Ch 17, ch 18, ch 19, CH 20, ch 22, ch 21

The loss of water in the urine due to unreabsorbed solutes is known as ________.

osmotic diuresis

Bronchioles and systemic arterioles constrict. A. PO2 increases B. PCO2 increases C. PO2 decreases D. PCO2 decreases

pCO2 decreases

The pressure contributed by a single gas in a mixture of gases is known as ________.

partial pressure

The opposing layers of pleural membrane are held together by a thin film of ________.

pleural fluid

Air flows into lungs because of ________ created by ________.

pressure gradients, pumps

The plasma concentration at which all of the renal carriers for a given substance are saturated is the ________.

renal threshold

Diffusion rate is directly proportional to ________ and ________.

surface area and concentration gradient

The substance produced by the lungs to reduce surface tension is called ________.

surfactant

Neural control of GFR is mediated by ________ that innervate ________ receptors on vascular smooth muscle causing ________.

sympathetic neurons, alpha, vasoconstriction

The primary function of the alveoli is ________.

the exchange of gases between them and the blood

The volume of air moved in a single respiration is called the ________.

tidal volume

When fluid flow through the distal tubule increases as a result of increased GFR, the macula densa cells send a chemical message to the neighboring afferent arteriole. The afferent arteriole constricts, increasing resistance and decreasing GFR. This type of autoregulation involving both the kidney tubule and the arteriole is known as ________.

tubuloglomerular feedback

The cells of the lung that produce the substance that lowers surface tension are ________.

type II alveolar cells

________ is a condition of insulin deficiency from beta cell destruction

type ii diabetes mellitus

Urine is carried to the external environment by the ________.

urethra

After it is formed, urine is temporarily stored in the ____.

urinary bladder

List the four basic processes of the digestive system, and describe each

1. Digestion is the chemical and mechanical breakdown of foods into smaller units. 2. Absorption is the active or passive transfer of substances from the lumen of the GI tract to the extracellular fluid. 3. Motility is the movement of material in the GI tract as a result of muscle contraction. 4. Secretion refers to both transepithelial transfer of water and ions from the ECF to digestive tract lumen and also the release of substances synthesized by GI epithelial cells.

What are the functions of pleural fluid?

1. It creates a moist, slippery surface so opposing membranes can slide across one another as the lungs move within the thorax. 2. It holds the lungs tight against the thoracic wall.

What are the two possible causes of lower alveolar PO2? Give examples of each

1. The composition of the inspired air is abnormal. Altitude affects oxygen content of air. 2. Alveolar ventilation is inadequate. Pathological factors include increased airway resistance (asthma), decreased lung compliance (fibrosis), and overdoses of drugs or alcohol.

Name three pathological changes that adversely affect gas exchange

1. a decrease in the amount of alveolar surface area available for gas exchange 2. an increase in the thickness of the alveolar membrane 3. an increase in the diffusion distance between the alveoli and the blood

What are the three ways CO2 is transported in blood? Approximately what percentage is transported by each way?

1. attached to hemoglobin, 23% 2. dissolved, 7% 3. as bicarbonate, 70%

List and summarize the forces that influence filtration across the walls of glomerular capillaries

1. hydrostatic pressure 2. colloid osmotic pressure 3. hydrostatic fluid pressure See the "Filtration Occurs Because of Hydrostatic Pressure in Capillaries" section of the chapter.

) An explorer has been lost in the desert for two days with very little water. As a result, you would expect to observe A) elevated vasopressin levels. B) decreased blood osmolarity. C) normal urine production. D) increased blood volume. E) cells enlarged with fluid.

A

A buffer A) moderates changes in pH. B) always increases pH. C) always decreases pH. D) binds or releases bicarbonate ions.

A

A person who suffers from emphysema will exhibit signs of A) respiratory acidosis. B) respiratory alkalosis. C) metabolic acidosis. D) metabolic alkalosis. E) None of the answers are correct.

A

Abnormal fat and amino acid metabolism may lead to the condition called A) ketoacidosis. B) lactic acidosis. C) metabolic alkalosis. D) respiratory acidosis.

A

Air moves into the lungs because A) the gas pressure in the lungs is less than outside pressure. B) the volume of the lungs decreases with inspiration. C) the thorax is muscular. D) contraction of the diaphragm decreases the volume of the pleural cavity. E) All of the answers are correct.

A

Match the factor with its effect on the affinity of hemoglobin for oxygen. A. Increase B. Decrease increased pH

A

________ involve short segments of intestine that alternately contract and relax. They are responsible for ________. A) Segmental contractions, mixing B) Peristaltic contractions, pushing a bolus forward C) Segmental contractions, pushing a bolus forward D) Peristaltic contractions, mixing

A

________ is intestinal gas produced by bacteria in the colon during the metabolism of indigestible carbohydrates. A) Flatus B) Defecation C) Haustra D) Tenia Coli

A

increased respiratory rate and/or volume due to increased metabolism A. hyperpnea B. hyperventilation C. tachypnea D. dyspnea E. apnea

A

thickened alveolar membrane and decreased lung compliance A. fibrotic lung disease B. emphysema C. asthma D. pulmonary edema

A

Describe a ketogenic diet. What are the pros and cons of such a diet? How is ketosis related to diabetes mellitus?

