22.2: Overview of the Kidney
By the end of the section, you will be able to:
- Describe the external structure of the kidney, including its location, support structures, and covering
- Identify the major internal divisions and structures of the kidney
- Identify the major blood vessels associated with the kidney and trace the path of blood through the kidney
- Name the structures in a nephron
- Trace the flow of fluid from blood through the kidney as urine
The kidneys lie on either side of the spine in the retroperitoneal space between the parietal peritoneum and the posterior abdominal wall, well protected by muscle, fat, and ribs. They are roughly the size of your fist, and the male kidney is typically a bit larger than the female kidney. The kidneys are well vascularized, receiving about 25 percent of the cardiac output at rest.
Interactive Link
There have never been sufficient kidney donations to provide a kidney to each person needing one. Watch this video Printing A Human Kidney to learn about the TED (Technology, Entertainment, Design) Conference held in March 2011. In this video, Dr. Anthony Atala discusses a cutting-edge technique in which a new kidney is “printed.” The successful utilization of this technology is still several years in the future, but imagine a time when you can print a replacement organ or tissue on demand.
External Anatomy
The left kidney is located at about the T12 to L3 vertebrae, whereas the right is lower due to slight displacement by the liver. Upper portions of the kidneys are somewhat protected by the eleventh and twelfth ribs (Figure 22.2.1). The two lowest ribs, which are also floating ribs, are hovering over the two kidneys. Each kidney weighs about 125–175 g in males and 115–155 g in females. They are about 11–14 cm in length, 6 cm wide, and 4 cm thick, and are directly covered by a fibrous capsule composed of dense, irregular connective tissue that helps to hold their shape and protect them. This capsule is covered by a shock-absorbing layer of adipose tissue called the renal fat pad , which in turn is encompassed by a tough renal fascia . The fascia and, to a lesser extent, the overlying peritoneum serve to firmly anchor the kidneys to the posterior abdominal wall in a retroperitoneal position.
On the superior aspect of each kidney is the adrenal gland. The adrenal cortex directly influences renal function through the production of the hormone aldosterone to stimulate sodium reabsorption.
Renal Hilum
The renal hilum is the entry and exit site for structures servicing the kidneys: vessels, nerves, lymphatics, and ureters . The medial-facing hila are tucked into the sweeping convex outline of the cortex. Emerging from the hilum is the renal pelvis , which is formed from the major and minor calyces (calyx singular) in the kidney. The smooth muscle in the renal pelvis funnels urine via peristalsis into the ureter. The renal arteries form directly from the descending aorta, whereas the renal veins return cleansed blood directly to the inferior vena cava. The artery, vein, and renal pelvis are arranged in an anterior-to-posterior order.
Internal Anatomy
A frontal section through the kidney reveals a thin outer region called the renal cortex and an inner region called the medulla (Figure 22.2.2). The renal columns are connective tissue extensions that radiate downward from the cortex through the medulla to separate the most characteristic features of the medulla: the renal pyramids and renal papillae . The papillae are bundles of collecting ducts that transport urine made by nephrons, explained further down, to the minor calyces then the major calyces of the kidney then to the renal pelvis for excretion. The renal columns also serve to divide the kidney into 6–8 lobes and provide a supportive framework for vessels that enter and exit the cortex. The pyramids and renal columns taken together constitute the kidney lobes.
Blood Vessels
The renal artery enters the kidney medially, first divides into segmental arteries moving toward the medulla, followed by further branching to form interlobar arteries that pass through the renal columns to reach the cortex (Figure 22.2.3). The interlobar arteries, in turn, branch into arcuate arteries lying between the renal cortex and renal medulla. Arcuate arteries will branch further to form interlobular or cortical radiate arteries that extends into the cortex, and then branch into afferent arterioles . The afferent arterioles service about 1.3 million nephrons in each kidney. Afferent arterioles lead blood to the beginning of the nephron.
Nephrons are the “functional units” of the kidney; they cleanse the blood and balance the constituents of the circulation. (Figures 22.2.5 and 22.2.6) The afferent arterioles form a tuft of high-pressure capillaries about 200 µm in diameter, called the glomerulus . The rest of the nephron consists of a continuous sophisticated tubule whose proximal end surrounds the glomerulus in an intimate embrace—this is Bowman’s capsule (glomerular capsule) . The glomerulus and Bowman’s capsule together form the renal corpuscle . These glomerular capillaries filter the blood based on particle size. After passing through the renal corpuscle, the capillaries form a second arteriole, the efferent arteriole . These will next form a capillary network around the more distal portions of the nephron tubule, the peritubular capillaries (around the tubules) and vasa recta (straight vessels) that will run around the nephron loop , before returning to the venous system. Blood from the capillaries then empty into venules. These merge to form interlobular veins , which then merge to form arcuate veins . These then merge to form interlobar veins which merge to become the renal vein . (Figure 22.2.3) There is no segmental vein. As the glomerular filtrate progresses through the nephron, these capillary networks recover most of the solutes and water, and return them to the circulation.
Since a capillary bed (the glomerulus) drains into a vessel that in turn forms a second capillary bed, the definition of a portal system is met. This is the only portal system in which an arteriole is found between the first and second capillary beds. (Portal systems also link the hypothalamus to the anterior pituitary, and the blood vessels of the digestive viscera to the liver.)
Nephrons
Nephrons are microscopic structures to make urine, thus they are the "functional" units in the kidneys. Figures 22.2.4 shows one nephron and the blood vessels running around it. Each nephron starts with the renal corpuscle , which has the Bowman's capsule surrounding the glomerulus (capillary). The renal corpuscle continues as the proximal convoluted tubule (PCT) which straightens out as the descending limb and makes a U-turn to become the ascending limb of the nephron loop. Nephron loop is also called the loop of Henle . The loop will become the distal convoluted tubule (DCT) and this is the end of the nephron. The content inside, soon to be urine, will continue from the DCT to the collecting duct.
In a dissected kidney, it is easy to identify the cortex; it appears lighter in color compared to the rest of the kidney. Different parts of the nephrons are found in the cortex. All of the renal corpuscles as well as both the proximal convoluted tubules (PCTs) and distal convoluted tubules are found here. Some nephrons have a short loop of Henle that does not dip beyond the cortex. These nephrons are called cortical nephrons . About 15 percent of nephrons have long loops of Henle that extend deep into the medulla and are called juxtamedullary nephrons . Figure 22.2.5 shows two types of nephrons, cortical and juxtamedullary nephrons, named according to their locations. Details of nephrons will be discussed in the next section, Section 22.3.
Concept Review
As noted previously, the structure of the kidney is divided into two principle regions—the peripheral rim of cortex and the central medulla. The two kidneys receive about 25 percent of cardiac output. They are protected in the retroperitoneal space by the renal fat pad and overlying ribs and muscle. Ureters, blood vessels, lymph vessels, and nerves enter and leave at the renal hilum. The renal arteries arise directly from the aorta, and the renal veins drain directly into the inferior vena cava. Kidney function is derived from the actions of about 1.3 million nephrons per kidney; these are the “functional units.” A capillary bed, the glomerulus, filters blood and the filtrate is captured by Bowman’s capsule. A portal system is formed when the blood flows through a second capillary bed surrounding the proximal and distal convoluted tubules and the loop of Henle. Most water and solutes are recovered by this second capillary bed. This filtrate is processed and finally gathered by collecting ducts that drain into the minor calyces, which merge to form major calyces; the filtrate then proceeds to the renal pelvis and finally the ureters.
Review Questions
Q. The renal pyramids are separated from each other by extensions of the renal cortex called ________.
A. renal medulla
B. minor calyces
C. medullary cortices
D. renal columns
- Answer
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Answer: D
Q. The primary structure found within the medulla is the ________.
A. loop of Henle
B. minor calyces
C. portal system
D. ureter
- Answer
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Answer: A
Q. The right kidney is slightly lower because ________.
A. it is displaced by the liver
B. it is displace by the heart
C. it is slightly smaller
D. it needs protection of the lower ribs
- Answer
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Answer: A
Q. What are the names of the capillaries following the efferent arteriole?
A. arcuate and medullary
B. interlobar and interlobular
C. peritubular and vasa recta
D. peritubular and medullary
Answer
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Answer: C
Critical Thinking Questions
Q. What anatomical structures provide protection to the kidney?
- Answer
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A. Retroperitoneal anchoring, renal fat pads, and ribs provide protection to the kidney.
Q. How does the renal portal system differ from the hypothalamo–hypophyseal and digestive portal systems?
- Answer
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A. The renal portal system has an artery between the first and second capillary bed. The others have a vein.
