1.3: Medication safety- to ‘error’ is human
Medication safety
At the end of this case, students will be able to:
- Define medication-use safety and the importance to public health
- Identify risk factors associated with medication safety and reasons for unsafe medication use in elderly patients
- Examine the pharmacist’s role and tools used to improve medication safety
- Recommend resources pharmacists can provide to patients with physical impairments to overcome medication-related issues
- Recommend a plan of action using the Medication Appropriateness Index (MAI)
Introduction
Medication use safety is an important aspect of the healthcare delivery system to consider in all patients as it can affect the patient’s overall health at home and within the healthcare system. When thinking about this issue, it is common to consider the use of medication in specific populations (such as elderly patients), language barriers, adverse drug events (ADE), drug shortages, and acquisition of medications.
ADEs often result from unsafe medication use, leading to more than one million visits to the emergency room and 350,000 hospitalizations on an annual basis. 1 Billions of dollars are spent addressing ADEs, with the elderly population particularly at risk. 2-4 Reasons for this include physiologic changes, health literacy barriers, health disparities, polypharmacy, and nonadherence. Nonadherence can be intentional or unintentional and affected by medication efficacy, perceptions of one’s health or illness, or cultural beliefs. 5 The inherent nature of medications can also predispose patients to ADEs. 4 ,6 Although not limited to the elderly, physical impairments can also result in medication nonadherence and ADEs. Impairments can include, but are not limited to, dexterity, vision, mental status, and hearing.
Due to the large impact on public health, pharmacists have access to many tools and resources that have been developed to prevent and resolve ADEs. For example, many medications that may be unsafe for older adults (e.g., anticholinergics, antihypertensives, antipsychotics, insulin, and sedatives) exist on the Beers Criteria for Medication Use in Older Adults . 7 Pharmacists can use these criteria to determine the appropriateness of an older adult patient’s medication regimen and seek alternative therapeutic choices. As one of the most widely used resources, the Criteria is regularly updated based on the most current research to support the safe and effective use of the listed medications along with corresponding strengths of recommendation. The combination of the Screening Tool of Older People’s Prescriptions (STOPP) and Screening Tool to Alert to Right Treatment (START) criteria can also be used to determine potentially inappropriate prescribing in older adults while offering treatment alternatives. 8 The Medication Appropriateness Index (MAI) is another tool that can be used to prevent ADEs; this tool consists of 10 questions that a pharmacist may ask regarding each drug a patient is taking. 9 The questionnaire assesses a medication’s indication, effectiveness, dose, directions for use, administration, interactions, duration of use, and cost. Based on a score ranging between 0 and 18, the MAI provides a final rating of appropriateness: appropriate, marginally appropriate, or inappropriate. Additional screening tools and scales used to assess a patient’s understanding of medications and diseases include the Drug Regimen Unassisted Grading Scale (DRUGS), Medication Management Instrument for Deficiencies in the Elderly (MedMaIDE), Medi-COG, and the Self-Administration of Medication (SAM). 10 ,11,12
Case
You are a pharmacist working in a family medicine clinic.
CC: “I need a refill on my shots”
HPI: GR is a 79-year-old female patient (65 in, 77 kg) presenting to her family medicine clinic for follow-up for her chronic disease states. The patient has been in India the past four months with family members and indicates no healthcare concerns at this time. She reports no hypoglycemic events and states that her blood sugar levels are “good”. The patient did not bring her blood glucose log to clinic.
PMH: T2DM; HTN; HLD; severe osteoarthritis in her hands
FH:
- Mother: T2DM, breast cancer
- Father: MI at age 57
Medications:
- Metformin 500 mg BID
- Insulin glargine 42 units SQ at bedtime (vials and syringes for insurance purposes)
- Glyburide 10 mg daily
- Atorvastatin 80 mg daily
- Lisinopril 20 mg daily
- Hydrochlorothiazide 25 mg daily
- Acetaminophen 500 mg four times daily as needed for pain
Labs:
- Na 140 mmol/L
- K 4.2 mmol/L
- Cl 101 mmol/L
- CO 2 27 mmol/L
- BUN 16 mg/dL
- SCr 0.92 mg/dL
- Ca 9.6 mg/dL
- Glucose 148 mg/dL
- HgA1c 9.1%
- LDL 98 mg/dL
- HDL 41 mg/dL
- Triglycerides 137 mg/dL
- Total cholesterol 166 mg/dL
- Alk phos 64 U/L
- AST 25 U/L
- ALT 32 U/L
VS:
- BP 138/72 mmHg
- HR 84 bpm
- RR 12/min
SDH: Because GR’s English proficiency is low, she is accompanied by her son to her appointment to aid in translation.
Additional context: Upon interviewing the patient (by way of her son), you found that she ran out of her insulin glargine while she was in India. While in India, her nephew ordered insulin online from an internet pharmacy because the pharmacy she normally uses could not acquire the medication due to a current shortage. She also states that her nephew thinks that she should be cooking with extra turmeric and cinnamon to help with her diseases rather than using the “chemicals” found in medications.
Case Questions
- Identify and describe the areas of increased medication safety concern for this patient.
- Based on the MAI , which medication is least appropriate for this patient? How should this be addressed?
- How would you address her statement about her nephew’s beliefs in the use of turmeric and cinnamon instead of her prescription medications?
- The patient’s insulin glargine is currently on back order due to a medication shortage. What are some of the resources the pharmacist could turn to gather information on this shortage?
- Because the patient’s son bought her insulin online, this medication is at high risk of being counterfeit. What is the most common source of counterfeit medication? Identify the safety concerns related to counterfeit medication use.
Author Commentary
Pharmacists are the key professionals positioned to address medication safety by ensuring appropriate prescribing, dispensing, administration, lab monitoring, and adherence. Drug shortages may also cause a number of safety concerns through delays in treatment that may compromise clinical outcomes. 13 Drug shortages have also been linked to medication errors and an increase in adverse events and death. 13,14 Counterfeit medications may arise due to difficulty in acquiring medications such as drug shortages, high costs for the patient, convenience of internet pharmacies, and breakdowns in the medication supply chains. 15 Counterfeit medications have been shown to present as safety concerns for patients, and multiple instances have occurred where purported ‘medications’ have no active ingredient whatsoever. 15 Other safety concerns include the addition of harmful substances (bacteria-laced water, paint, floor wax, boric acid, powdered cement, and antifreeze), incorrect active ingredient in the product, and wrong concentration or dose. 15-18 Internet pharmacies are the primary source of counterfeit medications, and many patients do not know the dangers. 19 Many companies claim that the medications are being manufactured in Canada, but this has been proven to be false. They often provide medications that are not approved by the FDA or Canadian government. Sadly, there have even been links to terror organizations. 15
The FDA and ASHP have excellent resources available on their websites that display current drug shortages, reasons for shortage, expected availability and available products. 20 ,21
Patient Approaches and Opportunities
Pharmacists are uniquely positioned to identify medication safety issues, decrease patients’ risk for adverse drug events, and improve the patient experience and outcomes. Community pharmacists often encounter patients with physical impairments and can provide resources to overcome medication-related issues and nonadherence. For patients with osteoarthritis, rheumatoid arthritis, lupus, or other conditions that challenge the use of hands and fingers, the following items may be suggested: prefilled blister packs, easy-open caps, easy-open pill extractors, bottle openers, spacer for inhalers, and eye drop guides. For patients who have trouble seeing, pharmacists may provide medication guides or educational pamphlets in larger print, have instructions/counseling spoken aloud, use color coding, or use talking devices. Patients who have trouble hearing instructions can use hearing aids, visual/written aids, or a TeleTYpe (TTY) device.
As the medication experts, pharmacists are also positioned to regularly conduct medication reconciliation to ensure accurate medication lists and work within an interprofessional team to ensure safe and effective use of medications. 22
Related chapters of interest
- Safe opioid use in the community setting: reverse the curse?
- Saying what you mean doesn’t always mean what you say: cross-cultural communication
- More than just diet and exercise: social determinants of health and well-being
- Equity for all: providing accessible healthcare for patients living with disabilities
- Deprescribing in palliative care: applying knowledge translation strategies
External resources
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Websites:
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FDA Drug Shortages.
https://www.fda.gov/drugs/drugsafety/drugshortages/default.htm - ASHP Drug Shortages. https://www.ashp.org/drug-shortages/current-shortages
- Institute for Safe Medication Practices – https://www.ismp.org/
- Consumer Med Safety – http://www.consumermedsafety.org/
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Patient reporting of suspicious internet pharmacies –
https://nabp.pharmacy/programs/vipps/vipps-accredited-pharmacies-list/ .
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FDA Drug Shortages.
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Journal Articles
- Beers Criteria: American Geriatrics Society 2019 Beers Criteria Update Expert Panel. American Geriatrics Society 2019 updated Beers criteria for potentially inappropriate medication use in older adults. J Am Geriatr Soc . 2019;67(4):674-694.