A ketogenic diet is low in carbohydrate and high in protein and fat. Ketone bodies are produced as fat is metabolized. Pros: rapid initial weight loss and caloric restriction. Cons: initial weight loss represents loss of glycogen and water, rather than fat; dehydration, vitamin and mineral deficiency; and kidney problems. Untreated diabetics cannot metabolize carbohydrates normally, so their diets are functionally ketogenic.

A. At a PO2 of 80 mm Hg, which type of hemoglobin binds more oxygen? B. At a PO2 of 40 mm Hg, which type of hemoglobin has released more oxygen to the cell? C. Explain the significance of the differences in fetal and maternal hemoglobin affinity. D. If a worm lived in low oxygen mud flats where the PO2 is 60 mm Hg, which type of hemoglobin would be better for it to have? Explain.

A. Fetal hemoglobin has a higher affinity for oxygen than maternal hemoglobin at that oxygen pressure. B. Maternal hemoglobin releases oxygen more readily than fetal hemoglobin at that oxygen pressure. C. The higher affinity of fetal hemoglobin for oxygen ensures a net transfer of oxygen from the maternal blood to the fetal blood in the placenta. While unloading from fetal hemoglobin to fetal tissues is less favorable due to the higher affinity, the high rate of oxygen consumption in fetal tissues and consequent low oxygen pressure ensures unloading will occur. D. The fetal form of hemoglobin would be better in this situation, because it has a higher affinity for the oxygen at this pressure. Thus, the worm's blood would become more saturated, and more oxygen would then be available for the worm's cells.

Muna came down with the flu. She experienced severe vomiting, determined to be primarily stomach contents, for three days, and now is having chest pains. She is calling one of her symptoms "heartburn," but reported that it felt as if she had swallowed a small apple whole. Certain that she was having a heart attack, Muna rushed to the doctor. The doctor took her history and symptoms, and reassured her that she only had esophagitis. How did the physician conclude this? Is her blood pH higher or lower than normal?

Acid reflux irritated the esophageal lining, causing it to swell. Her pH is higher than normal due to loss of H+ from her stomach.

Draw a map that shows the renal compensation for acidosis. Draw another map for alkalosis.

Answer: Figure 20.18 shows compensations for both acidosis and alkalosis.

Compare and contrast insulin and glucagon

Answers will vary but should include information in Tables 22.1 and 22.3 in the chapter.

________ is characterized by an increased airway resistance and decreased ventilation

Asthma

) A primary target tissue for insulin is the A) brain only. B) liver only. C) intestine only. D) brain and liver. E) brain, liver, and intestine.

B

A drug that blocks the action of carbonic anhydrase in parietal cells would result in A) a lower pH during gastric digestion. B) a higher pH during gastric digestion. C) decreased production of pepsinogen by chief cells. D) increased protein digestion in the stomach. E) decreased gastrin production

B

A drug that blocks the action of the hormone cholecystokinin would affect A) the amount of bile produced by the liver. B) pancreatic secretions. C) the level of intestinal gastrin. D) secretions of the duodenal glands. E) All of the answers are correct

B

A molecule that blocks the activity of carbonic anhydrase would A) interfere with oxygen binding to hemoglobin. B) cause an increase in blood pH. C) increase the amount of bicarbonate formed in the blood. D) decrease the amount of carbon dioxide dissolved in the plasma. E) All of the answers are correct.

B

A person who suffers from hyperventilation will exhibit signs of A) respiratory acidosis. B) respiratory alkalosis. C) metabolic acidosis. D) metabolic alkalosis. E) None of the answers are correct

B

During the cephalic phase of gastric secretion, A) the stomach responds to distention. B) secretin inhibits parietal and chief cells. C) there is an increased flow of action potentials along the vagus nerve to the stomach. D) the intestine reflexively inhibits gastric emptying. E) production of gastric juice slows down.

C

Enzymatic digestion of fats involves ________, which breaks down ________. A) amylase, carbohydrates B) bile, cholesterol C) lipase, triglycerides D) pepsin, proteins

C

G cells of the stomach secrete A) cholecystokinin. B) secretin. C) gastrin. D) enterokinase. E) pepsin.

C

Match the term to its definition. A. metabolism B. catabolism C. anabolism large molecules synthesized from smaller ones

C

Rugae, plicae, and villi are all features that accomplish A) secretion of enzymes. B) secretion of hormones. C) an increase in surface area. D) immune function. E) mechanical digestion

C

The brain neurotransmitter that is an important stimulus for food intake is A) ghrelin. B) leptin. C) neuropeptide Y. D) orexin. E) insulin.

C

The feeding and satiety centers are located in the A) medulla oblongata. B) pons. C) hypothalamus. D) cerebrum. E) cerebellum.

C

The hormone vasopressin A) is secreted by the anterior pituitary gland in response to changes in blood osmolarity. B) stimulates the kidneys to retain sodium ions. C) stimulates the kidneys to conserve water. D) stimulates the kidneys to produce a large volume of urine. E) All of the answers are correct.

C

The lungs are enclosed in ________ membranes. A) pericardial B) pulmonary C) pleural D) thoracic E) costal

C

The nutrients that yield the most energy per gram when metabolized are A) carbohydrates. B) proteins. C) fats. D) nucleic acids. E) vitamins.

C

The process of filtration in the kidney is most accurately described as A) highly specific. B) completely nonspecific. C) relatively nonspecific.

C

Which statement is NOT true? A) The blood supply to the kidneys comes through the renal arteries. B) As much as one fourth of the cardiac output may flow to the kidneys at any given moment. C) The kidneys do not reabsorb filtered waste products. D) The urinary bladder is filled by two ducts, called ureters, and emptied by the single urethra. E) Women are more likely to develop urinary tract infections than men.

