply oxygen it burns and burns (explodes). It radiates energy. As a result, water without energy H2O and carbon dioxide CO2 is completed.
CH4 + 2O2 -> CO2 + 2H2O + energy
The metabolism of the human body, in short, is the same.The representative monosaccharide of energy source is C6H12O6, and oxygen is partially bound from the beginning. And because it is not a gas, it is easy to handle. In the body, the work to extract energy is carried out gradually so that it does not explode at once.
C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy　
As well as neutral fat, when amino acids are stripped of nitrogen, eventually it will become water and carbon dioxide if energy is extracted. Nitrogen does not leave the body with the form of gas. Unlike carbon dioxide, the amount of nitrogen gas that occupies about 80% of the air is too large and it is difficult to excrete.

● Nutrients after use are spilled out of the body in the form of residual slag

In other words, after eating rice, bread and meat lumps, the contents of the feces coming out of the body, apart from water accounting for 80%, are mostly dietary fiber and enterobacteria, such as intestinal bacteria which were not originally absorbed materials. One third of the mass seems to be a remnant of cells detached from the intestinal wall. The water of stool is about 4% of the water exhaled from the body, in other words, the masses coming out of the large intestine are mostly not decomposition metabolized in the body. met-breath.gifNutrients used for the body disappears as energy such as carbon dioxide discharged from the mouth and urine and perspiration after it is extracted. The source of urine nitrogen compounds is protein nitrogen. Energy is used as a driving force to synthesize, destroy or move substances of the body, but eventually it escapes from the surface of the body while maintaining body temperature as heat.met-urea.gif　

Aside from the period of growth from children to adults, the incoming coming out, so there is nothing left in the end. Even though the life that was born originally grew, it surely disappears by the end. The preciousness of life seems to be in the process of exchanging matter and energy itself, which never stops moving during that process. On that basis, “culture” and “information” may be produced from a part of the energy consumed by humans, but unfortunately we do not know how to estimate it.

○ Referenced sites

Nutrition labeling standard (Notification No. 176 of Ministry of Health, Labor and Welfare, 2003) – Consumer Agency
Enteral nutrition, clinical nutrition understood by keyword, Newtory Co., Ltd.
Urea circuit, medicine of lipid and thrombus
Pooch is made of what, how to know the intestinal environment from poo, Taiho Pharmaceutical

○ Related articles

[017] 糖質の吸収　absorption of carbohydratel
[027] ペプチド結合 peptide bond
[032] グリコーゲンの合成 glycogen synthesis
[047] glycolysis
[042] ＴＣＡ回路 TCA cycle
[019] アデノシン三リン酸（ATP) adenosine triphosphate
[050] Cellular respiration
[001] Heartbeat pumping
[016] 血液循環　blood circulation
[026] interaction of myosin and actin
[003] Diaphragmatic breathing
[015] 胸式呼吸　costal breathing
[023] 赤血球とヘモグロビン　erythrocyte and hemoglobin
[043] 糸球体のろ過 glomerular filtration

○Referenced books


rev.20151225，rev.20160123, rev.20170506, rev.20170520，rev.20180709.

[045] Arteriovenous anastomoses in skin (GB#103B05) Mon, 17 Nov 2014 13:16:43 +0000 arteriovenous anastomoses
● The heart is warm in people with cold hands

When I was a child, a few friends were saying something like this. Actually, even in English, it says, there is an old proverb of “Cold hands, warm heart.” Is it common in the world, at least, to separate people with cold hands and those with warm hands? The difference in hand temperature, that is, the difference in body heat dissipation. When the hands are cold it means that there is little heat dissipation from the hands, so that the heat gets buried inside the body, maybe the “heart” is also warm?

● Heat comes in blood

Even a warm hand does not produce that heat in the palm of the hand. The main source of heat is the internal organs of the body which is constantly and actively metabolizing. Heat produced there heats the blood, it is carried to the end of the body through the blood, and finally it is dissipated from the surface of the body, out of the skin, while maintaining the body temperature of each place. Even with cold hand people, the mechanism is not different. Heat is dissipated from the skin of the whole body, but those with cold hands at least have less heat dissipated from the palm than the person with warm hands.