- START/STOPP Criteria: O’Mahony D; O’Sullivan D ; Byrne S; et al. STOPP/START criteria for potentially inappropriate prescribing in older people: version 2. Age Ageing . 2015; 44: 213-218.
- Medication Appropriateness Index: Hanlon et al. A method for assessing drug therapy appropriateness. J Clin Epidemiol . 1992,45:1045-51.
References
- Shehab N, Lovegrove MC, Geller AI, Rose KO, Weidle NJ, Budnitz DS. US emergency department visits for outpatient adverse drug events, 2013-2014. JAMA 2016;316:2115-25.
- Institute of Medicine. Committee on Identifying and Preventing Medication Errors. Preventing Medication Errors, Washington, DC: The National Academies Press 2006.
- Hajjar E, Hanlon JT, Artz MB, et al. Adverse drug reaction risk factors in older outpatients. Am J GeriatrPharmacother . 2003; 1:82-89.
- Field TS, Gurwitz JH, Harrold LR, et al. Risk Factors for Adverse Drug Events Among Older Adults in the Ambulatory Setting. J Am Geriatr Soc . 2004; 52:1349–1354.
- Chia L, Schlenk EA, Dunbar-Jacob J. Effect of personal and cultural beliefs on medication adherence in the elderly. Drugs Aging . 2006;23(30: 191-202
- Pretorius RW, Gataric G, Swedlund SK, Miller JR. Reducing the Risk of Adverse Drug Events in Older Adults. Am Fam Physician . 2013;87(5):331-336.
- American Geriatrics Society 2019 Beers Criteria Update Expert Panel. American Geriatrics Society 2019 updated Beers criteria for potentially inappropriate medication use in older adults. J Am Geriatr Soc . 2019;67(4):674-694.


1.5: Emotions and Feelings are Broad Thoughts
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A thought is thinking about something in specific. You can have a thought about an entire paragraph, but it is going to be just a thought, it is going to be about one thing, and that one thing might be a summary of the paragraph - but it is still a thought. So what we think of as thought is really just a short period of thinking - one unit of thinking that lasts for a short period of time. An essay is composed of many thoughts, but just one thought would be “I went to the store”.
Then again, “I went to the store, and Jason followed me” might be considered one thought as well. So how long exactly is a thought? If it is longer than “I went to the store, and Jason followed me” then it is probably going to be considered multiple thoughts. Thus humans use the word thought as just a short period of time in thinking.
Thoughts are in general talked about as being verbal, people rarely think of emotions and feelings as thoughts. But emotions and feelings are thoughts if you think about that emotion and feeling. The short period of time in which you think about the emotion or feeling is a thought. So thoughts can be about emotions and feelings. They are just harder to identify because they aren’t verbal.
The reason that verbal things are easier to identify is because they are distinct sounds (that we have definitions for). Distinct sounds, different sounds, are easy to separate. It is easy to identify one sound from another sound, and that is all words are, different sounds. So it could be that someone is talking and you don’t have any thoughts about them talking, or you are not thinking about them talking. In that case you just aren’t listening to them, or you are not paying attention to the sounds they are making.
So thought then is really just any short period of high attention. And thinking is long or short periods of high attention. So if you are thinking for more than a few seconds, then you are probably going to be thinking about several thoughts. Since you can think about emotions and feelings too, however, you can think about your emotions or feelings for long periods of time.
Just as thinking is made up of individual components of thought, feeling, or emotion, each of those components is made up of their own further components. In fact, when you think about an emotion or feeling you intensify that feeling or emotion a lot.  The real world can include thoughts and feelings in your head as well.
So emotions, feelings and thoughts are made up of real experiences. A thought isn’t just a thing in your head, but it is something that has components that are real in the world. Those things might be sounds (when you think about someone speaking, you make that sound in your head).  Just try it and think about any sound, it produces the same emotions as when the sound itself occurred outside your head.
So a thought in the end boils down to you thinking about sensations, any sensation, taste, touch, sound, smell, feeling, or emotion. How can a thought be of emotion? Aren’t thoughts supposed to be specific and quantifiable? Well a thought about an emotion is basically a summary of that emotion. If you played Frisbee and you get an emotion from playing Frisbee, then that emotion is a summary of the things in which you remember about playing Frisbee. The same goes with feelings. The feeling you have about something is really all the feelings that that thing causes in you, and when you focus on different aspects of that feeling, you are focusing on different aspects of the real experience which caused the feeling.
So when you think about an emotion you are intensifying the feeling of those real experiences. You have no conscious idea of which parts of the feeling you are thinking about, however. Maybe if you think about directly different parts of the real experience you can link it up to different parts of its emotion.
Thus any emotion or feeling can be broken down into the sensations and real events that caused it. And you can think about any of those things (with thoughts). You can also think about those things as individual thoughts.  Your natural attention span varies, but if you think about something you can boost that attention, you are trying to boost that attention on something specific or something broad (like an emotion).
Emotions and feelings are so intense, however, that it is like you are trying to focus your attention on them. So emotions, feelings, and thoughts are all periods of focused attention. A thought is just more focused attention than a feeling or emotion (unless it is a thought about a feeling or an emotion, in which case it is going to be even more attention than the feeling or thought or emotion by itself since it is a combination).
So emotions, feelings, and thoughts are all related, they are all things that you pay more attention to. And since emotion and feelings are made up of stuff which occurs in the real world, you could label each one of those things which occurs in the real world a thought, and say that emotions are made up of thoughts, or are broad thoughts.
What then is the difference between a thought and an emotion? Emotions are usually more intense and therefore last longer in your brain when you think about them, or “bring them up”. You usually can only bring them up by thinking about them, however. Other things might bring up an emotion, like other emotions or other feelings, consciously or unconsciously. The same with feelings and thoughts.
People "bring up" emotions, feelings and thoughts in various ways. One way to bring up an emotion would be using thought, such as thinking "I like my dog" would bring up the emotion of the dog. You could also think directly about the emotion of the dog without using the verbal discourse, however. This could also be described as just "feeling", "feeling out" or "being emotional about" your dog. A feeling could also bring up a thought (and all the other combinations of "bringing up" between thoughts, feelings and emotions). They might also be concurrent, that is, when you have one emotion there is an associated feeling with it (and the other combinations of that with feelings, thoughts and emotions). Don't forget that one of those combinations is that thoughts can also bring up or be concurrent with other thoughts (as with feelings and emotions).


26.3F: Accessory Sex Glands
The accessory sex glands produce seminal fluid and clean and lubricate the urethra.
- Describe the functions of male accessory sex glands
Key Points
- Seminal glands contain seminal vesicles that produce 50–70% of the seminal fluid.
- The excretory duct of the seminal gland opens into the vas deferens as it enters the prostate gland.
- Sperm are not in contact with the seminal fluid produced by the seminal vesicles, possibly to block the progress of sperm from other males.
- The prostate secretes 20–30% of the seminal fluid which carries the sperm in the ejaculate.
- The prostate surrounds the urethra below the bladder and can be felt in a rectal exam.
- Bulbourethral glands produce a pre-ejaculate secretion which lubricates and flushes out the urethra in preparation for the sperm.
Key Terms
- bulbourethral gland : An exocrine gland which secretes a clear fluid upon sexual arousal as pre-ejaculate (or Cowper’s fluid).
- Lipofuscin : Yellow-brown pigment granules composed of lipid-containing residues of lysosomal digestion.
- prostate : A compound tubuloalveolar exocrine gland of the male reproductive system in most mammals.
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seminal gland
: A pair of simple tubular glands located within the pelvis
that secrete fluid that partly composes semen.
The accessory sex glands, including the seminal, prostate glands, and bulbourethral glands, produce seminal fluid and clean and lubricate the urethra.
Seminal Gland Anatomy
Each seminal gland forms as an outward growth of the wall of ampulla of each vas deferens. They are curled and folded within the gland and can spread out to approximately 5 cm, but the unfolded length is approximately 10 cm. The excretory duct of the seminal gland opens into the vas deferens as it enters the prostate gland.
Seminal Gland Physiology and Function
The seminal vesicles secrete a significant proportion of the fluid that ultimately becomes semen. Lipofuscin granules from dead epithelial cells give the secretion its yellowish color. About 50–70% of seminal fluid in humans originates from the seminal vesicles, but is not expelled in the first ejaculate fractions which are dominated by spermatozoa and zinc-rich prostatic fluid. Seminal vesicle fluid is alkaline, resulting in human semen with a mildly alkaline pH. This helps neutralize the acidity of the vaginal tract, prolonging the lifespan of sperm. Acidic ejaculate (pH <7.2) may be associated with ejaculatory duct obstruction. The vesicle produces a substance that causes the semen to become sticky after ejaculation, thought to help keep the semen near the cervix.