Glossary
- Bowman’s capsule
- cup-shaped sack lined by a simple squamous epithelium (parietal surface) and specialized cells called podocytes (visceral surface) that participate in the filtration process; receives the filtrate which then passes on to the PCTs
- calyces
- cup-like structures receiving urine from the collecting ducts where it passes on to the renal pelvis and ureter
- cortical nephrons
- nephrons with loops of Henle that do not extend into the renal medulla
- distal convoluted tubules
- portions of the nephron distal to the loop of Henle that receive hyposmotic filtrate from the loop of Henle and empty into collecting ducts
- efferent arteriole
- arteriole carrying blood from the glomerulus to the capillary beds around the convoluted tubules and loop of Henle; portion of the portal system
- glomerulus
- tuft of capillaries surrounded by Bowman’s capsule; filters the blood based on size
- juxtamedullary nephrons
- nephrons adjacent to the border of the cortex and medulla with loops of Henle that extend into the renal medulla
- loop of Henle
- descending and ascending portions between the proximal and distal convoluted tubules; those of cortical nephrons do not extend into the medulla, whereas those of juxtamedullary nephrons do extend into the medulla
- nephrons
- functional units of the kidney that carry out all filtration and modification to produce urine; consist of renal corpuscles, proximal and distal convoluted tubules, and descending and ascending loops of Henle; drain into collecting ducts
- medulla
- inner region of kidney containing the renal pyramids
- peritubular capillaries
- second capillary bed of the renal portal system; surround the proximal and distal convoluted tubules; associated with the vasa recta
- proximal convoluted tubules (PCTs)
- tortuous tubules receiving filtrate from Bowman’s capsule; most active part of the nephron in reabsorption and secretion
- renal columns
- extensions of the renal cortex into the renal medulla; separates the renal pyramids; contains blood vessels and connective tissues
- renal corpuscle
- consists of the glomerulus and Bowman’s capsule
- renal cortex
- outer part of kidney containing all of the nephrons; some nephrons have loops of Henle extending into the medulla
- renal fat pad
- adipose tissue between the renal fascia and the renal capsule that provides protective cushioning to the kidney
- renal hilum
- recessed medial area of the kidney through which the renal artery, renal vein, ureters, lymphatics, and nerves pass
- renal papillae
- medullary area of the renal pyramids where collecting ducts empty urine into the minor calyces
- renal pyramids
- six to eight cone-shaped tissues in the medulla of the kidney containing collecting ducts and the loops of Henle of juxtamedullary nephrons
- vasa recta
- branches of the efferent arterioles that parallel the course of the loops of Henle and are continuous with the peritubular capillaries; with the glomerulus, form a portal system
Contributors and Attributions
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OpenStax Anatomy & Physiology (CC BY 4.0). Access for free at https://openstax.org/books/anatomy-and-physiology


5.4: Why It Matters- Managerial Accounting in Business
Why learn about managerial accounting?
There are many differences between financial accounting and managerial accounting. Financial accounting is a requirement, in order to have the information available to prepare tax returns, and financial statements. Outside investors, banks and regulatory agencies need historical information to provide funding and to impose taxes.
Managerial accounting on the other hand is not a regulatory requirement, but it is a requirement for a business to plan and make good decisions. Without managerial accounting, it may be difficult for a business to show a profit, create effective pricing and cost models and overall, be a business that can last.


15.6A: Overview of Endocrine Glands
Endocrine glands are glands that have no duct and release their secretions directly into the intercellular fluid or into the blood.
- Differentiate among the types of endocrine glands (pituitary [posterior pituitary, anterior pituitary], thyroid, parathyroid, adrenal, and pancreas) in the endocrine system
Key Points
- The main endocrine glands are the pituitary (anterior and posterior lobes), thyroid, parathyroid, adrenal (cortex and medulla), pancreas, and gonads.
- The parathyroid glands are four masses of tissue, two embedded posteriorly in each lateral mass of the thyroid gland.
- The pancreas lies along the lower curvature of the stomach, close to where it meets the first region of the small intestine, the duodenum.
Key Terms
- adrenal gland : This gland is responsible for releasing hormones in response to stress through the synthesis of corticosteroids, such as cortisol and catecholamines (epinephrine (adrenaline) and norepinephrine), as well as the production of androgens.
- thyroid : One of the largest endocrine glands, it is responsible for the secretion of thyroxine which controls how quickly the body uses energy, makes proteins, and is sensitive to other hormones.
Endocrine glands are ductless and release their secretions directly into the intercellular fluid or into the blood. A collection of endocrine glands makes up the endocrine system: the pituitary (anterior and posterior lobes), thyroid, parathyroid, adrenal (cortex and medulla), pancreas and gonads.
Endocrine glands in the human head and neck : The endocrine system is the system of glands, each of which secretes different types of hormones directly into the bloodstream (some of which are transported along nerve tracts) to regulate the body.
Pituitary Gland
The hypothalamus makes up the lower region of the diencephalons and lies just above the brain stem. The pituitary gland (hypophysis) is found in the inferior part of the brain, attached to the bottom of the hypothalamus by a slender stalk called the infundibulum.
The pituitary gland consists of two major regions, the anterior pituitary gland (adenohypophysis) and the posterior pituitary gland (neurohypophysis). The hypothalamus also controls the glandular secretion of the pituitary gland.
Posterior Pituitary Gland
Communication between the hypothalamus and the posterior pituitary occurs through neurosecretory cells that span the short distance between them. Hormones produced by the cell bodies of the neurosecretory cells are packaged in vesicles and transported through the axon and stored in the axon terminals that lie in the posterior pituitary.
When the neurosecretory cells are stimulated, the action potential generated triggers the release of the stored hormones from the axon terminals to a capillary network within the posterior pituitary. Two hormones—oxytocin and antidiuretic hormone (ADH)—are produced and released this way.
Anterior Pituitary Gland
The anterior pituitary is involved in sending hormones that control all other hormones of the body. Its lobe is derived from oral ectoderm and is composed of glandular epithelium.
Communication between the hypothalamus and the anterior pituitary occurs through hormones (releasing hormones and inhibiting hormones) that are produced by the hypothalamus and delivered to the anterior pituitary via a portal network of capillaries. The releasing and inhibiting hormones are produced by specialized neurons of the hypothalamus called neurosecretory cells.
These hormones are released into a capillary network that supplies the anterior pituitary. The hormones then diffuse from this secondary plexus into the anterior pituitary, where they initiate the production of specific hormones by the anterior pituitary.
Thyroid Gland
This is one of the largest endocrine glands in the body. It is positioned on the neck just below the larynx and has two lobes, one on either side of the trachea.
It is involved in the production of the hormones T3 (triiodothyronine) and T4 (thyroxine). These hormones increase the metabolic activity of the body‘s cells.
The thyroid also produces and releases the hormone calcitonin (thyrocalcitonin) that contributes to the regulation of blood calcium levels. Thyrocalcitonin or calcitonin decreases the concentration of calcium in the blood, where most of it is stored in the bones.
Parathyroid
There are four parathyroid glands, all located on the thyroid gland. One of its most important functions is to regulate the body’s calcium and phosphorus levels.
All four glands also secrete parathyroid hormone, or PTH, which causes calcium to be released from the bones back into the extracellular fluid. PTH is released directly into the bloodstream and travels to its target cells, which are often quite far away and found in bone, kidneys, and the gastrointestinal system.
Calcitonin, a hormone produced by the thyroid gland that also regulates ECF calcium levels, serves to counteract the calcium-producing effects of PTH.
Adrenal Glands
Adrenal glands : These are responsible for releasing hormones in response to stress through the synthesis of corticosteroids such as cortisol, and catecholamines such as epinephrine (adrenaline) and norepinephrine.
The adrenal glands are a pair of ductless glands located above the kidneys. Through hormonal secretions, they regulate many essential bodily functions including biochemical balances that influence athletic training and general stress response.
The glucocorticoids include corticosterone, cortisone, and hydrocortisone or cortisol. These hormones serve to stimulate the conversion of amino acids into carbohydrates, a process known as gluconeogenesis, and the formation of glycogen by the liver. They also stimulate the formation of reserve glycogen in the tissues, such as in the muscles.
Pancreas
The pancreas is a very important organ in the digestive and the circulatory systems that helps to maintain our blood sugar levels. It is considered to be part of the gastrointestinal system since it produces digestive enzymes. These are released into the small intestine to aid in reducing food particles to basic elements that can be absorbed by the intestine and used by the body.
It has another, very different function in that it forms insulin, glucagon, and other hormones that are sent into the bloodstream to regulate blood sugar levels and other activities throughout the body.