● The body is wrapped in subcutaneous fat

Roughly speaking, the skin consists of epidermis, dermis and subcutaneous tissue from the outermost side. The blood vessels are running to the dermis, and the epidermis has no blood vessels. Frequently talked about, “subcutaneous fat” is “adipose tissue” accumulated in subcutaneous tissue. Perhaps from the meaning “under the skin”, it may not be included in “skin”, but there is no clear boundary layer between the dermis and subcutaneous tissue, and the adipose tissue is always underneath the dermis all the time. Although the epidermis and dermis total no more than 2 mm in thickness, subcutaneous tissue is many times that number. Although there are considerable differences depending on the location, most of the thickness thought that this is the skin by pinching with the finger should actually be due to the subcutaneous tissue.

● There is a blood vessel rich dermis on the outer side of adipose tissue

Subcutaneous fat is said to have a high adiabatic effect. Actually, it seems that the conductivity is at most one half of that of water of the same thickness, so it is not so high insulation effect. Even so, if you thicken the layer of fat, there will be less heat transfer than a thin layer of water-rich cells, and to some extent will act as a thermal insulator. Therefore, once the human body is wrapped in a soft heat preservative, the whole body is made. arteriovenous anastomoses It is like wrapping up the sweet potatoes with dried newspaper in Japan. However, in the human body, the blood vessels penetrate the heat retention agent, and outside of it again, a dermal layer rich in blood vessels is made. There are no blood vessels in the outer layer of the dermis so as not to bleed easily, but the cells of the epidermis proliferate actively and must be replaced, so that the abundance of blood vessels is indispensable just below the epidermis.

● While keeping warm to some extent, regulate heat release

Since blood vessels of the skin spread out of the heat retardant, blood circulating the dermis can easily dissipate heat to the surface of the skin unlike when it is under the heat retardant. In other words, the skin has a dual structure consisting of an inner layer that is hard to dissipate heat and a surface layer that is easy to escape. This is an important point of the skin’s work on regulating body temperature.

With this structure, as the amount of blood circulating in the skin increases, more heat escapes outside the body, and as the amount of blood decreases, the role of a heat retardant acts to make it difficult for heat to escape from the body. Skin blood vessels actually expand when the inside of the body gets hot and need to escape the heat, and the blood flow becomes many times more. On the contrary, when it is cold and you have to keep your body temperature, in extreme cases, at least the blood flow in the surface layer will decrease to a point where it stops. Tissue thermal conductivity also varies with temperature. As the temperature decreases, the thermal conductivity of water-rich tissues increases, while the thermal conductivity of fat seems to be low. Therefore, the role of subcutaneous fat to the heat retention effect further increases.

Conversely, it is also known that when the temperature outside the body is high and the surface temperature of the skin becomes higher than the body temperature, skin blood vessels contract to suppress blood flow. It is a natural reaction if it is a purpose to keep the temperature inside the body normal.

● Special adjustment devices are in hand

The most important function of blood vessels is to bring fresh blood, arterial blood to the capillaries of the tissues of every corner of the body and to recover what the tissue throws away from there instead.　So it is the principle that the flow of blood vessels is followed by arteries ⇒ capillaries ⇒ veins. But in some parts of the body, especially the palms and fingers, the soles and fingers of the feet, the lips and cheeks, ears, etc., there are many direct connections of the arteries and veins that jumped capillaries in the dermis of the skin. This direct connections is called “arteriovenous anastomosis” of the skin. arteriovenous anastomosesSince it is a long word in English, it is often written with “AVA”, an abbreviation that is too simple and meaningless to grasp. Actually, there seems to be plenty still unclear parts, but skin AVA is regarded as a special device to regulate the dissipation of heat, which is also introduced in textbooks. However, it is too easy to explain, so usually you do not understand the meaning well.