The thick seminal vesicle secretions contain proteins (including enzymes), mucus, fructose, vitamin C, flavins, phosphorylcholine, and prostaglandins. The high fructose concentrations provide nutrient energy for the spermatozoa when stored in semen in the laboratory. Spermatozoa ejaculated into the vagina are not likely to have contact with seminal vesicular fluid, but transfer directly from the prostatic fluid into the cervical mucus as the first step on their travel through the female reproductive system.
Seminal vesicle fluid is expelled under sympathetic contraction of the muscularis muscle coat. In vitro studies have shown that sperm expelled together with seminal vesicular fluid show poor motility and survival and less-protected chromatin. Thus, the exact physiological importance of seminal vesicular fluid is unclear. It may be a developmental rest, such as in some rodents where the last part of the ejaculate forms a spermicidal plug to reduce the chances for sperm from a later-arriving male to proceed to the oocyte.
Prostate Gland Anatomy
Prostate : Prostate with seminal vesicles and seminal ducts, viewed from the front and above, including the urethra, seminal vesicle, vas deferens, ampulla, ejaculatory duct, and isthmus.
The prostate surrounds the urethra just below the urinary bladder and can be felt during a rectal exam. It is the only exocrine organ located in the midline in humans and similar animals. Within the prostate, the urethra coming from the bladder is called the prostatic urethra and merges with the two ejaculatory ducts. The prostate is sheathed in the muscles of the pelvic floor, which contract during the ejaculatory process.
Prostate Gland Physiology and Function
The prostate secretes a slightly acidic fluid, milky or white in appearance, that usually constitutes 20–30% of the volume of the semen along with spermatozoa and seminal vesicle fluid. The prostatic fluid is expelled in the first ejaculate fractions, together with most of the spermatozoa. In comparison with the few spermatozoa expelled in seminal vesicular fluid, those expelled in prostatic fluid have better motility, longer survival, and better protection of the genetic material. The prostate also contains some smooth muscles that help expel semen during ejaculation.
To work properly, the prostate needs male hormones (e.g., testosterone), which are produced mainly by the testes. Some male hormones are produced in small amounts by the adrenal glands. However, dihydrotestosterone regulates the prostate. A healthy human prostate is slightly larger than a walnut in adult males, with a weight ranging between 7 and 16 grams.
 The bulbourethral gland is labeled at center left.
Bulbourethral glands are located posterior and lateral to the membranous portion of the urethra at the base of the penis, between the two layers of the fascia of the urogenital diaphragm in the deep perineal pouch. They are enclosed by transverse fibers of the sphincter urethrae membranacea muscle. The bulbourethral glands are compound tubulo-alveolar glands, each approximately the size of a pea. They are composed of several lobules held together by a fibrous covering. Each lobule opens into a duct that joins with the ducts of other lobules to form a single excretory duct. This duct is approximately 2.5 cm long and opens into the urethra at the base of the penis. The glands gradually diminish in size with advancing age.
During sexual arousal, each gland produces a clear, salty, viscous secretion known as pre-ejaculate. This fluid helps to lubricate the urethra for spermatozoa to pass through, neutralizes traces of acidic urine in the urethra, and helps flush out any residual urine or foreign matter. It is possible for this fluid to pick up sperm remaining in the urethral bulb from previous ejaculations and carry them out prior to the next ejaculation.
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- Epididymis. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Epididymis . License : CC BY-SA: Attribution-ShareAlike
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- Male Reproductive System. Provided by : brookingsapbiology Wikispace. Located at : http://brookingsapbiology.wikispaces.com/Male+Reproductive+System . License : CC BY-SA: Attribution-ShareAlike
- spermatogenesis. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/spermatogenesis . License : CC BY-SA: Attribution-ShareAlike
- testosterone. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/testosterone . License : CC BY-SA: Attribution-ShareAlike
- male anatomymale anatomyKevin (tsaitgaist) REDON. Provided by : Wikimedia. Located at : upload.wikimedia.org/wikipedi...anatomy_en.svg . License : Public Domain: No Known Copyright
- Scrotum. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Scrotum . License : CC BY-SA: Attribution-ShareAlike
- epididymis. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/epididymis . License : CC BY-SA: Attribution-ShareAlike
- scrotum. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/scrotum . License : CC BY-SA: Attribution-ShareAlike
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- Figure 28 01 02.JPG. Provided by : Wikipedia Commons. Located at : commons.wikimedia.org/wiki/F...e_28_01_02.JPG . License : CC BY: Attribution
- Sertoli Cells. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Sertoli_cell . License : CC BY-SA: Attribution-ShareAlike
- Luteinizing Hormone. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Luteinizing_hormone . License : CC BY-SA: Attribution-ShareAlike
- Follicle-Stimulating Hormone. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Follic...cts_in_females . License : CC BY-SA: Attribution-ShareAlike
- Testicle. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Testicle . License : CC BY-SA: Attribution-ShareAlike
- Leydig cells. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Leydig%20cells . License : CC BY-SA: Attribution-ShareAlike
- testicle. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/testicle . License : CC BY-SA: Attribution-ShareAlike
- Boundless. Provided by : Boundless Learning. Located at : www.boundless.com//physiology...inition/testes . License : CC BY-SA: Attribution-ShareAlike
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- Gray1144. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/File:Gray1144.png . License : Public Domain: No Known Copyright
- Intromittent organ. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Intromittent_organ . License : CC BY-SA: Attribution-ShareAlike
- Clitoris. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Clitoris#Glans_and_body . License : CC BY-SA: Attribution-ShareAlike
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- ejaculation. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/ejaculation . License : CC BY-SA: Attribution-ShareAlike
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- Gray1144. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/File:Gray1144.png . License : Public Domain: No Known Copyright
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- Peristalsis. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Peristalsis . License : CC BY-SA: Attribution-ShareAlike
- Vas deferens. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Vas_deferens . License : CC BY-SA: Attribution-ShareAlike
- Seminiferous tubules. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Seminiferous_tubules . License : CC BY-SA: Attribution-ShareAlike
- Efferent ductules. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Efferent_ductules . License : CC BY-SA: Attribution-ShareAlike
- vasectomy. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/vasectomy . License : CC BY-SA: Attribution-ShareAlike
- vas deferens. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/vas_deferens . License : CC BY-SA: Attribution-ShareAlike
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- Gray1144. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/File:Gray1144.png . License : Public Domain: No Known Copyright
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- Prostate. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Prostate . License : CC BY-SA: Attribution-ShareAlike
- Boundless. Provided by : Boundless Learning. Located at : www.boundless.com//physiology.../seminal-gland . License : CC BY-SA: Attribution-ShareAlike
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20.14: Chapter 14 (Nutrition)
Answer Key to Chapter 14 Learning Activities
Scenario 1
- It would be important to assess Mr. Jones’s swallowing, bowel sounds, ability to pass flatus, abdominal distention, and any complaints of nausea.
- When transitioning the patient from NPO status, the patient would be started on clear liquids to ensure dietary tolerance prior to progression toward solid foods.
Scenario 2
- Mrs. Casey’s BMI is 15, placing her in the “Underweight” category since it is below 18.5.
- Mrs.  Magnesium levels may be low due to intake or can also be caused by excessive alcohol intake.
- The nurse should perform a general survey on Mrs. Casey, paying close attention to her energy level and mobility deficits as a result of the stroke. The nurse should ask Mrs. Casey about her typical 24-hour food intake, appetite, food allergies, and food shopping and preparation activities.
- Imbalanced Nutrition: Less than Body Requirements related to insufficient dietary intake as evidenced by BMI 15 and albumin level 10 g/mL.
- Mrs. Casey’s BMI will increase to at least 16 in the next month with a continued upward trend.
- The nurse will contact the provider and request a referral for a dietician. The nurse will contact the facility’s social worker regarding promoting nutritional intake with Meals on Wheels and other services. The nurse will monitor food/fluid ingested daily and caloric intake in collaboration with the dietician and encourage nutritional supplements as prescribed. The nurse will encourage the patient to select or order preferred foods for mealtimes. The nurse will ensure that oral care is performed before meals and that foods are presented in an attractive, pleasing manner. The patient will be placed in a seated position before eating, the meal tray set up, and assistance provided according to the patient’s needs.
- The nurse will evaluate the effectiveness of interventions by monitoring the patient’s weekly weights and assessing if her BMI is trending upward according to the previously established SMART goal.
Answers to interactive elements are given within the interactive element.


23.4: Dehydration of Aldol Products - Synthesis of Enones
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Objectives
After completing this section, you should be able to
- write an equation to illustrate the formation of a conjugated enone from a β ‑hydroxy aldehyde or ketone.
- write a detailed mechanism for the basic or acidic elimination of water from a β ‑hydroxy aldehyde or ketone.
- explain why β ‑hydroxy aldehydes and ketones undergo elimination reactions much more readily than most other alcohols.
- identify the enone products from the aldol condensation of a given aldehyde or ketone.
Study Notes
Conjugated enones, like conjugated dienes, have more inherent stability compared with their non‑conjugated counterparts. You may wish to review Section 14.1 on dienes, which gives a molecular orbital description showing π electron distribution over four atomic centres.