C

Why is sodium actively reabsorbed in the nephron? A) to decrease osmolarity inside the nephron B) to make urine less concentrated C) to increase passive reabsorption of water D) to decrease blood pressure

C

increased airway resistance A. fibrotic lung disease B. emphysema C. asthma D. pulmonary edema

C

Hemoglobin binds to and has a much higher affinity for carbon monoxide (CO) than for oxygen. CO is colorless and odorless and can be produced in homes heated by natural gas; victims usually do not realize they are being poisoned and often die in their sleep. Describe the likely changes in a CO poisoning victim.

CO will gradually displace O2 on hemoglobin molecules. While this increases O2 unloading in tissues, it will significantly decrease O2 loading in lungs, therefore hypoxia will result. Victims gradually lose consciousness as the brain tissues become hypoxic.

Ongoing diseases in which air flow during expiration is diminished are known as ________.

COPD

Essential nutrients are those that our cells require but cannot make, and thus they must be present in the diet. Only some amino acids and some fatty acids are essential. What does that suggest about extreme diets that eliminate fats or proteins? What does that suggest about our carbohydrate intake? Describe the typical American diet, in terms of relative amounts of ingested carbohydrates, fats, proteins, and nucleic acids. Propose some explanations for why one of those is predominant.

Complete elimination of proteins or fats would eventually be fatal. Carbohydrates need not be consumed at all, from the standpoint of essential nutrients. In reality, however, a carbohydrate-free diet would cause metabolic problems because of consequences of manufacturing glucose from lipids and proteins, as described in Chapter 22 in the text. About half of the typical dietary intake is carbohydrate, with most of the remainder in the form of fats and proteins. Carbohydrates are the primary molecule in plant products, which makes up most of what we eat because of abundance and price.

List and explain the factors that influence gas diffusion in the lungs

Concentration gradient, surface area, membrane thickness, and diffusion distance are the four factors. Increasing the concentration gradient and surface area will increase the rate of diffusion across the lungs while increasing membrane thickness and diffusion distance will decrease the rate of diffusion in the lungs.

An increase in plasma potassium levels is properly called A) hypernatremia. B) hyperpotassemia. C) hyperpotasseplasmia. D) hyperkalemia. E) hypercalcemia.

D

Atrial natriuretic peptide A) increases GFR. B) inhibits release of renin. C) stimulates release of renin. D) increases GFR and inhibits release of renin. E) increases GFR and stimulates release of renin.

D

The reactions where fats are broken down into glycerol and fatty acids are called A) glycerolysis. B) glycolysis. C) gluconeogenesis. D) lipolysis. E) liposuction.

D

The release of many GI tract hormones is stimulated by a particular food or substance. Which hormone is INCORRECTLY paired with its stimulus? A) CCK — fatty foods B) secretin — acid in the small intestine C) GIP — glucose in the small intestine D) motilin — acid in the stomach E) gastrin — peptides and amino acids

D

The synthesis of glucose from a noncarbohydrate precursor is referred to as A) glycogenesis. B) glycogenolysis. C) glycolysis. D) gluconeogenesis. E) glycogen.

D

The two organ systems that work together to regulate most aspects of the body's water balance are A) digestive and respiratory. B) urinary and respiratory. C) cardiovascular and respiratory. D) urinary and cardiovascular. E) digestive and cardiovascular.

D

Thirst is A) controlled by centers in the hypothalamus. B) triggered by decreased osmolarity. C) relieved only when plasma osmolarity is increased. D) controlled by centers in the hypothalamus and triggered by increased osmolarity. E) controlled by centers in the hypothalamus, triggered by increased osmolarity, and relieved only when plasma osmolarity is decreased.

D

Water reabsorption by the kidneys is a result of A) both passive and active transport processes. B) cotransport with ions. C) exchange with ions. D) osmosis.

D

Which is NOT a kidney filtration barrier? A) glomerular capillary endothelium B) basal lamina C) Bowman's capsule epithelium D) juxtaglomerular apparatus

D

What is Dalton's law? Why is it important?

Dalton's law states that the total air pressure in a mixture of gases is the sum of the pressures contributed by each individual gases (the partial pressures). It is important because the air that we breathe is a mixture of gases, gas pressure is related to amount of gas, and the respiratory system is regulated in part by the partial pressures of oxygen and carbon dioxide in the body.

Presence of glucose in the urine is evidence of what condition?

Diabetes mellitus

) GLUT4 transporters are A) only stored in cytoplasmic vesicles. B) only inserted in response to glucagon. C) only inserted into the plasma membrane by endocytosis. D) only found in adipose and skeletal muscles. E) stored in cytoplasmic vesicles and found in adipose and skeletal muscles.

E

A hormone that helps to regulate the sodium ion concentration of the blood is A) cortisol. B) parathormone. C) thymosin. D) somatotropin. E) aldosterone.

E

A rise in angiotensin II levels would result in increased A) blood pressure. B) retention of sodium ions at the kidney. C) water retention. D) blood volume. E) All of these effects.

E

After ingestion of carbohydrates in an insulin-deficient diabetic, ________ would happen. A) protein degradation B) fat synthesis C) ketone production D) glycolysis E) protein degradation and ketone production

E

Amylases, the enzymes used to digest carbohydrates, are secreted by A) salivary glands into the mouth only. B) gastric glands into the stomach only. C) the pancreas into the intestine only. D) salivary glands into the mouth and gastric glands into the stomach. E) salivary glands into the mouth and the pancreas into the intestine.