LICENSES AND ATTRIBUTIONS
CC LICENSED CONTENT, SHARED PREVIOUSLY
- Curation and Revision. Authored by : Boundless.com. Provided by : Boundless.com. License : CC BY-SA: Attribution-ShareAlike
CC LICENSED CONTENT, SPECIFIC ATTRIBUTION
- thyroid. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/thyroid . License : CC BY-SA: Attribution-ShareAlike
- Human Physiology/The endocrine system. Provided by : Wikibooks. Located at : en.wikibooks.org/wiki/Human_Physiology/The_endocrine_system%23Endocrine_Glands . License : CC BY-SA: Attribution-ShareAlike
- hormone. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/hormone . License : CC BY-SA: Attribution-ShareAlike
- adrenal gland. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/adrenal%20gland . License : CC BY-SA: Attribution-ShareAlike
- Endocrine central nervous en. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Endocrine_central_nervous_en.svg . License : CC BY-SA: Attribution-ShareAlike
- Adrenal gland. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Adrenal_gland . License : Public Domain: No Known Copyright


1: Introduction to Child Development
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Learning Objectives
After this chapter, you should be able to:
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Describe the principles that underlie development.
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Differentiate periods of human development.
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Evaluate issues in development.
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Distinguish the different methods of research.
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Explain what a theory is.
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Compare and contrast different theories of child development.
Welcome to Child Growth and Development. This text is a presentation of how and why children grow, develop, and learn. We will look at how we change physically over time from conception through adolescence. We examine cognitive change, or how our ability to think and remember changes over the first 20 years or so of life. And we will look at how our emotions, psychological state, and social relationships change throughout childhood and adolescence. As we begin the study of a child's growth and development, we first need to understand that children have rights. Below are some of the organizations that discuss and share exactly what those rights are.
Children Have Rights
According to the National Association for the Education of Young Children (Code of Ethical Conduct and Statement of Commitment), states that our primary responsibility to children is "above all, we shall not harm children (1.1). We shall not participate in practices that are emotionally damaging, physically harmful, disrespectful, degrading, dangerous, exploitative, or intimidating to children. This principle has precedence over all others" (NAEYC, 2011). 1
Marian Wright Edelman
Marian Wright Edelman founded the Children Defense Fund in 1973. She has been the strongest voice for children and families to ensure that every child gets a healthy head start, a fair start, a safe start and a moral start in life as they move into adulthood with the help of families and communities. She recognized children's rights and racial equity, and has been an advocate in pursuing policies that reduce the impact of poverty on children protecting them from abuse and neglect, and providing children with educational opportunities. The CDF works on federal legislation to make sure every child in America has everything they need to thrive, fixing systemic inequities, specifically focusing on poor children, children of color and those with disabilities. 2
"We would like to create a world familiar with the smiles of children rather than their tears"
- Nelson Mandela


1.7: Ion Selective Electrode Analysis
Introduction
Ion selective electrode (ISE) is an analytical technique used to determine the activity of ions in aqueous solution by measuring the electrical potential. ISE has many advantages compared to other techniques, including:
- It is relatively inexpensive and easy to operate.
- It has wide concentration measurement range.
- As it measure the activity, instead of concentration, it is particularly useful in biological/medical application.
- It is a real-time measurement, which means it can monitor the change of activity of ion with time.
- It can determine both positively and negatively charged ions.
Based on these advantages, ISE has wide variety of applications, which is reasonable considering the importance of measuring ion activity. For example, ISE finds its use in pollution monitoring in natural waters (CN - , F - , S - , Cl - , etc.), food processing (NO 3 - , NO 2 - in meat preservatives), Ca 2+ in dairy products, and K + in fruit juices, etc.
Measurement setup
Before focusing on how ISE works, it would be good to get an idea what ISE setup looks like and the component of the ISE instrument. Figure \(\PageIndex{1}\) shows the basic components of ISE setup. It has an ion selective electrode, which allows measured ions to pass, but excludes the passage of the other ions. Within this ion selective electrode, there is an internal reference electrode, which is made of silver wire coated with solid silver chloride, embedded in concentrated potassium chloride solution (filling solution) saturated with silver chloride. This solution also contains the same ions as that to be measured. There is also a reference electrode similar to ion selective electrode, but there is no to-be-measured ion in the internal electrolyte and the selective membrane is replaced by porous frit, which allows the slow passage of the internal filling solution and forms the liquid junction with the external text solution. The ion selective electrode and reference electrode are connected by a milli-voltmeter. Measurment is accomplished simply by immersing the two electrodes in the same test solution.
Theory of How ISE Works
There are commonly more than one types of ions in solution. So how ISE manage to measure the concentration of certain ion in solution without being affected by other ions? This is done by applying a selective membrane at the ion selective electrode, which only allows the desired ion to go in and out. At equilibrium, there is potential difference existing between two sides of the membrane, and it is governed by the concentration of the tested solution described by Nernst equation EQ, where E is potential, E 0 is a constant characteristic of a particular ISE, R is the gas constant (8.314 J/K.mol), T is the temperature (in K), n is the charge of the ion and F is Faraday constant (96,500 coulombs/mol). To make it relevant, the measured potential difference is proportional to the logarithm of ion concentration. Thus, the relationship between potential difference and ion concentration can be determined by measuring the potential of two solutions of already-known ion concentration and a plot based on the measured potential and logarithm of the ion concentration. Based on this plot, the ion concentration of an unknown solution can be known by measuring the potential and corresponding it to the plot.
\[ E = E ^ { 0 } + ( 2.030~RT / nF ) \log C \label{eq:nernst} \]
Example Application: Determination of Fluoride Ion
Fluoride is added into drinking water and toothpaste to prevent dental caries and thus the determination of its concentration is of great importance to human health. Here, we will give some data and calculations to show how the concentration of fluoride ion is determined and have a glance at how relevant ISE is to our daily life. According to Nernst equation, (Equation \ref{eq:nernst}), in this case n = 1, T = 25 °C and E 0 , R, F are constants and thus this equation can be simplied as
\[ E= K+S\log C \nonumber \]
The first step is to obtain a calibration curve for fluoride ion and this can be done by preparing several fluoride standard solution with known concentration and making a plot of E versus log C.
| Concentration (mg/L) | log C | E (mV) |
| 200.0 | 2.301 | -35.6 |
| 100.0 | 2.000 | -17.8 |
| 50.00 | 1.699 | 0.4 |
| 25.00 | 1.398 | 16.8 |
| 12.50 | 1.097 | 34.9 |
| 6.250 | 0.796 | 52.8 |
| 3.125 | 0.495 | 70.4 |
| 1.563 | 0.194 | 89.3 |
| 0.781 | 0.107 | 107.1 |
| 0.391 | 0.408 | 125.5 |
| 0.195 | 0.709 | 142.9 |
From the plot we can clearly identify the linear relationship between E versus log C with slope measured at -59.4 mV, which is very closed to the theoretical value -59.2 mV at 25 °C. This plot can give the concentration of any solution containing fluoride ion within the range of 0.195 mg/L and 200 mg/L by measuring the potential of the unknown solution.
Limit of ISE
Though ISE is a cost-effective and useful technique, it has some drawbacks that cannot be avoided. The selective ion membrane only allows the measured ions to pass and thus the potential is only determined by this particular ion. However, the truth is there is no such membrane that only permits the passage of one ion, and so there are cases when there are more than one ions that can pass the membrane. As a result, the measured potential are affected by the passage of the “unwanted” ions. Also, because of its dependence on ion selective membrane, one ISE is only suitable for one ion and this may be inconvenient sometimes. Another problem worth noticing is that ion selective measures the concentration of ions in equilibrium at the surface of the membrane surface. This does matter much if the solution is dilute but at higher concentrations, the inter-ionic interactions between the ions in the solution tend to decrease the mobility of ions and thus the concentration near the membrane would be lower than that in the bulk. This is one source of inaccuracy of ISE. To better analyze the results of ISE, we have to be aware of these inherent limitations of it.
Bibliography
- D. S. Papastathopoulos and M. I. Karayannis, J. Chem. Edu. , 1980, 57 , 904.
- J. E. O'Reilly, J. Chem. Edu. , 1979, 56 , 279.
- F. Scholz, Electroanalytical Methods: Guide to Experiments and Application , 2 nd edition, Springer, Berlin (2010).
- R. Greef, R. Peat, L. M. Peter, D. Pletcher, and J. Robinson, Instrumental Methods in Electrochemistry , Ellis Horwood, Chichester (1985).