Note that both of the elimination mechanisms described here (acidic and basic) involve either the enol form or the enolate anion of the β ‑hydroxy carbonyl compound.
Aldol Condensation
Reactions in which a larger molecule is formed from smaller components, with the elimination of a very small by-product such as water are termed Condensations. Hence the following examples are properly referred to as aldol condensations.
Dehydration of Aldol Products to Synthesize α, β Unsaturated carbonyl (enones)
The products of aldol reactions, with heating, often undergo a subsequent elimination of water, made up from an alpha-hydrogen and the beta-hydroxyl group. The product of this acid or base-catalyzed E1cB elimination reaction (Section 11-10) reaction is an α,β-unsaturated aldehyde or ketone (Enones). Although there may be multiple position where the alkene may form, it will always prefer to be in conjugation with the carbonyl.
Conjugated enone products are more stable than non-conjugated due to extended P orbital overlap. Conjugation of the p electrons of the alkene and carbonyl bonds provide a molecular-orbital description showing the interaction of p electrons of all four atoms. The additional stability provided by the conjugated carbonyl system of the product makes many aldol reactions thermodynamically factorable.
A representation of pi bonding molecular orbitals of the conjugated enone, propenal, are delocalized through p-orbital overlap
The elimination of water from the reaction mixture can be used to drive the equilibrium towards the products by Le Chatelier’s principal. This coupled with the thermodynamic stability of the conjugated product allow for good reaction yields when the formation of the initial aldol intermediate is unfavorable (ketones & sterically hindered aldehydes).
Predicting the Product of an Enone Formation
Stereochemical Considerations
When aldehyde starting materials are used for an aldol condensation, there is the possibility of forming both E and Z alkene isomers. When symmetrical ketones are used, the alkene formed lacks the ability to form isomers so a single product is made.
Examples
Mechanism
Base Catalyzed Mechanism
1) Form an enolate
The mechanism starts with the base removing an alpha-hydrogen to form an enolate ion.
2) Form the enone
The alkoxide reforming the carbonyl C=O bond promotes the elimination of alcohol OH as a leaving group which reforms the base catalyst. Although the base catalyzed elimination of alcohols is rare, it happens in this case in part due to the stability of the conjugated enone product.
Acidic Conditions Mechanism
1) Protonation
The mechanism starts with the two step tautomerization process to form an enol.
2) Form an enol
3) Protonation
Protonation of the alcohol OH increases its ability to act as a leaving group.
4) Elimination
Lone pair electrons from the enol reform the carbonyl C=O bond and promoted the elimination of water as a leaving group.
5) Deprotonation
Deprotonation by water in the final step create the neutral enone product and regenerates the acid catalyst.
Aldol Condensation
Whether an aldol reaction or an aldol condensation product is formed during a reaction largely depends on the reaction conditions. Typically, a reaction with a base at room temperature provides the aldol reaction product. However, if the reaction mixture is heated the aldol product is quickly converted into the aldol condensation product. If the condensation product is desired the aldol intermediate is usually not isolated.
Examples
Aldol Reaction
Aldol Condensation
Worked Example
Draw the product of an aldol condensation with the following molecule:
- Answer
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The overall reaction is a combination of two major steps, an aldol reaction followed by a dehydration to form the enone. In this situation it is best to consider the aldol product first (as discussed in Section 23.3, then convert it to the enone. Note! The double bond always forms in conjugation with the carbonyl.


<IP_ADDRESS>: Meiosis Last updated Save as PDF Page ID 149564 Valeria Hochman Adler Reedley College Meiosis I Figure \(\PageIndex{1}\): Dividing pollen mother cell, Prophase I. In the first image, the cell is in the early stages of prophase with the chromatin still condensing (appears neon pink). In the second image, twelve replicated chromosomes are visible, stained a deep blue. There is no visible nuclear envelope or nucleolus. Photos by Doc. RNDr. Josef Reischig, CSc., CC BY-SA 3.0 , via Wikimedia Commons. Figure \(\PageIndex{2}\): Dividing pollen mother cell, Metaphase I. The chromosomes in these two cells (appearing neon pink) are lined up across the center of the cell where the new cell wall will form. Photo by Doc. RNDr. Josef Reischig, CSc., CC BY-SA 3.0 , via Wikimedia Commons. Figure \(\PageIndex{3}\): Dividing pollen mother cell, Metaphase I and Anaphase I. Here chromosomes are shown as stained bright pink. In the two cells on the left, the chromosomes are in the middle of the cell. The lower of these two cells is clearly in Metaphase I, with the chromosomes forming a distinct line across the cell. The cell on the right is in Anaphase I, sister chromatids (now each a chromosome) have been separated and pulled to either side. Photo by Doc. RNDr. Josef Reischig, CSc., CC BY-SA 3.0 , via Wikimedia Commons. Figure \(\PageIndex{4}\): Dividing pollen mother cells, Metaphase I and Telophase I. The cell on the top is in metaphase I, while the cell on the bottom is in telophase I. In the lower cell, there are two reforming nuclei. Distinct chromosomes are no longer distinguishable. Photo by Doc. RNDr. Josef Reischig, CSc., CC BY-SA 3.0 , via Wikimedia Commons. Meiosis II Figure \(\PageIndex{5}\): In the first image, cell A is clearly in prophase II. The white arrows point at the cell wall that formed during cytokinesis of meiosis I. There are two distinct nuclei with chromosomes condensing. Cells B and C are also in prophase II, but not clearly so (they appear to be in prophase I). This is because the second cell for each of these is under the first; the 3D nature of these structures makes it difficult to determine how many cells are present. In the second image, there are four dividing mother cells. The leftmost has four cells in it, while the other three have two. The three on the right are in prophase II, while the one on the left has completed meiosis. First photo by Maria Morrow, CC-BY 4.0 . Second photo by Doc. RNDr. Josef Reischig, CSc., CC BY-SA 3.0 , via Wikimedia Commons. Figure \(\PageIndex{6\): A pollen mother cell in Metaphase II. There is a clearly formed cell wall (indicated by white arrows), formed during meiosis I. The chromosomes are lined up in the center of each newly formed cell. Photo by Maria Morrow, CC-BY 4.0 . Figure \(\PageIndex{7}\): The three topmost cells are in telophase II, the lowest cell is in anaphase II. All four cells have a distinct cell wall. Photo by Doc. RNDr. Josef Reischig, CSc., CC BY-SA 3.0 , via Wikimedia Commons. Figure \(\PageIndex{8}\): Four pollen grains. Each of these pollen grains is haploid and genetically distinct. Photo by Doc. RNDr. Josef Reischig, CSc., CC BY-SA 3.0 , via Wikimedia Commons.


1.14.23: Enzyme-Substrate Interaction
We consider the formation in aqueous solution of an enzyme –substrate complex \(\mathrm{ES}\) by an enzyme \(\mathrm{E}\) and substrate \(\mathrm{S}\). The system is prepared using \(\mathrm{n}^{0} (\mathrm{E})\) moles of enzyme and \(\mathrm{n}^{0} (\mathrm{S}\)) moles of substrate; equation (a)
| \(\mathrm{E}(\mathrm{aq}) +\) | \(\mathrm{S}(\mathrm{aq}) \Leftrightarrow\) | \(\mathrm{ES}(\mathrm{aq})\) | |
| At \(t = 0\) | \(\mathrm{n}^{0}(\mathrm{E})\) | \(\mathrm{n}^{0}(\mathrm{S})\) | \(0 \mathrm{~mol}\) |
| At \(t = \infty\) | \(n^{0}(E)-\xi\) | \(\mathrm{n}^{0}(\mathrm{~S})-\xi\) | \(\xi \mathrm{~mol}\) |
The upper limit of the extent of interaction \(\xi\) is controlled by whichever is the smallest amount, either \(\mathrm{n}^{0}(\mathrm{E})\) or \(\mathrm{n}^{0}(\mathrm{S})\). The latter two variables determine the total amount of \(\mathrm{ES}(\mathrm{aq})\) which can be formed in the limit of tight binding.