E

An enzyme that will digest proteins into amino acids is A) lipase. B) amylase. C) nuclease. D) maltase. E) carboxypeptidase.

E

Angiotensin II stimulates A) thirst only. B) vasoconstriction only. C) synthesis and release of aldosterone. D) thirst and vasoconstriction. E) thirst, vasoconstriction, and synthesis and release of aldosterone.

E

Bicarbonate secretion A) neutralizes acid entering from the stomach into the duodenum. B) is secreted by apical Cl--HCO3- exchanger. C) is not dependent on high levels of carbonic anhydrase to maintain bicarbonate production. D) is secreted by the acinar cells. E) neutralizes acid entering from the stomach into the duodenum and is secreted by apical Cl--HCO3- exchanger.

E

Dehydration can result from A) heat exhaustion. B) CCK. C) diabetes. D) gluconeogenesis. E) heat exhaustion and diabetes.

E

High carbon dioxide concentration in body fluids is called A) carbonation. B) hyperdioxia. C) hyperoxia. D) hypercarbia. E) hypercapnia.

E

Insulin A) only stimulates glycolysis. B) only stimulates lipogenolysis. C) only inhibits gluconeogenesis. D) stimulates glycolysis and lipogenolysis. E) stimulates glycolysis and inhibits gluconeogenesis

E

Ions directly regulated by the kidney include all EXCEPT which of the following? A) Na+ B) K+ C) Ca2+ D) HCO3- E) OH-

E

Match each product with the cell or region that secretes or contains it. A. enzymes B. HCl C. HCO3- D. mucus E. more than one of these pancreatic cells

E

Match the following structures with their functions. A. pancreas B. pylorus C. rectum D. small intestine E. stomach Chyme is released from here.

E

On a tour of African countries, Don contracts a bad case of traveler's diarrhea. Because he can't eat very much, his body starts to use energy sources other than carbohydrates. This would result in A) increased levels of urea in the blood. B) ketosis. C) a decreased blood pH. D) increased gluconeogenesis in the liver. E) All of these answers are correct.

E

Powerful contractions that occur a few times each day in the colon are called A) segmentation. B) tonic contractions. C) phasic contractions. D) peristalsis. E) mass movements.

E

Protective reflexes of the lungs include A) coughing. B) bronchoconstriction. C) bronchodilation. D) bronchodilation and coughing. E) coughing and bronchoconstriction.

E

Diagram the reactions and interactions of the renin-angiotensin system (RAS). Which condition is the primary stimulus for its activation?

Figure 20.10 diagrams these interactions. The primary stimulus is low blood pressure, detected in several ways.

Cary deliberately hyperventilates for several minutes before diving into a swimming pool. Shortly after he enters the water and begins swimming, he blacks out and almost drowns. What caused this to happen?

Hyperventilation causes a decrease in the alveolar PCO2, and more carbon dioxide is eliminated from the body than during normal breathing. The loss of large amounts of carbon dioxide upsets the body's normal drive for ventilation, and Cary does not feel the urge to breathe as he swims. As the exercising muscles use oxygen, a state of hypoxia develops. This results in insufficient amounts of oxygen reaching the brain, causing Cary to lose consciousness.

List the muscles of inspiration and expiration

Inspiration: diaphragm, external intercostals, scalenes, and sternocleidomastoids. Expiration: internal intercostals, abdominal wall muscles

Why does insulin deficiency lead to metabolic acidosis?

Insulin deficiency produces a fasted-state metabolism. The liver metabolizes fatty acids for its energy needs, producing ketones. The ketones enter the blood, then are absorbed by tissues and converted to acetyl CoA. Ketones themselves are strong acids, thus ketoacidosis results. Other tissues begin to produce lactic acid, due to their anaerobic state resulting from loss of access to glucose.

Distinguish between intrapulmonary and intrapleural pressure.

Intrapulmonary pressure is the pressure inside the alveoli. Intrapleural pressure is the pressure within the pleural cavity. Intrapleural pressure variation drives variation inside the alveoli, but is always lower than atmospheric pressure, where pressure inside the alveoli equilibrates with atmospheric pressure during the respiratory cycle.

How do kidneys alter urine concentration

Kidneys alter urine concentration by varying the amounts of water and sodium reabsorbed in the distal nephron

Sylvia is suffering from severe edema in her arms and legs. Her physician prescribes a diuretic (a substance that will increase the volume of urine produced). Why might this help to alleviate Sylvia's problem?

One simple answer is that a diuretic reduces the free fluid in the body. A more complex explanation is that increasing the volume of urine produced would decrease the total blood volume of the body. This in turn would lead to a decreased blood hydraulic pressure. Edema is frequently the result of hydraulic pressure of the blood exceeding the opposing forces at the capillaries in the affected area. Depending on the actual cause of the edema, decreasing the blood hydraulic pressure would decrease edema formation and possibly cause some of the fluid to move from the interstitial space back to the blood. Diuresis would also increase the concentration of the proteins in the plasma, contributing to the fluid's movement out of the tissues and into the blood.