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Chapter 18: The Cardiovascular System - Blood
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Chapter Objectives
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Identify the primary functions of blood, its fluid and cellular components, and its physical characteristics
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Identify the most important proteins and other solutes present in blood plasma
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Describe the formation of the formed element components of blood
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Discuss the structure and function of red blood cells and hemoglobin
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Classify and characterize white blood cells
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Describe the structure of platelets and explain the process of hemostasis
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Explain the significance of AB and Rh blood groups in blood transfusions
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Discuss a variety of blood disorders
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18.1: Introduction
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Single-celled organisms do not need blood. They obtain nutrients directly from and excrete wastes directly into their environment. The human organism cannot do that. Our large, complex bodies need blood to deliver nutrients to and remove wastes from our trillions of cells. The heart pumps blood throughout the body in a network of blood vessels.  The cellular elements—referred to as the formed elements—include red blood cells, white blood cells, and cell fragments called platelets. The extracellular matrix, called plasma, makes blood unique among connective tissues because it is fluid. This fluid, which is mostly water, perpetually suspends the formed elements and enables them to circulate throughout the body within the cardiovascular system.
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18.3: Production of the Formed Elements
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Although one type of leukocyte called memory cells can survive for years, most erythrocytes, leukocytes, and platelets normally live only a few hours to a few weeks. Thus, the body must form new blood cells and platelets quickly and continuously. Your body typically replaces the donated plasma within 24 hours and it takes about 4 to 6 weeks to replace the blood cells. The process by which this replacement occurs is called hemopoiesis, or hematopoiesis.
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18.4: Erythrocytes
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The erythrocyte, commonly known as a red blood cell (or RBC), is by far the most common formed element: A single drop of blood contains millions of erythrocytes and just thousands of leukocytes. Specifically, males have about 5.4 million erythrocytes per microliter (µL) of blood, and females have approximately 4.8 million per µL. In fact, erythrocytes are estimated to make up about 25 percent of the total cells in the body.
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18.5: Leukocytes and Platelets
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The leukocyte, commonly known as a white blood cell (or WBC), is a major component of the body’s defenses against disease. Leukocytes protect the body against invading microorganisms and body cells with mutated DNA, and they clean up debris. Platelets are essential for the repair of blood vessels when damage to them has occurred; they also provide growth factors for healing and repair.
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18.6: Hemostasis
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Platelets are key players in hemostasis, the process by which the body seals a ruptured blood vessel and prevents further loss of blood. Although rupture of larger vessels usually requires medical intervention, hemostasis is quite effective in dealing with small, simple wounds. There are three steps to the process: vascular spasm, the formation of a platelet plug, and coagulation (blood clotting). Failure of any of these steps will result in hemorrhage—excessive bleeding.
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18.7: Blood Typing
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Blood transfusions in humans were risky procedures until the discovery of the major human blood groups by Karl Landsteiner, an Austrian biologist and physician, in 1900. Until that point, physicians did not understand that death sometimes followed blood transfusions, when the type of donor blood infused into the patient was incompatible with the patient’s own blood. Blood groups are determined by the presence or absence of specific marker molecules on the plasma membranes of erythrocytes.
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18.8: Key Terms
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18.9: Chapter Review
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18.10: Interactive Link Questions
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18.11: Review Questions
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18.12: Critical Thinking Questions
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1.4: What is a Tectonic Plate?
A tectonic plate (also called lithospheric plate) is a massive, irregularly shaped slab of solid rock, generally composed of both continental and oceanic lithosphere. Plate size can vary greatly, from a few hundred to thousands of kilometers across; the Pacific and Antarctic Plates are among the largest. Plate thickness also varies greatly, ranging from less than 15 km for young oceanic lithosphere to about 200 km or more for ancient continental lithosphere (for example, the interior parts of North and South America).
How do these massive slabs of solid rock float despite their tremendous weight? The answer lies in the composition of the rocks. Continental crust is composed of granitic rocks which are made up of relatively lightweight minerals such as quartz and feldspar. By contrast, oceanic crust is composed of basaltic rocks, which are much denser and heavier. The variations in plate thickness are nature's way of partly compensating for the imbalance in the weight and density of the two types of crust. Because continental rocks are much lighter, the crust under the continents is much thicker (as much as 100 km) whereas the crust under the oceans is generally only about 5 km thick. Like icebergs, only the tips of which are visible above water, continents have deep "roots" to support their elevations.
Most of the boundaries between individual plates cannot be seen, because they are hidden beneath the oceans. Yet oceanic plate boundaries can be mapped accurately from outer space by measurements from GEOSAT satellites. Earthquake and volcanic activity is concentrated near these boundaries. Tectonic plates probably developed very early in the Earth's 4.6-billion-year history, and they have been drifting about on the surface ever since-like slow-moving bumper cars repeatedly clustering together and then separating.
Like many features on the Earth's surface, plates change over time. Those composed partly or entirely of oceanic lithosphere can sink under another plate, usually a lighter, mostly continental plate, and eventually disappear completely. This process is happening now off the coast of Oregon and Washington. The small Juan de Fuca Plate, a remnant of the formerly much larger oceanic Farallon Plate, will someday be entirely consumed as it continues to sink beneath the North American Plate.
These four diagrams illustrate the shrinking of the formerly very large Farallon Plate, as it was progressively consumed beneath the North American and Caribbean Plates, leaving only the present-day Juan de Fuca, Rivera, and Cocos Plates as small remnants (see text). Large solid arrows show the present-day sense of relative movement between the Pacific and North American Plates. (Modified from USGS Professional Paper 1515).
Contributors and Attributions
W. Jacquelyne Kious and Robert Tilling (" The Dynamic Earth " via the U.S. Geological Survey )


7.4: Profit Maximization for a Monopolist or Monopolistically Competitive Firm
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The profit maximizing condition can be used to solve the monopolist’s problem. Suppose, as in Demonstration \(\PageIndex{1}\) below, that the inverse demand curve facing the monopolist is \(P = 100 - 3Q\). Since this inverse demand curve is linear, the marginal revenue curve has the same intercept and a slope that is twice as steep. Thus, \(MR = 100 - 6Q\). Suppose further that marginal cost is equal to $4Q. Set \(MR = MC\) or \(100 -6Q = 4Q\)and solve for \(Q\). You get \(Q\) = 10 units. This is the profit maximizing quantity.
Next, use the inverse demand curve to find the profit maximizing price. Although the monopolist equates marginal revenue with marginal cost, it uses the inverse demand curve (not the marginal revenue curve) to set the price. Substituting the profit maximizing quantity into the inverse demand curve, you get a price of \(100-3(10) = $70\).
Notice in the demonstration that the area of the blue rectangle represents profits. Use Demonstration 1 to verify that profits go down if the monopolist does no set the quantity so that \(MR = MC\).
Demonstration \(\PageIndex{1}\). Profit Maximization Problem for a Monopolist
Marginal Cost (MC) = $40.00
Average Total Cost (AC) = $30.00
Profit = (P - AC)Q =$400.00
The steps involved in finding the solution to the firm’s problem under monopolistic competition are exactly the same as the monopolist’s problem above. The primary difference between monopoly and monopolistic competition is that entry is possible in monopolistic competition. If profits are positive, new firms will enter the market and/or existing firms will mimic the successful practices of competitors. When economic profits are zero, there is no additional entry, and the market is at an equilibrium. In a no-entry equilibrium under monopolistic competition, the rectangular area that represents profits will be just equal to the sunk costs that would need to be incurred if the market were to be entered by a new firm. New firms would see entry into the market as unattractive since the profits to be gained would be consumed by the sunk costs of entry.


1.2: Qualitative Method
The Qualitative Method is an anthropological research method designed to map out detailed descriptions of social activities within a culture. A specialist such as an anthropologist enters a foreign/home culture and observe whatever he or she wants to investigate with tools that arrange from taking notes to interviews. The observation(s) may include social norms, activities, religious rituals, cultural ideology and etc. This method doesn’t require any statistical or mathematical measurements (which is the Quantitative Method), but only the written observation of culture within a certain ethnic group.
The reasons behind the observation can vary depending on the intention of the anthropologist. For example, if there’s a social problem within a culture, anthropologists may launch an investigation to figure out the source of the problem. Anthropologists might also apply the qualitative method to create improvements in a social environment. This can take a variety of forms; such as fighting poverty, improving medical care, building new estates and so on. Curious anthropologists often take advantage of the qualitative method. While some might actually use the method to resolve social issues, others might use to learn more about a certain society or group. If someone wanted to learn more about a culture, he or she can observe the lifestyle and find out the opinions of the people to retrieve more information.