The approach described above can be extended to more complicated schemes involving multip-step reactions. In the following we consider the case where enzyme \(\mathrm{E}\) converts substrate \(\mathrm{A}\) into product \(\mathrm{D}\). The system is prepared using \(\mathrm{n}^{0}(\mathrm{E})\) moles of enzyme and \(\mathrm{n}^{0}(\mathrm{A})\) moles of substrate \(\mathrm{A}\) such that there are two intermediates \(\mathrm{EB}(\mathrm{aq})\) and \(\mathrm{EC}(\mathrm{aq})\), product \(\mathrm{D}\) being liberated from the bound state in the final step. The equilibrium state can be represented by the following scheme.
\[\begin{aligned}
&\mathrm{E}(\mathrm{aq}) \quad+\mathrm{A}(\mathrm{aq}) \Leftrightarrow \mathrm{EB}(\mathrm{aq}) \Leftrightarrow \mathrm{EC}(\mathrm{aq}) \Leftrightarrow \mathrm{E}(\mathrm{aq})+\mathrm{D}(\mathrm{aq})\\
&\mathrm{n}^{0}(\mathrm{E})-\xi_{1}+\xi_{3} \mathrm{n}^{0}(\mathrm{~A})-\xi_{1} \quad \xi_{1}-\xi_{2} \quad \xi_{2}-\xi_{3} \quad \mathrm{n}^{0}(\mathrm{E})-\xi_{1}+\xi_{3} \xi_{3}
\end{aligned} \nonumber \]
The key point is that at equilibrium the amounts of enzyme \(\mathrm{E}(\mathrm{aq})\) identified at both ends of the reaction must be the same. Further a mass balance shows that the total amount of enzyme present equals \(\mathrm{n}^{0}(\mathrm{E}) \mathrm{~mol}\). Other features are interesting; \(\xi_{3}\) must be zero if \(\xi_{2}\) is zero. The method can be applied to more complicated reaction schemes including those where the path from reactant to product involves parallel reactions.


8.5: Efficient Decoding
We are now at the stage where we are able to generate linear codes that detect and correct errors fairly easily, but it is still a time-consuming process to decode a received \(n\)-tuple and determine which is the closest codeword, because the received \(n\)-tuple must be compared to each possible codeword to determine the proper decoding. This can be a serious impediment if the code is very large.
Given the binary matrix
and the \(5\)-tuples \({\mathbf x} = (11011)^{t}\) and \({\mathbf y} = (01011)^{t}\text{,}\)
Solution
we can compute
Hence, \({\mathbf x}\) is a codeword and \({\mathbf y}\) is not, since \({\mathbf x}\) is in the null space and \({\mathbf y}\) is not. Notice that \(H{\mathbf y}\) is identical to the first column of \(H\text{.}\) In fact, this is where the error occurred. If we flip the first bit in \({\mathbf y}\) from \(0\) to \(1\text{,}\) then we obtain \({\mathbf x}\text{.}\)
If \(H\) is an \(m \times n\) matrix and \({\mathbf x} \in {\mathbb Z}_2^n\text{,}\) then we say that the syndrome of \({\mathbf x}\) is \(H{\mathbf x}\text{.}\) The following proposition allows the quick detection and correction of errors.
Let the \(m \times n\) binary matrix \(H\) determine a linear code and let \({\mathbf x}\) be the received \(n\) -tuple. Write \({\mathbf x}\) as \({\mathbf x} = {\mathbf c} +{\mathbf e}\text{,}\) where \({\mathbf c}\) is the transmitted codeword and \({\mathbf e}\) is the transmission error. Then the syndrome \(H{\mathbf x}\) of the received codeword \({\mathbf x}\) is also the syndrome of the error \({\mathbf e}\text{.}\)
- Proof
-
The proof follows from the fact that
\[ H{\mathbf x} = H({\mathbf c} +{\mathbf e}) = H{\mathbf c} + H{\mathbf e} = {\mathbf 0} + H{\mathbf e} = H{\mathbf e}\text{.} \nonumber \]
This proposition tells us that the syndrome of a received word depends solely on the error and not on the transmitted codeword. The proof of the following theorem follows immediately from Proposition \(8.36\) and from the fact that \(H{\mathbf e}\) is the \(i\)th column of the matrix \(H\text{.}\)
Let \(H \in {\mathbb M}_{ m \times n} ( {\mathbb Z}_2)\) and suppose that the linear code corresponding to \(H\) is single error-correcting. Let \({\mathbf r}\) be a received \(n\) -tuple that was transmitted with at most one error. If the syndrome of \({\mathbf r}\) is \({\mathbf 0}\text{,}\) then no error has occurred; otherwise, if the syndrome of \({\mathbf r}\) is equal to some column of \(H\text{,}\) say the \(i\) th column, then the error has occurred in the \(i\) th bit
Consider the matrix
and suppose that the \(6\)-tuples \({\mathbf x} = (111110)^{t}\text{,}\) \({\mathbf y} = (111111)^{t}\text{,}\) and \({\mathbf z} = (010111)^{t}\) have been received.
Solution
Then
Hence, \({\mathbf x}\) has an error in the third bit and \({\mathbf z}\) has an error in the fourth bit. The transmitted codewords for \({\mathbf x}\) and \({\mathbf z}\) must have been \((110110)\) and \((010011)\text{,}\) respectively. The syndrome of \({\mathbf y}\) does not occur in any of the columns of the matrix \(H\text{,}\) so multiple errors must have occurred to produce \({\mathbf y}\text{.}\)
Coset Decoding
We can use group theory to obtain another way of decoding messages. A linear code \(C\) is a subgroup of \({\mathbb Z}_2^n\text{.}\) Coset or standard decoding uses the cosets of \(C\) in \({\mathbb Z}_2^n\) to implement maximum-likelihood decoding. Suppose that \(C\) is an \((n,m)\)-linear code. A coset of \(C\) in \({\mathbb Z}_2^n\) is written in the form \({\mathbf x} + C\text{,}\) where \({\mathbf x} \in {\mathbb Z}_2^n\text{.}\) By Lagrange's Theorem (Theorem \(6.10\)), there are \(2^{n-m}\) distinct cosets of \(C\) in \({\mathbb Z}_2^n\text{.}\)
Let \(C\) be the \((5,3)\)-linear code given by the parity-check matrix
Solution
The code consists of the codewords
There are \(2^{5-2} = 2^3\) cosets of \(C\) in \({\mathbb Z}_2^5\text{,}\) each with order \(2^2 =4\text{.}\) These cosets are listed in Table \(8.40\).
\(Table \text { } 8.40 .\) Cosets of \(C\)
| Coset | Coset |
| Representative | |
| \(C\) | \((00000) (01101) (10011) (11110)\) |
| \((10000) + C\) | \((10000) (11101) (00011) (01110)\) |
| \((01000) + C\) | \((01000) (00101) (11011) (10110)\) |
| \((00100) + C\) | \((00100) (01001) (10111) (11010)\) |
| \((00010) + C\) | \((00010) (01111) (10001) (11100)\) |
| \((00001) + C\) | \((00001) (01100) (10010) (11111)\) |
| \((10100) + C\) | \((00111) (01010) (10100) (11001)\) |
| \((00110) + C\) | \((00110) (01011) (10101) (11000)\) |
Our task is to find out how knowing the cosets might help us to decode a message. Suppose that \({\mathbf x}\) was the original codeword sent and that \({\mathbf r}\) is the \(n\)-tuple received. If \({\mathbf e}\) is the transmission error, then \({\mathbf r} = {\mathbf e} + {\mathbf x}\) or, equivalently, \({\mathbf x} = {\mathbf e} + {\mathbf r}\text{.}\) However, this is exactly the statement that \({\mathbf r}\) is an element in the coset \({\mathbf e} + C\text{.}\) In maximum-likelihood decoding we expect the error \({\mathbf e}\) to be as small as possible; that is, \({\mathbf e}\) will have the least weight. An \(n\)-tuple of least weight in a coset is called a coset leader . Once we have determined a coset leader for each coset, the decoding process becomes a task of calculating \({\mathbf r} + {\mathbf e}\) to obtain \({\mathbf x}\text{.}\)
In Table 8.40, notice that we have chosen a representative of the least possible weight for each coset.
Solution
These representatives are coset leaders. Now suppose that \({\mathbf r} = (01111)\) is the received word. To decode \({\mathbf r}\text{,}\) we find that it is in the coset \((00010) + C\text{;}\) hence, the originally transmitted codeword must have been \((01101) = (01111) + (00010)\text{.}\)
A potential problem with this method of decoding is that we might have to examine every coset for the received codeword. The following proposition gives a method of implementing coset decoding. It states that we can associate a syndrome with each coset; hence, we can make a table that designates a coset leader corresponding to each syndrome. Such a list is called a decoding table .
\(Table \text { } 8.42\). Syndromes for each coset
| Syndrome | Coset Leader |
| \((000)\) | \((00000)\) |
| \((001)\) | \((00001)\) |
| \((010)\) | \((00010)\) |
| \((011)\) | \((10000)\) |
| \((100)\) | \((00100)\) |
| \((101)\) | \((01000)\) |
| \((110)\) | \((00110)\) |
| \((111)\) | \((10100)\) |
Let \(C\) be an \((n,k)\) -linear code given by the matrix \(H\) and suppose that \({\mathbf x}\) and \({\mathbf y}\) are in \({\mathbb Z}_2^n\text{.}\) Then \({\mathbf x}\) and \({\mathbf y}\) are in the same coset of \(C\) if and only if \(H{\mathbf x} = H{\mathbf y}\text{.}\) That is, two \(n\) -tuples are in the same coset if and only if their syndromes are the same.