● Arteriovenous anastomosis flush a large amount of blood

Peripheral blood vessels leading to capillaries basically undergo innervation of the sympathetic nerve. When the nerve activity is high, the smooth muscle of the blood vessel contracts to suppress the blood flow, and conversely, when relaxing the blood vessel suppresses the nerve activity. The arteriovenous anastomosis of the skin is mostly in the deep layer of the dermis, the smooth muscle surrounds it much more thickly than other surrounding blood vessels, and the innervation of the sympathetic nerve is also specially abundant. Especially if it is not hot or cold, this arteriovenous anastomosis seems to be closed. At that time, the blood normally circulates through the capillaries of the layer closer to the epidermis.

When it gets to rise in body temperature and become necessary to dissipate heat outside, sympathetic activity controlling this blood vessel is suppressed and arteriovenous anastomosis opens. As the whole blood vessel expands, the blood flow of the capillary vessel also increases, but blood passing through the arteriovenous anastomosis does not go to the capillary blood vessel, but only heat is discharged and it flows immediately into the vein. The arteriovenous anastomosis is said to be capable of flowing blood up to 200 times or 500 times the amount flowing through the capillary.

● Arteriovenous anastomosis opens even when cold?

arteriovenous anastomosesWhen exposed to a cold environment the blood vessels of the skin contract to reduce blood flow. It is to prevent the heat in the body from escaping. However, suppression of the circulation of the skin is a severe way of life and death for cells of the skin, while heat is difficult to escape.Since the metabolism of the cells falls at low temperature, it becomes strong against ischemic condition. But prolonging it is still a disadvantage. In such a case, depending on the part of the body, blood vessels of the skin sometimes open arbitrarily and resume blood flow temporarily.

If the temperature is low enough to stop the circulation, excitatory conduction of the nerve fibers is also blocked, so the effect of the sympathetic nerve that closed the blood vessel disappears, and whether the smooth muscle relaxes arbitrarily. It seems that when the blood flow resumes, the temperature of the tissue rises, when the nerve activity revives, the blood vessels contract, the circulation is suppressed, and the tissue cools again. (Actually it does not go well, it gets burned or frostbite.)

●Is the arteriovenous anastomosis of the skin effective?

Arteriovenous anastomosis is thought to be strongly related to temperature regulation, but its place has not spread throughout the body. There seems to be almost no AVA in a place that hides in the wet suit of diving.To be more precise, if you think about the body of the monkey, it is not in a place covered with hair, it is confined to a narrow place without body hair. Even if it is on the skin where the hair is covered tightly, it can not expect much heat dissipation effect, so it will be good. Originally other than humans, sweat glands are not in the part with body hair. Although the sweat glands spread throughout the body in humans, the arteriovenous anastomosis is like taking over the ancestral distribution almost as it is. How does human’s arteriovenous anastomosis of hand have meaning in thermoregulation? Calculating roughly the effect of the area, the area of both hands is about 300 cm2 in total, while the body surface area of the whole body is about 16000 cm2. There is only about 2% influence. Apparently, for people, it seems more important that “the effect of warming the hand” is more important.

● If you take out heat from your hands, will your body cool?

Even though the arteriovenous anastomosis of the hand works the maximum, the hand will warm but the body temperature does not seem to drop as much as we thought. The palms and soles of the feet are described in physiology textbooks as places where “thermal sweating” does not occur. Sweating in your hands is a phenomenon when you feel dizzy, such as shaking. This is mental sweating. So even if your body temperature rises and heat is transferred to the skin of the hand, there is no sweat, so the hand will get hot, but not much heat will escape. It is natural that air is much more adiabatic than fat.