1.1: Physics- An Introduction
Learning Objectives
By the end of this section, you will be able to:
- Explain the difference between a principle and a law.
- Explain the difference between a model and a theory.
The physical universe is enormously complex in its detail. Every day, each of us observes a great variety of objects and phenomena. Over the centuries, the curiosity of the human race has led us collectively to explore and catalog a tremendous wealth of information. From the flight of birds to the colors of flowers, from lightning to gravity, from quarks to clusters of galaxies, from the flow of time to the mystery of the creation of the universe, we have asked questions and assembled huge arrays of facts. In the face of all these details, we have discovered that a surprisingly small and unified set of physical laws can explain what we observe. As humans, we make generalizations and seek order. We have found that nature is remarkably cooperative—it exhibits the underlying order and simplicity we so value.
It is the underlying order of nature that makes science in general, and physics in particular, so enjoyable to study. For example, what do a bag of chips and a car battery have in common? Both contain energy that can be converted to other forms. The law of conservation of energy (which says that energy can change form but is never lost) ties together such topics as food calories, batteries, heat, light, and watch springs. Understanding this law makes it easier to learn about the various forms energy takes and how they relate to one another. Apparently unrelated topics are connected through broadly applicable physical laws, permitting an understanding beyond just the memorization of lists of facts.
The unifying aspect of physical laws and the basic simplicity of nature form the underlying themes of this text. In learning to apply these laws, you will, of course, study the most important topics in physics. More importantly, you will gain analytical abilities that will enable you to apply these laws far beyond the scope of what can be included in a single book. These analytical skills will help you to excel academically, and they will also help you to think critically in any professional career you choose to pursue. This module discusses the realm of physics (to define what physics is), some applications of physics (to illustrate its relevance to other disciplines), and more precisely what constitutes a physical law (to illuminate the importance of experimentation to theory).
Science and the Realm of Physics
Science consists of the theories and laws that are the general truths of nature as well as the body of knowledge they encompass. Scientists are continually trying to expand this body of knowledge and to perfect the expression of the laws that describe it. Physics is concerned with describing the interactions of energy, matter, space, and time, and it is especially interested in what fundamental mechanisms underlie every phenomenon. The concern for describing the basic phenomena in nature essentially defines the realm of physics .
Physics aims to describe the function of everything around us, from the movement of tiny charged particles to the motion of people, cars, and spaceships. In fact, almost everything around you can be described quite accurately by the laws of physics. Consider a smart phone (Figure \(\PageIndex{2}\)). Physics describes how electricity interacts with the various circuits inside the device. This knowledge helps engineers select the appropriate materials and circuit layout when building the smart phone. Next, consider a GPS system. Physics describes the relationship between the speed of an object, the distance over which it travels, and the time it takes to travel that distance. When you use a GPS device in a vehicle, it utilizes these physics equations to determine the travel time from one location to another.
Applications of Physics
You need not be a scientist to use physics. On the contrary, knowledge of physics is useful in everyday situations as well as in nonscientific professions. It can help you understand how microwave ovens work, why metals should not be put into them, and why they might affect pacemakers (Figures \(\PageIndex{3}\) and \(\PageIndex{4}\)). Physics allows you to understand the hazards of radiation and rationally evaluate these hazards more easily. Physics also explains the reason why a black car radiator helps remove heat in a car engine, and it explains why a white roof helps keep the inside of a house cool. Similarly, the operation of a car’s ignition system as well as the transmission of electrical signals through our body’s nervous system are much easier to understand when you think about them in terms of basic physics.
Physics is the foundation of many important disciplines and contributes directly to others. Chemistry, for example—since it deals with the interactions of atoms and molecules—is rooted in atomic and molecular physics. Most branches of engineering are applied physics. In architecture, physics is at the heart of structural stability, and is involved in the acoustics, heating, lighting, and cooling of buildings. Parts of geology rely heavily on physics, such as radioactive dating of rocks, earthquake analysis, and heat transfer in the Earth. Some disciplines, such as biophysics and geophysics, are hybrids of physics and other disciplines.
Physics has many applications in the biological sciences. On the microscopic level, it helps describe the properties of cell walls and cell membranes (Figures \(\PageIndex{5}\) and \(\PageIndex{6}\)). On the macroscopic level, it can explain the heat, work, and power associated with the human body. Physics is involved in medical diagnostics, such as x-rays, magnetic resonance imaging (MRI), and ultrasonic blood flow measurements. Medical therapy sometimes directly involves physics; for example, cancer radiotherapy uses ionizing radiation. Physics can also explain sensory phenomena, such as how musical instruments make sound, how the eye detects color, and how lasers can transmit information.
It is not necessary to formally study all applications of physics. What is most useful is knowledge of the basic laws of physics and a skill in the analytical methods for applying them. The study of physics also can improve your problem-solving skills. Furthermore, physics has retained the most basic aspects of science, so it is used by all of the sciences, and the study of physics makes other sciences easier to understand.
Models, Theories, and Laws; The Role of Experimentation
The laws of nature are concise descriptions of the universe around us; they are human statements of the underlying laws or rules that all natural processes follow. Such laws are intrinsic to the universe; humans did not create them and so cannot change them. We can only discover and understand them. Their discovery is a very human endeavor, with all the elements of mystery, imagination, struggle, triumph, and disappointment inherent in any creative effort (Figures \(\PageIndex{7}\) and \(\PageIndex{8}\)). The cornerstone of discovering natural laws is observation; science must describe the universe as it is, not as we may imagine it to be.
We all are curious to some extent. We look around, make generalizations, and try to understand what we see—for example, we look up and wonder whether one type of cloud signals an oncoming storm. As we become serious about exploring nature, we become more organized and formal in collecting and analyzing data. We attempt greater precision, perform controlled experiments (if we can), and write down ideas about how the data may be organized and unified. We then formulate models, theories, and laws based on the data we have collected and analyzed to generalize and communicate the results of these experiments.
A model is a representation of something that is often too difficult (or impossible) to display directly. While a model is justified with experimental proof, it is only accurate under limited situations. An example is the planetary model of the atom in which electrons are pictured as orbiting the nucleus, analogous to the way planets orbit the Sun. (See Figure 9.) We cannot observe electron orbits directly, but the mental image helps explain the observations we can make, such as the emission of light from hot gases (atomic spectra). Physicists use models for a variety of purposes. For example, models can help physicists analyze a scenario and perform a calculation, or they can be used to represent a situation in the form of a computer simulation. A theory is an explanation for patterns in nature that is supported by scientific evidence and verified multiple times by various groups of researchers. Some theories include models to help visualize phenomena, whereas others do not. Newton’s theory of gravity, for example, does not require a model or mental image, because we can observe the objects directly with our own senses. The kinetic theory of gases, on the other hand, is a model in which a gas is viewed as being composed of atoms and molecules.
A law uses concise language to describe a generalized pattern in nature that is supported by scientific evidence and repeated experiments. Often, a law can be expressed in the form of a single mathematical equation. Laws and theories are similar in that they are both scientific statements that result from a tested hypothesis and are supported by scientific evidence. However, the designation law is reserved for a concise and very general statement that describes phenomena in nature, such as the law that energy is conserved during any process, or Newton’s second law of motion, which relates force, mass, and acceleration by the simple equation
\[F =ma.\]
A theory, in contrast, is a less concise statement of observed phenomena. For example, the Theory of Evolution and the Theory of Relativity cannot be expressed concisely enough to be considered a law. The biggest difference between a law and a theory is that a theory is much more complex and dynamic. A law describes a single action, whereas a theory explains an entire group of related phenomena. And, whereas a law is a postulate that forms the foundation of the scientific method, a theory is the end result of that process.
Less broadly applicable statements are usually called principles (such as Pascal’s principle, which is applicable only in fluids), but the distinction between laws and principles often is not carefully made.
MODELS, THEORIES, AND LAWS
Models, theories, and laws are used to help scientists analyze the data they have already collected. However, often after a model, theory, or law has been developed, it points scientists toward new discoveries they would not otherwise have made.
The models, theories, and laws we devise sometimes imply the existence of objects or phenomena as yet unobserved. These predictions are remarkable triumphs and tributes to the power of science. It is the underlying order in the universe that enables scientists to make such spectacular predictions. However, if experiment does not verify our predictions, then the theory or law is wrong, no matter how elegant or convenient it is. Laws can never be known with absolute certainty because it is impossible to perform every imaginable experiment in order to confirm a law in every possible scenario. Physicists operate under the assumption that all scientific laws and theories are valid until a counterexample is observed. If a good-quality, verifiable experiment contradicts a well-established law, then the law must be modified or overthrown completely.