- Proof
-
Two \(n\)-tuples \({\mathbf x}\) and \({\mathbf y}\) are in the same coset of \(C\) exactly when \({\mathbf x} - {\mathbf y} \in C\text{;}\) however, this is equivalent to \(H({\mathbf x} - {\mathbf y}) = 0\) or \(H {\mathbf x} = H{\mathbf y}\text{.}\)
Table \(8.42\) is a decoding table for the code \(C\) given in Example \(8.39\). If \({\mathbf x} = (01111)\) is received,
Solution
then its syndrome can be computed to be
Examining the decoding table, we determine that the coset leader is \((00010)\text{.}\) It is now easy to decode the received codeword.
Given an \((n,k)\)-block code, the question arises of whether or not coset decoding is a manageable scheme. A decoding table requires a list of cosets and syndromes, one for each of the \(2^{n - k}\) cosets of \(C\text{.}\) Suppose that we have a \((32, 24)\)-block code. We have a huge number of codewords, \(2^{24}\text{,}\) yet there are only \(2^{32 - 24} = 2^{8} = 256\) cosets.


22.4: Gas Exchange
Learning Objectives
- Compare the composition of atmospheric air and alveolar air
- Describe the mechanisms that drive gas exchange
- Discuss the importance of sufficient ventilation and perfusion, and how the body adapts when they are insufficient
- Discuss the process of external respiration
- Describe the process of internal respiration
The purpose of the respiratory system is to perform gas exchange. Pulmonary ventilation provides air to the alveoli for this gas exchange process. At the respiratory membrane, where the alveolar and capillary walls meet, gases move across the membranes, with oxygen entering the bloodstream and carbon dioxide exiting. It is through this mechanism that blood is oxygenated and carbon dioxide, the waste product of cellular respiration, is removed from the body.
Gas Exchange
In order to understand the mechanisms of gas exchange in the lung, it is important to understand the underlying principles of gases and their behavior. In addition to Boyle’s law, several other gas laws help to describe the behavior of gases.
Gas Laws and Air Composition
Gas molecules exert force on the surfaces with which they are in contact; this force is called pressure. In natural systems, gases are normally present as a mixture of different types of molecules. For example, the atmosphere consists of oxygen, nitrogen, carbon dioxide, and other gaseous molecules, and this gaseous mixture exerts a certain pressure referred to as atmospheric pressure (Table \(\PageIndex{1}\)). Partial pressure ( P x ) is the pressure of a single type of gas in a mixture of gases. For example, in the atmosphere, oxygen exerts a partial pressure, and nitrogen exerts another partial pressure, independent of the partial pressure of oxygen (Figure \(\PageIndex{1}\)).
Total pressure is the sum of all the partial pressures of a gaseous mixture. Dalton’s law describes the behavior of nonreactive gases in a gaseous mixture and states that a specific gas type in a mixture exerts its own pressure; thus, the total pressure exerted by a mixture of gases is the sum of the partial pressures of the gases in the mixture.
| Gas | Percent of total composition |
Partial pressure (mm Hg) |
|---|---|---|
| Nitrogen (N 2 ) | 78.6 | 597.4 |
| Oxygen (O 2 ) | 20.9 | 158.8 |
| Water (H 2 O) | 0.04 | 3.0 |
| Carbon dioxide (CO 2 ) | 0.004 | 0.3 |
| Others | 0.0006 | 0.5 |
| Total composition/total atmospheric pressure | 100% | 760.0 |
Partial pressure is extremely important in predicting the movement of gases. Recall that gases tend to equalize their pressure in two regions that are connected. A gas will move from an area where its partial pressure is higher to an area where its partial pressure is lower. In addition, the greater the partial pressure difference between the two areas, the more rapid is the movement of gases.
Solubility of Gases in Liquids
Henry’s law describes the behavior of gases when they come into contact with a liquid, such as blood. Henry’s law states that the concentration of gas in a liquid is directly proportional to the solubility and partial pressure of that gas. The greater the partial pressure of the gas, the greater the number of gas molecules that will dissolve in the liquid. The concentration of the gas in a liquid is also dependent on the solubility of the gas in the liquid. For example, although nitrogen is present in the atmosphere, very little nitrogen dissolves into the blood, because the solubility of nitrogen in blood is very low. The exception to this occurs in scuba divers; the composition of the compressed air that divers breathe causes nitrogen to have a higher partial pressure than normal, causing it to dissolve in the blood in greater amounts than normal. Too much nitrogen in the bloodstream results in a serious condition that can be fatal if not corrected. Gas molecules establish an equilibrium between those molecules dissolved in liquid and those in air.
The composition of air in the atmosphere and in the alveoli differs. In both cases, the relative concentration of gases is nitrogen > oxygen > water vapor > carbon dioxide. The amount of water vapor present in alveolar air is greater than that in atmospheric air (Table \(\PageIndex{1}\)). Recall that the respiratory system works to humidify incoming air, thereby causing the air present in the alveoli to have a greater amount of water vapor than atmospheric air. In addition, alveolar air contains a greater amount of carbon dioxide and less oxygen than atmospheric air. This is no surprise, as gas exchange removes oxygen from and adds carbon dioxide to alveolar air. Both deep and forced breathing cause the alveolar air composition to be changed more rapidly than during quiet breathing. As a result, the partial pressures of oxygen and carbon dioxide change, affecting the diffusion process that moves these materials across the membrane. This will cause oxygen to enter and carbon dioxide to leave the blood more quickly.
| Gas | Percent of total composition |
Partial pressure (mm Hg) |
|---|---|---|
| Nitrogen (N 2 ) | 74.9 | 569 |
| Oxygen (O 2 ) | 13.7 | 104 |
| Water (H 2 O) | 6.2 | 40 |
| Carbon dioxide (CO 2 ) | 5.2 | 47 |
| Total composition/total alveolar pressure | 100% | 760.0 |
Ventilation and Perfusion
Two important aspects of gas exchange in the lung are ventilation and perfusion. Ventilation is the movement of air into and out of the lungs, and perfusion is the flow of blood in the pulmonary capillaries. For gas exchange to be efficient, the volumes involved in ventilation and perfusion should be compatible. However, factors such as regional gravity effects on blood, blocked alveolar ducts, or disease can cause ventilation and perfusion to be imbalanced.
The partial pressure of oxygen in alveolar air is about 104 mm Hg, whereas the partial pressure of the oxygenated pulmonary venous blood is about 100 mm Hg. When ventilation is sufficient, oxygen enters the alveoli at a high rate, and the partial pressure of oxygen in the alveoli remains high. In contrast, when ventilation is insufficient, the partial pressure of oxygen in the alveoli drops. Without the large difference in partial pressure between the alveoli and the blood, oxygen does not diffuse efficiently across the respiratory membrane. The body has mechanisms that counteract this problem. In cases when ventilation is not sufficient for an alveolus, the body redirects blood flow to alveoli that are receiving sufficient ventilation. This is achieved by constricting the pulmonary arterioles that serves the dysfunctional alveolus, which redirects blood to other alveoli that have sufficient ventilation. At the same time, the pulmonary arterioles that serve alveoli receiving sufficient ventilation vasodilate, which brings in greater blood flow. Factors such as carbon dioxide, oxygen, and pH levels can all serve as stimuli for adjusting blood flow in the capillary networks associated with the alveoli.
Ventilation is regulated by the diameter of the airways, whereas perfusion is regulated by the diameter of the blood vessels. The diameter of the bronchioles is sensitive to the partial pressure of carbon dioxide in the alveoli. A greater partial pressure of carbon dioxide in the alveoli causes the bronchioles to increase their diameter as will a decreased level of oxygen in the blood supply, allowing carbon dioxide to be exhaled from the body at a greater rate. As mentioned above, a greater partial pressure of oxygen in the alveoli causes the pulmonary arterioles to dilate, increasing blood flow.
Gas Exchange
Gas exchange occurs at two sites in the body: in the lungs, where oxygen is picked up and carbon dioxide is released at the respiratory membrane, and at the tissues, where oxygen is released and carbon dioxide is picked up. External respiration is the exchange of gases with the external environment, and occurs in the alveoli of the lungs. Internal respiration is the exchange of gases with the internal environment, and occurs in the tissues. The actual exchange of gases occurs due to simple diffusion. Energy is not required to move oxygen or carbon dioxide across membranes. Instead, these gases follow pressure gradients that allow them to diffuse. The anatomy of the lung maximizes the diffusion of gases: The respiratory membrane is highly permeable to gases; the respiratory and blood capillary membranes are very thin; and there is a large surface area throughout the lungs.