Bronchioles and systemic arterioles dilate. A. PO2 increases B. PCO2 increases C. PO2 decreases D. PCO2 decreases

PCO2 increases

Arterioles: systemic dilate, pulmonary constrict A. PO2 increases B. PCO2 increases C. PO2 decreases D. PCO2 decreases

PO2 decreases

Arterioles: systemic constrict, pulmonary dilate. A. PO2 increases B. PCO2 increases C. PO2 decreases D. PCO2 decreases

PO2 increases

List the six types of epithelial cells associated with gastric glands. Briefly describe each one's role in the stomach.

Parietal cells secrete HCl and intrinsic factor; chief cells secrete pepsinogen and gastric lipase; D cells secrete somatostatin; ECL cells secrete histamine; G cells secrete gastrin; mucous cells secrete mucus and bicarbonate

Name the proenzymes secreted by the pancreas. Which one is involved in the activation of the other proenzymes? What are their active forms?

Proenzymes include: trypsinogen, chymotrypsinogen, procarboxypeptidase, procolipase, and prophospholipase. When it comes into contact with enteropeptidase in the brush border of the intestine, trypsinogen is converted to trypsin, which then activates the other proenzymes. The pathway can be found in Figure 21.14 in the chapter.

In ________, fluid accumulates in the interstitial spaces of the lungs, slowing gas exchange

Pulmonary edema

Where does carbohydrate digestion begin? Which enzyme is involved, and which reaction does it catalyze?

Salivary amylase is secreted into the mouth and digests large glucose polymers, like starch, into smaller glucose chains and the disaccharide maltose

What are the PO2 and PCO2 in the alveoli, artery, peripheral tissue, and veins? Explain why the PO2and PCO2change

See Figure 18.2 and the "Gas Exchange in the Lungs and Tissues" section of the chapter.

Compare and contrast the pulmonary pathologies that affect alveolar ventilation and gas exchange.

See Figure 18.3c in the chapter, which discusses emphysema, fibrotic lung disease, pulmonary edema, and asthma

Describe the different causes of hypoxia, and give specific examples of the associated conditions.

See Table 18.1 in the chapter.

How does decreased blood pressure affect the following: granular cells, glomerulus, cardiovascular control center, hypothalamus? Indicate if decreased blood pressure directly affects the organ or tissue above or acts through a reflex pathway. If it acts through a reflex pathway, name the reflex.

See Table 20.1 in the chapter

During the winter, Brad sleeps in a dorm room that lacks a humidifier for the heated air. In the mornings he notices that his nose is "stuffy," similar to when he has a cold, but after showering and drinking some water, the stuffiness disappears until the next morning. What might be the cause of Brad's nasal condition?

Since the air that Brad is breathing is not humidified (thus dry), large amounts of moisture are leaving the mucus to humidify the air that is being respired. This makes the mucus tacky and the cilia have difficulty moving. As more mucus is produced, it builds up, forming the nasal congestion in the morning. As Brad showers and drinks fluid, the moisture is replaced and the mucus loosens up and is moved along the proper route as usual. The reason this happens mostly at night is because Brad is probably not getting up frequently to drink water to replace what is being lost to humidify the air.

A package insert for a medication states that "this medicine is a beta receptor stimulant used to treat symptoms of asthma, emphysema and other breathing conditions. Possible side effects include fast heart rate, nervousness, tremors or nausea." Why would these symptoms be expected?

Stimulation of beta receptors activates the sympathetic division, overriding the parasympathetic division. Increased heart rate, nervousness, nausea, and tremors all accompany sympathetic stimulation.

What is surfactant? Why is it important?

Surfactant, made by the type II alveolar cells, reduces the surface tension in the fluid in the alveoli, thereby facilitating inflation and inhibiting collapse of the alveoli.

With what you have learned about pulmonary ventilation, how would you design an artificial respirator to keep patients with paralyzed respiratory muscles alive? How does artificial respiration by a machine compare to mouth-to-mouth respiration?

The artificial respirator needs to alternate the pressure it generates between slightly higher than atmospheric pressure and slightly lower than atmospheric pressure. These pressure fluctuations are what the respiratory system normally produces; thus they should be safe for the respiratory structures. The lungs of the patient will passively inflate and deflate in response, and gas exchange at the alveoli will occur. The principle is the same with mouth-to-mouth respiration.

You are a scientist who has been hired to write a screenplay for a popular TV series. The plot involves the discovery by a rogue botanist of a plant toxin that interferes with the function of the exchange pump responsible for the chloride shift. This scientist provides the toxin to bioterrorists. What should you write for the coroner to say about symptoms in the poisoning victims?

The chloride shift is the transport process that occurs in red blood cells and is necessary for normal carbon dioxide transport. In this process, a bicarbonate ion is exchanged for a chloride ion. As a result, the red blood cell loses bicarbonate, which carries a negative charge, but gains a chloride ion, thus maintaining its membrane potential. Losing the bicarbonate prevents the chemical reaction that produces bicarbonate from carbon dioxide and water from reaching equilibrium. Bicarbonate is the most important extracellular buffer in the body. Without the transporter function, bicarbonate will build up inside the red blood cell and will not be maintained in the plasma. With a reduction in plasma bicarbonate, acidosis will result. An increase in pulmonary ventilation is triggered by acidosis and can help reverse this process, but it may be unable to compensate fully for the lack of bicarbonate buffer. Chapter 20 covers some of the physiological consequences of acidosis.

Which single muscle contributes most to normal, resting inspiration?

The diaphragm

Premature babies frequently need to be put on a respirator to help them breathe. Why does this become a necessary treatment for many premature babies?