The study of science in general and physics in particular is an adventure much like the exploration of uncharted ocean. Discoveries are made; models, theories, and laws are formulated; and the beauty of the physical universe is made more sublime for the insights gained.
THE SCIENTIFIC METHOD
As scientists inquire and gather information about the world, they follow a process called the scientific method. This process typically begins with an observation and question that the scientist will research. Next, the scientist typically performs some research about the topic and then devises a hypothesis. Then, the scientist will test the hypothesis by performing an experiment. Finally, the scientist analyzes the results of the experiment and draws a conclusion. Note that the scientific method can be applied to many situations that are not limited to science, and this method can be modified to suit the situation.
Consider an example. Let us say that you try to turn on your car, but it will not start. You undoubtedly wonder: Why will the car not start? You can follow a scientific method to answer this question. First off, you may perform some research to determine a variety of reasons why the car will not start. Next, you will state a hypothesis. For example, you may believe that the car is not starting because it has no engine oil. To test this, you open the hood of the car and examine the oil level. You observe that the oil is at an acceptable level, and you thus conclude that the oil level is not contributing to your car issue. To troubleshoot the issue further, you may devise a new hypothesis to test and then repeat the process again.
The Evolution of Natural Philosophy into Modern Physics
Physics was not always a separate and distinct discipline. It remains connected to other sciences to this day. The word physics comes from Greek, meaning nature. The study of nature came to be called “natural philosophy.” From ancient times through the Renaissance, natural philosophy encompassed many fields, including astronomy, biology, chemistry, physics, mathematics, and medicine. Over the last few centuries, the growth of knowledge has resulted in ever-increasing specialization and branching of natural philosophy into separate fields, with physics retaining the most basic facets (Figures \(\PageIndex{10}\)-Figure \(\PageIndex{12}\)). Physics as it developed from the Renaissance to the end of the 19th century is called classical physics . It was transformed into modern physics by revolutionary discoveries made starting at the beginning of the 20th century.
Classical physics is not an exact description of the universe, but it is an excellent approximation under the following conditions: Matter must be moving at speeds less than about 1% of the speed of light, the objects dealt with must be large enough to be seen with a microscope, and only weak gravitational fields, such as the field generated by the Earth, can be involved. Because humans live under such circumstances, classical physics seems intuitively reasonable, while many aspects of modern physics seem bizarre. This is why models are so useful in modern physics—they let us conceptualize phenomena we do not ordinarily experience. We can relate to models in human terms and visualize what happens when objects move at high speeds or imagine what objects too small to observe with our senses might be like. For example, we can understand an atom’s properties because we can picture it in our minds, although we have never seen an atom with our eyes. New tools, of course, allow us to better picture phenomena we cannot see. In fact, new instrumentation has allowed us in recent years to actually “picture” the atom.
LIMITS ON THE LAWS OF CLASSICAL PHYSICS
For the laws of classical physics to apply, the following criteria must be met: Matter must be moving at speeds less than about 1% of the speed of light, the objects dealt with must be large enough to be seen with a microscope, and only weak gravitational fields (such as the field generated by the Earth) can be involved.
Some of the most spectacular advances in science have been made in modern physics. Many of the laws of classical physics have been modified or rejected, and revolutionary changes in technology, society, and our view of the universe have resulted. Like science fiction, modern physics is filled with fascinating objects beyond our normal experiences, but it has the advantage over science fiction of being very real. Why, then, is the majority of this text devoted to topics of classical physics? There are two main reasons: Classical physics gives an extremely accurate description of the universe under a wide range of everyday circumstances, and knowledge of classical physics is necessary to understand modern physics.
Modern physics itself consists of the two revolutionary theories, relativity and quantum mechanics. These theories deal with the very fast and the very small, respectively. Relativity must be used whenever an object is traveling at greater than about 1% of the speed of light or experiences a strong gravitational field such as that near the Sun. Quantum mechanics must be used for objects smaller than can be seen with a microscope. The combination of these two theories is relativistic quantum mechanics, and it describes the behavior of small objects traveling at high speeds or experiencing a strong gravitational field. Relativistic quantum mechanics is the best universally applicable theory we have. Because of its mathematical complexity, it is used only when necessary, and the other theories are used whenever they will produce sufficiently accurate results. We will find, however, that we can do a great deal of modern physics with the algebra and trigonometry used in this text.
Exercise \(\PageIndex{1}\)
A friend tells you he has learned about a new law of nature. What can you know about the information even before your friend describes the law? How would the information be different if your friend told you he had learned about a scientific theory rather than a law?
- Answer
-
Without knowing the details of the law, you can still infer that the information your friend has learned conforms to the requirements of all laws of nature: it will be a concise description of the universe around us; a statement of the underlying rules that all natural processes follow. If the information had been a theory, you would be able to infer that the information will be a large-scale, broadly applicable generalization.
PHET EXPLORATIONS: EQUATION GRAPHER
Learn about graphing polynomials. The shape of the curve changes as the constants are adjusted. View the curves for the individual terms (e.g. \(y=bx\)) to see how they add to generate the polynomial curve.
Summary
- Science seeks to discover and describe the underlying order and simplicity in nature.
- Physics is the most basic of the sciences, concerning itself with energy, matter, space and time, and their interactions.
- Scientific laws and theories express the general truths of nature and the body of knowledge they encompass. These laws of nature are rules that all natural processes appear to follow.
Glossary
- classical physics
- physics that was developed from the Renaissance to the end of the 19th century
- physics
- the science concerned with describing the interactions of energy, matter, space, and time; it is especially interested in what fundamental mechanisms underlie every phenomenon
- model
- representation of something that is often too difficult (or impossible) to display directly
- theory
- an explanation for patterns in nature that is supported by scientific evidence and verified multiple times by various groups of researchers
- law
- a description, using concise language or a mathematical formula, a generalized pattern in nature that is supported by scientific evidence and repeated experiments
- scientific method
- a method that typically begins with an observation and question that the scientist will research; next, the scientist typically performs some research about the topic and then devises a hypothesis; then, the scientist will test the hypothesis by performing an experiment; finally, the scientist analyzes the results of the experiment and draws a conclusion
- modern physics
- the study of relativity, quantum mechanics, or both
- relativity
- the study of objects moving at speeds greater than about 1% of the speed of light, or of objects being affected by a strong gravitational field
- quantum mechanics
- the study of objects smaller than can be seen with a microscope


3.6: Global Trade Agreements and Organizations
What you’ll learn to do: describe global trade agreements and economic organizations that regulate and promote global trade
In this section, you’ll learn about the organizations that oversee global economic cooperation and help facilitate global trade agreements.
Learning Objectives
- Describe the role of the World Bank in promoting global economic development
- Describe the role of trade agreements in global business
The World Trade Organization (WTO)
In the post–World War II environment, countries came to realize that a major component of achieving any degree of global peace was global cooperation—politically, economically, and socially. The intent was to level the trade playing field and reduce economic areas of disagreement, since inequality in these areas could lead to more serious conflicts. Nations agreed to work together to promote free trade and, with the help of key international organizations like the World Trade Organizations, they entered into bilateral and multilateral agreements.
GATT: How the World Trade Organization Got Its Start
Before you begin your reading on the World Trade Organization (WTO), take a few minutes to watch the following video that will give you some background on General Agreement on Tariffs and Trade (GATT) and explain how it grew into the WTO we know today. Remember, the world is much smaller today than when your parents and grandparents were growing up, and international trade hasn’t always been the norm. After watching the video, consider how impossible world trade would be without some type of agreement among nations.
Enjoy!
As you saw in the video, what began with one agreement (GATT) eventually evolved into the WTO. In fact, GATT was the only multilateral instrument governing global trade from 1946 until 1995. Given the difficulty of trying to regulate trade among more than one hundred nations according to a single document, it’s easy to see why the WTO came into existence. It became clear to the participating nations that GATT was incapable of adapting to an increasingly globalized world economy. Moreover, when the Uruguay Round of GATT negotiations was launched in September 1986, it marked the largest global effort to structure trade in history. Today, GATT still exists as the WTO’s umbrella treaty for trade in goods, but it’s no longer the only legally binding global-trade agreement.
What does the WTO actually do? Among its various functions, the most important are the following:
- Oversees the implementation and administration of the agreements between nations that fall under the WTO’s scope of authority
- Provides a forum for negotiations and settling disputes among nations.