External Respiration
The pulmonary artery carries deoxygenated blood into the lungs from the heart, where it branches and eventually becomes the capillary network composed of pulmonary capillaries. These pulmonary capillaries create the respiratory membrane with the alveoli (Figure \(\PageIndex{2}\)). As the blood is pumped through this capillary network, gas exchange occurs. Although a small amount of the oxygen is able to dissolve directly into plasma from the alveoli, most of the oxygen is picked up by erythrocytes (red blood cells) and binds to a protein called hemoglobin, a process described later in this chapter. Oxygenated hemoglobin is red, causing the overall appearance of bright red oxygenated blood, which returns to the heart through the pulmonary veins. Carbon dioxide is released in the opposite direction of oxygen, from the blood to the alveoli. Some of the carbon dioxide is returned on hemoglobin, but can also be dissolved in plasma or is present as a converted form, also explained in greater detail later in this chapter.
External respiration occurs as a function of partial pressure differences in oxygen and carbon dioxide between the alveoli and the blood in the pulmonary capillaries.
Although the solubility of oxygen in blood is not high, there is a drastic difference in the partial pressure of oxygen in the alveoli versus in the blood of the pulmonary capillaries. This difference is about 64 mm Hg: The partial pressure of oxygen in the alveoli is about 104 mm Hg, whereas its partial pressure in the blood of the capillary is about 40 mm Hg. This large difference in partial pressure creates a very strong pressure gradient that causes oxygen to rapidly cross the respiratory membrane from the alveoli into the blood.
The partial pressure of carbon dioxide is also different between the alveolar air and the blood of the capillary. However, the partial pressure difference is less than that of oxygen, about 5 mm Hg. The partial pressure of carbon dioxide in the blood of the capillary is about 45 mm Hg, whereas its partial pressure in the alveoli is about 40 mm Hg. However, the solubility of carbon dioxide is much greater than that of oxygen—by a factor of about 20—in both blood and alveolar fluids. As a result, the relative concentrations of oxygen and carbon dioxide that diffuse across the respiratory membrane are similar.
Internal Respiration
Internal respiration is gas exchange that occurs at the level of body tissues (Figure \(\PageIndex{3}\)). Similar to external respiration, internal respiration also occurs as simple diffusion due to a partial pressure gradient. However, the partial pressure gradients are opposite of those present at the respiratory membrane. The partial pressure of oxygen in tissues is low, about 40 mm Hg, because oxygen is continuously used for cellular respiration. In contrast, the partial pressure of oxygen in the blood is about 100 mm Hg. This creates a pressure gradient that causes oxygen to dissociate from hemoglobin, diffuse out of the blood, cross the interstitial space, and enter the tissue. Hemoglobin that has little oxygen bound to it loses much of its brightness, so that blood returning to the heart is more burgundy in color.
Considering that cellular respiration continuously produces carbon dioxide, the partial pressure of carbon dioxide is lower in the blood than it is in the tissue, causing carbon dioxide to diffuse out of the tissue, cross the interstitial fluid, and enter the blood. It is then carried back to the lungs either bound to hemoglobin, dissolved in plasma, or in a converted form. By the time blood returns to the heart, the partial pressure of oxygen has returned to about 40 mm Hg, and the partial pressure of carbon dioxide has returned to about 45 mm Hg. The blood is then pumped back to the lungs to be oxygenated once again during external respiration.
Hyperbaric Chamber Treatment
A type of device used in some areas of medicine that exploits the behavior of gases is hyperbaric chamber treatment. A hyperbaric chamber is a unit that can be sealed and expose a patient to either 100 percent oxygen with increased pressure or a mixture of gases that includes a higher concentration of oxygen than normal atmospheric air, also at a higher partial pressure than the atmosphere. There are two major types of chambers: monoplace and multiplace. Monoplace chambers are typically for one patient, and the staff tending to the patient observes the patient from outside of the chamber (Figure \(\PageIndex{4}\)). Some facilities have special monoplace hyperbaric chambers that allow multiple patients to be treated at once, usually in a sitting or reclining position, to help ease feelings of isolation or claustrophobia. Multiplace chambers are large enough for multiple patients to be treated at one time, and the staff attending these patients is present inside the chamber. In a multiplace chamber, patients are often treated with air via a mask or hood, and the chamber is pressurized.
Chapter Review
The behavior of gases can be explained by the principles of Dalton’s law and Henry’s law, both of which describe aspects of gas exchange. Dalton’s law states that each specific gas in a mixture of gases exerts force (its partial pressure) independently of the other gases in the mixture. Henry’s law states that the amount of a specific gas that dissolves in a liquid is a function of its partial pressure. The greater the partial pressure of a gas, the more of that gas will dissolve in a liquid, as the gas moves toward equilibrium. Gas molecules move down a pressure gradient; in other words, gas moves from a region of high pressure to a region of low pressure. The partial pressure of oxygen is high in the alveoli and low in the blood of the pulmonary capillaries. As a result, oxygen diffuses across the respiratory membrane from the alveoli into the blood. In contrast, the partial pressure of carbon dioxide is high in the pulmonary capillaries and low in the alveoli. Therefore, carbon dioxide diffuses across the respiratory membrane from the blood into the alveoli. The amount of oxygen and carbon dioxide that diffuses across the respiratory membrane is similar.
Ventilation is the process that moves air into and out of the alveoli, and perfusion affects the flow of blood in the capillaries. Both are important in gas exchange, as ventilation must be sufficient to create a high partial pressure of oxygen in the alveoli. If ventilation is insufficient and the partial pressure of oxygen drops in the alveolar air, the capillary is constricted and blood flow is redirected to alveoli with sufficient ventilation. External respiration refers to gas exchange that occurs in the alveoli, whereas internal respiration refers to gas exchange that occurs in the tissue. Both are driven by partial pressure differences.
Review Questions
Q. Gas moves from an area of ________ partial pressure to an area of ________ partial pressure.
A. low; high
B. low; low
C. high; high
D. high; low
Answer: D
Q. When ventilation is not sufficient, which of the following occurs?
A. The capillary constricts.
B. The capillary dilates.
C. The partial pressure of oxygen in the affected alveolus increases.
D. The bronchioles dilate.
Answer: A
Q. Gas exchange that occurs at the level of the tissues is called ________.
A. external respiration
B. interpulmonary respiration
C. internal respiration
D. pulmonary ventilation
Answer: C
Q. The partial pressure of carbon dioxide is 45 mm Hg in the blood and 40 mm Hg in the alveoli. What happens to the carbon dioxide?
A. It diffuses into the blood.
B. It diffuses into the alveoli.
C. The gradient is too small for carbon dioxide to diffuse.
D. It decomposes into carbon and oxygen.
Answer: B
Critical Thinking Questions
Q. Compare and contrast Dalton’s law and Henry’s law.
A. Both Dalton’s and Henry’s laws describe the behavior of gases. Dalton’s law states that any gas in a mixture of gases exerts force as if it were not in a mixture. Henry’s law states that gas molecules dissolve in a liquid proportional to their partial pressure.
Q. A smoker develops damage to several alveoli that then can no longer function. How does this affect gas exchange?
A. The damaged alveoli will have insufficient ventilation, causing the partial pressure of oxygen in the alveoli to decrease. As a result, the pulmonary capillaries serving these alveoli will constrict, redirecting blood flow to other alveoli that are receiving sufficient ventilation.
Glossary
- Dalton’s law
- statement of the principle that a specific gas type in a mixture exerts its own pressure, as if that specific gas type was not part of a mixture of gases
- external respiration
- gas exchange that occurs in the alveoli
- Henry’s law
- statement of the principle that the concentration of gas in a liquid is directly proportional to the solubility and partial pressure of that gas
- internal respiration
- gas exchange that occurs at the level of body tissues
- partial pressure
- force exerted by each gas in a mixture of gases
- total pressure
- sum of all the partial pressures of a gaseous mixture
- ventilation
- movement of air into and out of the lungs; consists of inspiration and expiration


6.9: Pronombres de objeto indirecto y objeto directo usados juntos
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Objetivos
- Recognize and distinguish direct and indirect object pronouns when used together
- Use indirect and direct object pronouns in the correct position in a sentence
So far you’ve learned to identify direct and indirect objects in sentences like “Le compré unos recuerdos para mi papá.” ( I bought my father some souvenirs .) And you can use indirect and direct object pronouns separately, as in “Te mandé una tarjeta postal. ¿La recibiste?” ( I sent you a postcard. Did you receive it? )
When using indirect and direct object pronouns together in the same sentence, the indirect one goes first. The two pronouns must stay beside each other, and the usual object pronoun placement rules apply.
- ¿Los pasajes de avión? Nos los mandaron por correo electrónico. (The plane tickets? They sent them to us by email.)
- ¿Tu pasaporte? ¿No te lo devolví? ( Your passport? Didn’t I return it to you? )
- Mamá imprimió mi tarjeta de embarcación y ella va a dár mela al entrar en el puesto de seguridad. ( Mom printed my boarding pass and she is going to give me it when we go in the security checkpoint. )
Third-person object pronouns used together
An interesting thing happens when two third-person object pronouns are used together (e.g. “give it to them” or “receive them from her”): both the indirect and the direct object pronouns in the third person start with the letter “L”. For purely phonetic reasons (and not meaning to cause confusion with the reflexive pronoun!), the indirect object pronoun in those situations changes to “se”.