The lungs are one of the last organs to develop during pregnancy and the type II alveolar cells are particularly late in developing. Since the type II alveolar cells secrete surfactant, premature babies may not make enough surfactant to reduce the resistance to breathing and may need positive pressure oxygen to be given along with surfactant to help them breathe on their own.

"Water, water, everywhere, nor any drop to drink" is a phrase from the Rime of the Ancient Mariner by Samuel Taylor Coleridge. This poem describes an ocean ship unable to sail to land and running out of its supply of fresh water; sailors have long known that drinking seawater cannot prevent death from dehydration. What would result if the sailors attempted to alleviate their dehydration by drinking seawater? Justify your answer by describing kidney physiology. Why wouldn't reflexes, in response to dehydration, fully compensate? What does this illustrate about the force allowing kidneys to retain water under more normal conditions?

The osmolarity of seawater is higher than that of the kidney medulla, thus the osmotic gradient that normally allows net reabsorption of water does not exist. Seawater osmolarity is largely a result of permeant ions such as sodium and chloride, so ingested seawater raises plasma osmolarity when it is absorbed. When the kidneys form a filtrate of this high-osmolarity solution, the descending limb fails to reabsorb water because the kidney medulla has a lower osmolarity than the filtrate (opposite of normal), along its entire length, and in fact the medulla would lose water as it moved into the descending limb. While ions would be reabsorbed by the ascending limb as usual, it is not enough to drive sufficient water reabsorption. Reflexes such as secretion of water-preserving hormones are ineffective because, ultimately, water reabsorption depends only on osmosis, and the normal osmotic gradient has been disrupted.

) A person with cirrhosis of the liver has lower than normal levels of plasma proteins and a higher than normal GFR. Explain why a decrease in plasma protein concentration would cause an increase in GFR.

The primary driving force for GFR is blood pressure, opposed by fluid pressure in Bowman's capsule and osmotic pressure due to plasma proteins. If a person has fewer plasma proteins due to liver disease, the plasma will have a lower osmotic pressure. With less osmotic pressure opposing the GFR, GFR will increase

An industrious 10-year-old swimmer has attached an extension to his snorkel tube, so that he can sit on the bottom of the ocean for a longer period of time, watching the fish of the coral reef. What problems would you expect him to have? Assuming he is successful in breathing this way for a little while, what are some of the differences he will experience compared to normal breathing?

The resistance to air flow increases as a result of adding the extension to the snorkel tube. Assuming he has used an extension of sufficiently large diameter, he is in a shallow location where the total length isn't excessive, and he has the strength and endurance in his respiratory muscles, he may be able to breathe this way for a few seconds longer than he could have held his breath. He will probably notice that he is breathing more deeply and at a higher rate, to maintain ventilation against the higher resistance. After a few exchanges he will start to hypoventilate, despite his efforts to increase pulmonary ventilation, because the presence of dead airspace in the tube will result in decreasing PO2 in the alveoli. Dead airspace is a problem if the total volume of air in the tube is greater than the volume exchanged with each breath.

In some severe cases, a person suffering from stomach ulcers may have surgery to cut the branches of the vagus nerve that innervates the stomach. How would this help the problem

The vagus nerve carries neurons of the parasympathetic nervous system. These neurons control gastric secretions, notably the secretion of acid and enzymes. Severing these branches would eliminate neural stimulation from the central nervous system, thus eliminating the release of gastric fluids in response to anxiety and other higher-order stimuli when there is no food in the stomach. Normal digestive function would still occur, governed by various hormones and intramural neural reflexes.

Describe the problems that result in low arterial oxygen content

Three categories of problems are inadequacies in oxygen reaching alveoli, oxygen exchange between the alveoli and blood, and transport of oxygen in the blood.

________ is known as insulin-resistant diabetes

Type 2 diabetes

Compare and contrast the two types of diabetes mellitus

Type I diabetes mellitus is a condition of insulin deficiency due to pancreatic beta cell destruction. Type 2 diabetes mellitus is insulin-resistant, due to a variety of causes. Figure 22.20 in the chapter provides a detailed summary of the characteristics of type I diabetes

Ralph is taking SCUBA diving classes and is confused as to why he should not hold his breath under water while ascending—his instructor told him he must exhale continuously. What would you tell him?

When breathing the compressed air from a SCUBA tank, the lungs are virtually completely inflated. Problems would arise if he held his breath and began to ascend. On ascending, the decrease in pressure would cause the gas in his lungs to expand (Boyle's law). Since the lungs are already fully inflated, this would cause over-inflation and possible rupturing of the lung. If this occurred, air would leak from the lungs into the pleural cavity, resulting in a pneumothorax and a collapsed lung.

It is known that exercise is good for diabetics. Explain how GLUT4 transporters may be involved in this beneficial effect of exercise

When one exercises, skeletal muscles are utilized. Once they are active, they no longer require insulin to be able to take up glucose from the blood. This is due to the fact that exercise causes more GLUT4 transporters to be inserted into the membrane of the muscle cells. Thus, exercise is able to remove the excess glucose from the bloodstream of diabetics

Rachel, a nursing student, has been caring for burn patients. She notices that they consistently show elevated levels of potassium in their urine and wonders why. What would you tell her?

When tissues are burned, cells are destroyed and the contents of their cytoplasm leak into the interstitial fluid and then move into the plasma. Since potassium ion is normally found within the cell, damage to a large number of cells would release relatively large amounts of potassium into the blood. The elevated potassium levels would stimulate the cells of the adrenal cortex that produce aldosterone. The elevated levels of aldosterone would promote sodium retention and potassium secretion by the kidneys, thus accounting for the elevated levels of potassium in the patient's urine.