In recent years, the WTO has also made it a priority to assist developing nations as they come under WTO regulation. Many developing countries and emerging markets lack the experience and technical expertise needed to deal with large and very comprehensive trade agreements. The WTO provides them with critical training and support, thereby ensuring that the WTO is inclusive and equitable toward both the wealthiest and the poorest nations in the world.
Part of the nondiscrimination mandate of the WTO is most-favored-nation (MFN) status. Most-favored-nation status requires that a WTO member must apply the same terms and conditions to trade with any and all other WTO members. In other words if a country grants another country (even a non-WTO member) a special favor, then every other WTO member must get the same treatment.  In other words you couldn’t just give gum or candy to your best friends, and if you didn’t have enough for everyone in the class, then nobody got any. That, in effect, is how most-favored-nation status works.
One of the other key elements to the success of the WTO is its transparency requirement. WTO members are required to publish their trade regulations and follow a system that allows external parties to review and evaluate any administrative decisions and their impact on trade regulations. When a WTO nation changes its trade policies, those changes must be reported to the WTO.
Overall, the WTO’s mission is to improve the stability and predictability of global trade. As a result, it tends to support free-trade, as opposed to protectionist, policies, and strongly discourages the use of quotas and other such restrictions on imports.
Whether or not the WTO is doing its duty and accomplishing its mission is a matter of ongoing debate. Nonetheless, the WTO currently has 104 members and twenty observer governments. WTO member states account for almost 97 percent of global trade and 98 percent of global GDP. Once the twenty observer governments become members, it is possible that the WTO will oversee the entire world economy. What began in 1947 in Geneva, with twenty-three nations focused solely on tariff reduction, has grown into a truly global organization that deals with agriculture, labor standards, environmental issues, competition, and intellectual property rights.
The World Bank
World Bank Group president Jim Yong Kim visits an integrated child development services and skills center in Delhi, India.
Created in 1944 at the Bretton Woods Conference in New Hampshire, the World Bank is an international financial institution that provides loans for capital programs to developing countries. It comprises two institutions: the International Bank for Reconstruction and Development (IBRD), and the International Development Association (IDA). Originally, the IBRD was tasked with supporting post-war reconstruction, but it has evolved to include the present-day mandate to alleviate poverty worldwide. The World Bank is a component of the World Bank Group, which is part of the United Nations system. The World Bank is comprised of 189 member countries represented by a board of governors. Although headquartered in Washington DC, the World Bank has a presence in almost every nation in the world.
The World Bank has set two goals to achieve by 2030:
- End extreme poverty by decreasing the percentage of the world’s population that live on less than US$1.90 per day to no more than 3 percent
- Promote shared prosperity by fostering the income growth of the bottom 40 percent in every country
The World Bank’s primary function is providing low-interest loans and grants to developing countries. It tends to fund projects focused on education, infrastructure, natural-resource management, and public health. In many instances, the World Bank provides technical assistance as well as research and policy advice to developing nations. One of the projects currently underway is the Education Sector Support Project for the Republic of the Congo. The primary objective of this project is to improve education outcomes for primary- and secondary-school children by providing quality education in an appropriate teaching and learning environment. Other World Bank projects are aimed at improving basic infrastructure, such as building and maintaining safe water supplies and sanitary sewer systems in Africa and parts of Asia. For developing nations, many of these improvements would be impossible without the World Bank’s help. Although the World Bank has come under fire in the past for budget overruns and poor project oversight, its role in promoting economic development has been undeniable.
The following video shows how a World Bank project works:
The International Monetary Fund (IMF)
The International Monetary Fund (IMF) is an international organization headquartered in Washington, D.C., comprised of 189 member countries. The IMF works to foster global growth and economic stability by providing policy, advice, and financing to its members. It also works with developing nations to help them reduce poverty and achieve macroeconomic stability. Formed in 1944 at the Bretton Woods Conference in New Hampshire, it came into formal existence in 1945 with twenty-nine member countries and the goal of reconstructing the international payment system. It now plays a central role in the management of balance-of-payments difficulties and international financial crises.
IMF member countries contribute funds to a pool, from which they can borrow if they are experiencing balance-of-payments problems. The rationale for this arrangement is that private international capital markets function imperfectly, and many countries have limited access to financial markets. Without access to IMF financing, many countries can only correct large external payment imbalances through drastic measures that can have adverse effects on their own economies and the world’s. The IMF provides alternate sources of financing to countries in need that would not otherwise be available to them.
When the IMF was founded, its primary functions were to provide short-term capital to aid the balance of payments and to oversee fixed-exchange-rate arrangements between countries, thus helping national governments manage their exchange rates and prioritize economic growth. This assistance was meant to prevent the spread of international economic crises. The IMF was also formed to help put the pieces of the international economy back together after the Great Depression and World War II. In addition, it also sought to provide capital investments for economic growth and infrastructure projects.
The IMF’s role was fundamentally altered by floating exchange rates post-1971. At that point the organization began examining the economic policies of its loan recipients to determine whether a shortage of capital was due to economic fluctuations or economic policy. The IMF also researched what types of government policy would ensure economic recovery. The current challenge is to help countries implement economic policies that reduce the frequency of crises among the emerging-market countries, especially the middle-income countries that are vulnerable to massive capital outflows. In order to meet this challenge, the IMF’s activities have expanded beyond the oversight of exchange rates to surveillance of the overall macroeconomic performance of its member countries. Today it plays an active role in shaping and managing economic policy around the world.
The following video gives a good overview of the IMF and its role in promoting global trade.
Trade Agreements
So far you have seen how international organizations such as the WTO, IMF, and World Bank support global trade, but this is only part of the story. Where global trade really gets a boost is from trade agreements (also called trade blocs). This where the term “global economic integration” gets its legs— from the process of modifying barriers among and between nations to create a more fully integrated global economy. Trade agreements vary in the amount of free trade they allow among members and with nonmembers; each has a unique level of economic integration. We will look at four: regional trade agreement (RTA) (also called a “free trade area”), customs unions, common markets, and economic unions.
Regional trade agreements are reciprocal trade agreements between two or more partners (nations). Almost all countries are part of at least one RTA. Under an RTA, countries “huddle together,” forming an international community that facilitates the movement of goods and services between them. For example, the North American Free Trade Agreement (NAFTA) enacted between Canada, the U.S., and Mexico facilitates trade among these countries through tariff reductions and elimination. The Association of Southeast Asian Nations (ASEAN), shown below, provides for the free exchange of trade, service, labor, and capital across ten independent member nations to provide a balance of power to China and Japan. The Central American Free Trade Agreement (CAFTA) (Costa Rica, Dominican Republic, Guatemala, Honduras, Nicaragua, and El Salvador) eliminated tariffs on more than 80 percent of U.S. exports and opened U.S. trade restrictions for Central American sugar, textiles, and apparel imports, thereby reducing costs on these products for American consumers [1] .
The Association of Southeast Asian Nations (ASEAN) as of 2015.
Customs unions are arrangements among countries whereby the parties agree to allow free trade on products within the customs union, and they agree to a common external tariff (CET) on imports from the rest of the world. It is this CET that distinguishes a customs union from a regional trade agreement. It is important to note that although trade is unrestricted within the union, customs unions do not allow free movement of capital and labor among member countries. An example is the customs union of Russia, Belarus, and Kazakhstan, which was formed in 2010. These countries eliminated trade barriers among themselves but have also agreed to some common policies for dealing with nonmember countries.
Common markets are similar to customs unions in that they eliminate internal barriers between members and adopt common external barriers against nonmembers. This difference is that common markets also allow free movement of resources (e.g., labor) among member countries. An example of a common market is the Economic Community of West African States (ECOWAS), comprised of Benin, Burkina Faso, Cape Verde, Gambia, Ghana, Guinea, guinea-Bissau, Ivory Coast, Liberia, Mali, Niger, Nigeria, Senegal, Sierra Leone, and Togo.
An even more economically integrated arrangement is the economic union . Economic unions eliminate internal barriers, adopt common external barriers, permit free movement of resources (e.g., labor), AND adopt a common set of economic policies. The best-known example of an economic union is the European Union (EU). EU members all use the same currency, follow one monetary policy, and trade with one another without paying tariffs.
The following video further explains and compares the different types of trade agreements:
- USTR, CAFTA-DR Dominican Republic-Central America FTA ↵


12.7: Linking global biogeochemical cycles
Eutrophication and Dead Zones
Nutrients in soil and water are generally beneficial when they exist at naturally occurring levels. Nitrogen fertilizers have been applied to farm fields for decades in order to maximize production of agricultural lands. However, an unintended consequence is that the same nutrients can be detrimental to aquatic ecosystems when introduced excessively for agricultural or other purposes. Nitrogen (N) and Phosphorus (P) are introduced by fertilizers that are used intensively in agriculture, as well as golf courses and some lawns and gardens. Farm animal waste and sewage also provide large amounts of reactive N and P. Phosphorus was formerly used heavily as an additive in laundry and dishwater detergents, but since the 1970's it has been phased out in both through a combination of state and federal regulations. Overall, our modern society has altered the global N and P cycles such that there is an overabundance in many settings.