- ¿Los pasajes de avión para usted? Le Se los puse en este sobre. ( The plane tickets for you? I put them in this envelope for you .)
- Tu papá sabe todo sobre el vuelo, le se lo dije ayer. ( Your dad knows everything about the flight, I told (it to) him yesterday. )
- Aquí está tu visa para los oficiales de inmigración; necesitas presentárlesla presentár sela ahora. ( Here’s your visa for the immigration officers; you need to present it to them now. )
Where there’s likely to be confusion about who the “se” is referring to, be sure to use a prepositional phrase for clarification.


2.1: Introduction to Life Cycles
Green chemistry, in addition to being a science, it is also a philosophy and nearly a religion. Attendance at American Chemical Society Green Chemistry & Engineering Conferences will instill such an ideal into any attendant because of the universal appeal and possibilities in this novel approach to radicalizing the business of doing science and engineering. Life Cycle Assessment (LCA) is a comprehensive life cycle approach that quantifies ecological and human health impacts of a product or system over its complete life cycle. It uses credible scientific methods to model steady-state, global environmental and human health impacts. It also helps decision-makers understand the scale of many environmental and human health impacts of competing products, services, policies or actions.
Please see for more information https://www.youtube.com/watch?v=NQTW7jjXVmE (LCA: Intro to Life Cycle Assessment. (2013).)
Triple bottom line (economic, social, and environmental)
Triple Bottom Line accounting enables enterprises to support sustainability analysis in their operations, products and services. LCA contributes to the Triple Bottom Line reporting by quantifying the ecological and human health performance of competing products and services (Figure 2-1). Adding the social and economic performance reporting of a product or service to the LCA results of the product or service is one way to deliver Triple Bottom Line reporting.
LCA for Decision Making
Who makes decisions
- Company product managers or planners
- Company procurement and purchasing
- Industrial sector consortia (example: aluminum manufacturers)
- Regional or national policy makers
- Consumers, customers and product users
Primary drivers and expectations for LCA:
- Learning about the environmental performance of products and services
- Minimizing production and regulatory costs
- Minimizing environmental and human health damage
- Understanding trade-offs between multiple impact categories and product phases
- Supporting equitable economic distribution and profitable operations
Types of decision situations
- strategic planning and capital investments
- (green building, waste management)
- eco-design, product development
- operational management
- (green procurement)
- communication and marketing
- (eco-labeling, product information)
Eco-labels:
- Type 1: Third-party certified multi-criteria environmental labeling. Example: Forest Stewardship Council label for wood products
- Type 2: Environmental self-declaration claims. Example: Single issue claim such as the "bio-degradable" label
- Type 3: Independently verified label with preset quantified indices. Example: Numerical water consumption rating for a dish washer
Eco-labels that require LCA:
Type 1) Third-party certified multi-criteria environmental labeling
Type 3) Independently verified label with preset quantified indices
Life Cycle Assessment (LCA) enables the creation of Type 1 and Type 3 eco-labels. These eco-labels can be powerful tools in obtaining larger shares of a specific market sector. Life cycle assessment (LCA) is a standardized programmatic tool to determine the environmental impacts of products or services. It can be described by a four-part framework as outlined by the 14044 ISO standard.
- Goal and scope definition
- Life cycle inventory
- Life cycle impact assessment
- Interpretation
This integrated framework was inspired by earlier forms of life-cycle thought from life cycle financial analysis. Examining a product from origination to use and disposal provides more holistic analysis to identify where environmental impacts originate and guide efforts in reducing impacts.
The ISO standards ( http://www.iso.org/iso/home/standards.htm ) provides guidance on structure framework, reuse requirements of data, study assumptions, and methods. By using more standard LCA methodologies, studies are more comparable and of greater scientific rigor. A standardized method allows LCA practitioners to manage complex datasets, provide comparisons among products, and allow benchmarking. In the absence of a standardized method, the results of LCA studies are even more variable depending on study assumptions and methods. The ISO standards help reduce the influence of the practitioner influence on study results.


7.25J: Two-Hybrid Analysis
- Design a two-hybrid experiment
Understanding how proteins are physically connected reveals clues about their structure, function, and makes them an ideal target for drug therapy. Several methodologies exist to study the interaction of proteins in vivo. The most widely employed tools are the yeast two-hybrid system. The yeast two-hybrid screening system is an effective and quick tool for the in vivo study of protein–protein interaction both in prokaryotes and eukaryotes. The method consists of splitting a yeast transcription factor into its binding domain and activation domain, fusing the binding domain to one protein of interest (the bait) and the activation domain to another protein of interest (the prey), and reconstituting the activity of the transcription factor by bringing the two domains back into physical proximity. In the absence of an interaction the domains remain distant, preventing a detectable output. If the two proteins do interact the bait recruits the prey to a specific cellular location where it can stimulate a detectable output (e.g., gene activation). This experimental approach measures direct physical interaction between proteins and is called a binary method. Datasets obtained from such tools are further analyzed using computational methods to draw a map of protein connectivity and achieve system level understanding of a microorganism.
One limitation of classic yeast two-hybrid screens is that they are limited to soluble proteins. It is therefore impossible to use them to study the protein–protein interactions between insoluble integral membrane proteins. The split- ubiquitin system provides a method for overcoming this limitation. In the split-ubiquitin system, two integral membrane proteins to be studied are fused to two different ubiquitin moieties: a C-terminal ubiquitin moiety (“Cub”, residues 35–76) and an N-terminal ubiquitin moiety (“Nub”, residues 1–34). These fused proteins are called the bait and prey, respectively. In addition to being fused to an integral membrane protein, the Cub moiety is also fused to a transcription factor (TF) that can be cleaved off by ubiquitin specific proteases. Upon bait–prey interaction, Nub and Cub-moieties assemble, reconstituting the split-ubiquitin. The reconstituted split-ubiquitin molecule is recognized by ubiquitin specific proteases, which cleave off the reporter protein, allowing it to induce the transcription of reporter genes.
Summary
A key part of gene functional analysis and potential drug target discovery is an understanding of how proteins interact within the cell. Commercially available products facilitate the characterization of these interactions in yeast systems. The basic format involves the creation of two hybrid molecules, one in which a “bait” protein is fused with a transcription factor, and one in which a “prey” protein is fused with a related transcription factor. If the bait and prey proteins indeed interact, then the two factors fused to these two proteins are also brought into proximity with each other.
Key Terms
- computational : Of or relating to computation.
- ubiquitin : A small regulatory protein sequence that directs proteins to specific compartments within the cell. Specifically, a ubiquitin tag directs the protein to a proteasome, which destroys and recycles the components.
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Located at : en.Wikipedia.org/w/index.php?title=File:Simple_transcription_initiation1.svg&page=1 . License : CC BY-SA: Attribution-ShareAlike Courtney 2008. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Courtney_2008.jpg . License : CC BY-SA: Attribution-ShareAlike ChIP-on-chip wet-lab. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Ch...ip_wet-lab.png . License : CC BY-SA: Attribution-ShareAlike Two-hybrid analysis. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Two-hybrid_analysis . License : CC BY-SA: Attribution-ShareAlike computational. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/computational . License : CC BY-SA: Attribution-ShareAlike ubiquitin. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/ubiquitin . License : CC BY-SA: Attribution-ShareAlike SBTS4. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:SBTS4.png . License : CC BY-SA: Attribution-ShareAlike Inverse PCR. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Inverse_PCR.png . License : CC BY-SA: Attribution-ShareAlike Mu00e9ningo-encu00e9phalite amibienne primitive. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/File:M%C3%A9ningo-enc%C3%A9phalite_amibienne_primitive.JPG . License : Public Domain: No Known Copyright Northern Blot Scheme. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Northern_Blot_Scheme.PNG . License : CC BY-SA: Attribution-ShareAlike SDS-PAGE sample. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:SDS-PAGE_sample.png . License : CC BY-SA: Attribution-ShareAlike Gel shift assay. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Gel_shift_assay.png . License : CC BY-SA: Attribution-ShareAlike His-tag. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/His-tag . License : Public Domain: No Known Copyright File:Simple transcription initiation1.svg - Wikipedia, the free encyclopedia. Provided by : Wikipedia. Located at : http://en.Wikipedia.org/w/index.php?title=File:Simple_transcription_initiation1.svg&page=1 . License : CC BY-SA: Attribution-ShareAlike Courtney 2008. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Courtney_2008.jpg . License : CC BY-SA: Attribution-ShareAlike ChIP-on-chip wet-lab. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:ChIP-on-chip_wet-lab.png . License : CC BY-SA: Attribution-ShareAlike File:Two hybrid assay.svg - Wikipedia, the free encyclopedia. Provided by : Wikipedia. Located at : en.Wikipedia.org/w/index.php?...say.svg&page=1 . License : CC BY-SA: Attribution-ShareAlike