Eric has had trouble sleeping the last two nights and is currently experiencing heart burn which he attributes to the stress of being in finals week and eating too much pizza. His lab partner in Physiology class tells him he should take some diphenhydramine (Benadryl) before he goes to bed because that will help him sleep and his upset stomach. Is this a good suggestion or not?

While longstanding heartburn or insomnia may both be symptoms of more severe underlying conditions that require a visit to a health professional, his lab partner is correct. Diphenhydramine is an antihistamine that is found in many over-the-counter sleep medications. It has anticholinergic properties that could block vagus nerve stimulation preventing acid production.

Because of their smooth muscle component, the structures of the lower respiratory system that can most alter airway resistance are the ________.

bronchioles

Too little oxygen in cells is often accompanied by too much ________, which is called ________.

carbon dioxide, hypercapnia

________ is the enzyme that converts CO2 into bicarbonate ions

carbonic anhydrase

Metabolism is often divided into ________, energy-producing reactions, and ________, energy-utilizing reactions.

catabolism, anabolism

The ease with which the lungs stretch in response to changes in pressure is termed ________.

compliance

Eighty percent of the nephrons in a kidney are contained within the ________, but the other 20%, called the ________ nephrons, dip down into the ________.

cortex, juxtamedullary, medulla

When the inspiratory muscles relax, the rib cage returns to its original position as a result of ________.

elastic recoil

In the disease ________, many symptoms are due to destruction of elastic fibers in the lung

emphysema

Some have a congenital alpha-1 antitrypsin deficiency. If the job of alpha-1 antitrypsin is to inhibit trypsin and elastase, what condition are people with this genetic deficiency likely to develop?

emphysema

________ is characterized by a thickened alveolar membrane, slowing respiratory gas exchange.

fibrotic lung disease

The carotid and aortic bodies contain specialized ________ cells, which can increase ventilation in response to changes in PO2, PCO2, or pH.

glomus

Specialized ________ in the carotid and aortic bodies are activated by a decrease in PO2 and pH or an increase in PCO2. What do they trigger?

glomus. They trigger a reflex to increase ventilation

The pancreatic hormone that raises blood glucose concentration is ________.

glucagon

The process of synthesizing glucose from lipids, amino acids, or other carbohydrates is called ________.

gluconeogenesis

The excretion of glucose in the urine is called ________.

glucosuria/glycosuria

Lipids are broken down into ________, which feeds into glycolysis, and ________, which are metabolized to acetyl CoA

glycerol, fatty acids

The process of glycogen formation is known as ________.

glycogenesis

Generally, PO2 in arterial blood is ________ than PO2 in venous blood

higher

PCO2 tends to be ________ in tissues than in systemic capillaries

higher

A powerful bronchoconstrictor released by mast cells is ________.

histamine

An increase in the rate and depth of breathing is known as ________.

hyperventilation

Too little oxygen in cells is called

hypoxia

Generally, PCO2 in arterial blood is ________ than PCO2 in venous blood

lower

The ________ consist of light, spongy tissue whose volume is occupied mostly by air-filled spaces.

lungs

Diffusion rate is indirectly proportional to ________.

membrane thickness

The combination of type 2 diabetes, atherosclerosis, and high blood pressure is called ________.

metabolic syndrome

Match the term to its definition. A. metabolism B. catabolism C. anabolism the sum of all the body's chemical reactions

metabolism

The beating of the cilia of the respiratory passages in the direction of the pharynx forms a ________.

mucociliary escalator

Air flow in the respiratory system and blood flow in the cardiovascular system have many similarities—name them. How are they different?

1. Flow takes place from regions of higher pressure to regions of lower pressure. 2. A muscular pump creates pressure gradients. 3. Resistance to fluid flow is influenced primarily by the diameter of the tubes. The primary difference is that air is a compressible mixture of gases while blood is a non-compressible liquid.

Describe GFR autoregulation, and explain why it is important

1. The myogenic response is the ability of the vascular smooth muscle to constrict or dilate to keep pressure and flow constant, thereby keeping GFR constant. Vasoconstriction is more effective at this than vasodilation. 2. Tubuloglomerular feedback involves production of a paracrine, in response to increased GFR, which constricts the afferent arteriole to decrease GFR. Autoregulation helps protect the filtration barriers from high blood pressures that could damage them.

The cellular mechanisms for renal handling of H+ and HCO3- involve several membrane transporters; name three.

1. apical Na+-H+ exchanger 2. basolateral Na+- HCO3- symport 3. H+- ATPase 4. H+- K+- ATPase 5. Na+- NH4+ antiporter

What are the two mechanisms of bicarbonate reabsorption in the proximal tubule?

1. convert HCO3- into carbon dioxide, then back into HCO3- 2. through the metabolism of glutamine (see Fig. 20.17)

Diabetes mellitus produces many homeostatic imbalances, including acidosis. The pH imbalance is due to ketoacidosis, which results from excessive accumulation of by-products of fat metabolism, as the body cannot meet energy needs from carbohydrate metabolism. Sally is a teenaged diabetic who sometimes rebels by not taking her insulin. Her body is beginning to develop ketoacidosis as a result. Create a chart to indicate and explain how her blood pH, HCO3-, and PCO2 react, by indicating "increase," "decrease," or "no change." 1. ketoacidosis has just developed 2. respiratory compensation occurs 3. renal compensation occurs

1. pH decreases by definition, HCO3- decreases as the carbonic acid reaction shifts to the right, PCO2 is unchanged because the excess is expelled by the lungs due to the higher gradient. 2. pH increases and HCO3- decreases as exhaled CO2 drives the carbonic acid reaction to the right, and PCO2 decreases as it is exhaled. 3. pH increases as H+ is excreted, HCO3- increases as it is reabsorbed, and PCO2 increases as respiration returns to normal.