Excessive nutrients (not utilized) are often washed into drainage ways, streams, and rivers during rainfall and storm events. Eutrophication occurs when excess phosphorus and nitrogen from fertilizer runoff or sewage causes excessive growth of algae. Algal blooms that block light and therefore kill aquatic plants in rivers, lakes, and seas. The subsequent death and decay of these organisms depletes dissolved oxygen, which leads to the death of aquatic organisms such as shellfish and fish. This process is responsible for dead zones , large areas in lakes and oceans near the mouths of rivers that are periodically depleted of their normal flora and fauna, and for massive fish kills, which often occur during the summer months (figure \(\PageIndex{1}\)). There are more than 500 dead zones worldwide. Phosphate and nitrate runoff from fertilizers also negatively affect several lake and bay ecosystems including the Chesapeake Bay in the eastern United States.
One of the worst dead zones is off the coast of the United States in the Gulf of Mexico (figure \(\PageIndex{1}\)). Fertilizer runoff from the Mississippi River basin created a dead zone, which reached its peak size of 8,776 square miles in 2017. The Mississippi River dumps high-nutrient runoff from its drainage basin that includes vast agricultural lands in the American Midwest. Increased algal growth produced by these nutrients has affected important shrimp fishing grounds in the Gulf. The primary source of the nutrients is the heavily tile-drained areas of farmland in the Midwest corn and soybean belt (SW Minnesota, N Iowa, NE Illinois, N Indiana and NW Ohio). Improved soil drainage systems over the past century or more have allowed for effective transport of nitrate compounds as stormwater runoff into drainage basins (Ohio River, Wabash River, Illinois River, Missouri River, etc.) that feed into the Mississippi River. In other words, the same drainage tiles that allow for the agricultural benefit of having rich bottomland/wetland soils in production, have the disadvantage of increased and more rapid movements of nitrate solutes to the Gulf of Mexico. Such large-scale problems, across state governmental boundaries, can only be fully addressed in the future with a national system of incentives, regulations, or laws.
Figure \(\PageIndex{1}\): Dead zones occur when phosphorus and nitrogen from fertilizers cause excessive growth of microorganisms, which depletes oxygen and kills fauna. This map shows dead zones around the world in 2008. Worldwide, large dead zones are found in coastal areas of high population density. (credit: NASA Earth Observatory)
In addition to fertilizers, Nitrogen inputs to watersheds can also include atmospheric deposition, livestock waste, and sewage, but nitrogen fertilizers comprise a significant majority of the input to monitored streams, particularly in springtime when much fertilizer is applied. Possible solutions to this problem include encouraging farmers to apply a more limited quantity of fertilizer in the spring (only as much as necessary), rather than in the fall, to allow for considerably less time for stormwater or meltwater runoff. Other solutions include maintaining cover crops, or restoring wetlands in key locations to contain nitrate losses. An overall strategy that limits the excess capacity of nutrients can simultaneously benefit farmers (by limiting cost), the ecology of stream watersheds and coastal ecosystems (also locally stressed by oil spills and other pollution). Over the long term, more efforts will need to be made in the Mississippi River Basin, and globally in similarly stressed agricultural or urban watersheds (figure \(\PageIndex{1}\)), to improve the health and sustainability of our soil, land, and aquatic ecosystems.
Everyday Connection: Chesapeake Bay
The Chesapeake Bay has long been valued as one of the most scenic areas on Earth; it is now in distress and is recognized as a declining ecosystem. In the 1970s, the Chesapeake Bay was one of the first ecosystems to have identified dead zones, which continue to kill many fish and bottom-dwelling species, such as clams, oysters, and worms (figure \(\PageIndex{2}\)). Several species have declined in the Chesapeake Bay due to surface water runoff containing excess nutrients from artificial fertilizer used on land. The source of the fertilizers (with high nitrogen and phosphate content) is not limited to agricultural practices. There are many nearby urban areas and more than 150 rivers and streams empty into the bay that are carrying fertilizer runoff from lawns and gardens. Thus, the decline of the Chesapeake Bay is a complex issue and requires the cooperation of industry, agriculture, and everyday homeowners.
Figure \(\PageIndex{2}\): This (a) satellite image shows the Chesapeake Bay, an ecosystem affected by phosphate and nitrate runoff. A (b) member of the Army Corps of Engineers holds a clump of oysters being used as a part of the oyster restoration effort in the bay. (credit a: modification of work by NASA/MODIS; credit b: modification of work by U.S. Army)
Of particular interest to conservationists is the oyster population; it is estimated that more than 200,000 acres of oyster reefs existed in the bay in the 1700s, but that number has now declined to only 36,000 acres. Oyster harvesting was once a major industry for Chesapeake Bay, but it declined 88 percent between 1982 and 2007. This decline was due not only to fertilizer runoff and dead zones but also to overexploitation . Oysters require a certain minimum population density because they must be in close proximity to reproduce. Human activity has altered the oyster population and locations, greatly disrupting the ecosystem.
The restoration of the oyster population in the Chesapeake Bay has been ongoing for several years with mixed success. Not only do many people find oysters good to eat, but they also clean up the bay. Oysters are filter feeders, and as they eat, they clean the water around them. In the 1700s, it was estimated that it took only a few days for the oyster population to filter the entire volume of the bay. Today, with changed water conditions, it is estimated that the present population would take nearly a year to do the same job.
Restoration efforts have been ongoing for several years by non-profit organizations, such as the Chesapeake Bay Foundation. The restoration goal is to find a way to increase population density so the oysters can reproduce more efficiently. Many disease-resistant varieties (developed at the Virginia Institute of Marine Science for the College of William and Mary) are now available and have been used in the construction of experimental oyster reefs. Efforts to clean and restore the bay by Virginia and Delaware have been hampered because much of the pollution entering the bay comes from other states, which stresses the need for inter-state cooperation to gain successful restoration.
The new, hearty oyster strains have also spawned a new and economically viable industry—oyster aquaculture—which not only supplies oysters for food and profit, but also has the added benefit of cleaning the bay.
References
Cell Press. (2020, August 6). Researchers hope to save seabirds by calculating the value of their excrement. Retrieved August 7, 2020 from ScienceDaily .
Attributions
Modified by Kyle Whittinghill (University of Pittsburgh) and Melissa Ha from the following sources:
- Biogeochemical Cycles , Energy , and Energy Enters Ecosystems Through Photosynthesis from Environmental Biology by Matthew R. Fisher (licensed under CC-BY )
- Carbon Cycle and Nitrogen Cycle from Biology by John W. Kimball (licensed under CC-BY )
- Energy Flow through Ecosystems from General Biology by OpenStax (licensed under CC-BY )
- Soil and Sustainability and Biogeochemical Cycles and the Flow of Energy in the Earth System from Sustainability: A Comprehensive Foundation by Tom Theis and Jonathan Tomkin, Editors (licensed under CC-BY ). Download for free at CNX .
- Cycling of Matter from AP Environmental Science by University of California College Prep, University of California (licensed under CC-BY ). Download for free at CNX .
- Nutrient Cycles from Life Sciences Grade 10 by Siyavula ( CC-BY )
-
Samantha Fowler (Clayton State University), Rebecca Roush (Sandhills Community College), James Wise (Hampton University). Original content by OpenStax (CC BY 4.0; Access for free at https://cnx.org/contents/b3c1e1d2-83...4-e119a8aafbdd ).
20.2: Biogeochemical Cycles by OpenStax , is licensed CC BY


6.4: Entering Data
Learning Outcomes
- Add data to a table.
Excel workbooks are used to organize data very clearly. Numerical data can be used in a variety of ways, some of which we will examine in later modules. The first step, however, is simply to enter data into a table.
First, open a blank workbook. Next, click on the first cell for your data: this will almost always be A1.
If you wish to organize your data in a column, you will hit ENTER to move to the next cell down. In this case, A2.
If you wish to organize your data in a row, you will hit the Tab key to move to the next cell over. In this case, the next cell over is B1.
Enter all of your data into each individual cell until you are ready to save your workbook.
Contributors and Attributions
- Enter Data into a Table. Authored by : Shelli Carter. Provided by : Lumen Learning. License : CC BY: Attribution