However, for example, when you immerse your hands wrapped in running water it will be completely different. The excess heat will steadily conduct and escape to the water that touched the skin. If you accidentally immerse your hand in ice water, physiological reactions such as vasoconstriction will occur and impede heat dissipation, so water that is not too cold is an important. In the university of the United States, using this effect, a device for rapidly cooling the whole body temperature with only one hand has been developed and commercialized. Perhaps, most of the time, hands are being thrown into the air is a human being, other ordinary animals are always wearing forelimbs and hind legs on the ground, or living with something grabbing, there is no doubt that the adjustment of the heat dissipation in the skin works much more effectively.

● Is there a difference in the temperature of hands by humans?

When examining around us, it was true that some people with hands are warm, some have cold hands. The warm group is roughly 33 °C to 34 °C, the cold group is around 27 °C to 28 °C, and the two groups are not consecutive (Room temperature 23 °C, using AS ONE infrared radiation thermometer ISK-8700ii). Because there is a difference of 5 °C, from the warmest hand it feels like the lower temperature hand is clearly cold. The number of people was more warm, at least it seemed like a minority of cold hands around me, but unfortunately it was impossible to judge whether the hearts of these people were warm at ISK-8700. For myself, the temperature of the hands sometimes falls to about 30 °C for no reason, but at about 33 °C it enters a group of warm hands. Even though there are people with hypothermia, body temperature is not different by 5 °C. So, if your hands are warm, the blood vessels of your skin tend to loosen on average, and that your hands are cold means that it will be narrowed on average. Whether the hands are warm or cold, but the body temperature is about the same, the hands are always warm may seem to dissipate a little wasteful energy.

● Do people with cold hands tend to take warm actions?

A while ago in the American science magazine, the result of a certain psychological experiment was becoming a topic.　Roughly summarizing the experiment itself,When touching a warm thing with a hand, it is easy to judge a person in front of you as a warm person unconsciously, and if you choose something to receive at that time, the tendency to choose for friends rather than for themselves is there. On the other hand, when touching a cold thing, it is the reverse, and it tends to make selfish judgment unconsciously. This report is quoted in several other magazines and so forth. There, psychologically, if you touch a person with a cold hand, you do not have a good feeling for that person. Therefore, it seems that the phrase “Cold hands, warm heart” to be interpreted as something like the wisdom of social life which dares to cancel it.

Although the original authors who reported the experiments did not mention this legend at all, it would be unnecessary care, what we can say honestly from this report is that “People will do warm actions to others if they have a warm experience.” People with cold hands often have opportunities to touch warm people and warm objects than hands compared to warm people. Does that mean that the people are more likely to take a warm act warmly? Then, as a result, “The person with cold hands is warm hearted” . . That’s it!

○ Referenced sites

Arterio-Venous Anastomoses and Thermoregulation (1991)(pdf)
The Anatomy and Histochemistry of the Arteriovenous Anastomosis in Human Digital Skin.(1956) (pdf)
・食品の熱伝導度，(リンク元削除，2017-7-4)　⇒　食品科学便覧,共立出版（株）,食品科学便覧編集委員会編参照
AVAcore Technologies and CoreControl.
Experiencing Physical Warmth Promotes Interpersonal Warmth, Williams and Bargh, SCIENCE, 2008.
A More Social Explanation of “Cold Hands, Warm Heart”, Krystal D’Costa, Scientific American, 2012.
気温 38℃は暑いのに，38℃のお風呂はなぜ熱くないのか, 自然科学コンクール第43回入賞作品中学校の部文部科学大臣奨励賞，2002. 。
同じ 33℃で気温は暑く水温は冷たいのはなぜ, 日常の化学工学, 化学工学資料のページ
日本人の体表面積, 暴露係数ハンドブック, 独立行政法人産業技術総合研究所.(pdf)

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[038] 深部体温の恒常性 homeostasis of the core body temperature 041-heartmuscle80.gif
[048] Epidermal cell turnover　
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[033] 平滑筋の収縮 smooth muscle contraction
[016] 血液循環　blood circulation
[001] Heartbeat pumping

○ Referenced books


rev.20141119，rev.20141211，rev.20160422，rev.20170506, rev.20170716, rev.20170921, rev.20171025, rev.20180304.