The amount of plasma that filters into the nephrons is approximately ________ of the total volume. A) 4/5 B) 1/5 C) 3/4 D) 1/2 E) 90%

B

The brain relies solely on ________ as its energy source. If it is deprived of this substrate, the cells soon die. A) fatty acids B) glucose C) amino acids D) insulin

B

Match each term to its definition. A. anabolism B. biochemical pathway C. catabolism reactions that result in breakdown of large molecules

C

Match the nutrient to its primary fate. A. carbohydrate B. protein C. fat storage

C

Most body water is located in A) plasma. B) interstitial fluid. C) cells. D) lumens of organs open to the outside.

C

An increase in PCO2 would cause A) the bronchioles to dilate and the systemic arterioles to dilate. B) the bronchioles to dilate and the systemic arterioles to constrict. C) the bronchioles to constrict and the systemic arterioles to dilate. D) the bronchioles to constrict and the systemic arterioles to constrict. E) None of the answers are correct.

A

Bile is A) secreted by hepatocytes only. B) manufactured by the gallbladder only. C) released into the stomach only. D) secreted by hepatocytes and manufactured by the gallbladder. E) secreted by hepatocytes, manufactured by the gallbladder, and released into the stomach.

A

Blood flow through the kidney includes a feature seen in only a few organs. What is it? A) portal system B) arterial shunts C) vascular sinuses D) veins containing highly oxygenated blood E) anastomoses

A

Chief cells secrete A) pepsinogen. B) gastrin. C) mucus. D) hydrochloric acid. E) intrinsic factor.

A

Decreased ECF volume causes A) sympathetic output from the cardiovascular control center to increase. B) parasympathetic output from the cardiovascular control center to increase. C) the force of ventricular contraction to decrease. D) arteriolar vasodilation. E) sympathetic output from the cardiovascular control center to increase and arteriolar vasodilation.

A

Drugs used to treat diabetes may A) stimulate beta-cell secretion of insulin. B) stimulate digestion and absorption of carbohydrates in the intestine. C) stimulate hepatic glucose output. D) decrease responsiveness of target tissue to insulin. E) None of these answers are correct

A

During normal expiration, A) elastic recoil of stretched muscles helps return the thorax to its resting volume. B) the internal intercostal muscles are required. C) the abdominal muscles become involved. D) elastic recoil of stretched muscles helps return the thorax to its resting volume and the internal intercostal muscles are required. E) elastic recoil of stretched muscles helps return the thorax to its resting volume, the internal intercostal muscles are required, and the abdominal muscles become involved.

A

During the absorptive state, A) the liver forms glycogen. B) adipocytes contribute fatty acids to the circulation. C) skeletal muscles break down glycogen. D) glucagon levels are elevated. E) All of these answers are correct.

A

Flow of air A) is directly proportional to a pressure gradient, and flow decreases as the resistance of the system increases. B) is directly proportional to the resistance, and flow decreases as the pressure of the system increases. C) is directly proportional to a pressure gradient, and flow increases as the resistance of the system increases. D) is directly proportional to the resistance, and flow increases as the resistance of the system increases. E) None of the answers are correct.

A

If blood flow through the afferent arterioles increases, A) stretch reflexes trigger vasoconstriction to reduce the flow. B) the smooth muscle in the vessel walls stretches to accommodate the increased flow. C) the stretch triggers further relaxation of the arteriolar wall, lessening blood pressure. D) the smooth muscle in the vessel walls stretches to accommodate the increased flow and the stretch triggers further relaxation of the arteriolar wall, lessening blood pressure.

A

In response to a rapid increase of organic acid in the body, you would expect to observe A) increased alveolar ventilation. B) decreased blood pressure. C) decreased heart rate. D) increased blood pH.

A

In response to the hormone cholecystokinin, the pancreas secretes a fluid that contains A) enzymes. B) bicarbonate. C) bile. D) only proteinases. E) only amylase.

A

In the digestive system, HCl is released by ________, whereas HCO3- is secreted primarily from the ________. A) parietal cells of the stomach, pancreas B) the pancreas, parietal cells of the stomach C) parietal cells of the stomach, liver D) the liver, parietal cells of the stomach

A

In the fasted state, which of the following statements is FALSE? A) Skeletal muscle will increase gluconeogenesis. B) Pyruvate and lactate are transported to liver to make glucose. C) Some amino acids will be deaminated. D) Adipose breaks down its store of triglycerides

A

In the lumen of the proximal tubule, Na+ concentration ________ the Na+ concentration inside the cells of the tubule wall. A) is much higher than B) is slightly higher than C) is about the same as D) is slightly lower than E) is much lower than

A

In the lungs, the A) blood flow rate is higher and the blood pressure is lower, respectively, than the blood flow rate and the blood pressure in other tissues. B) blood flow rate is higher and the blood pressure is higher, respectively, than the blood flow rate and the blood pressure in other tissues. C) blood flow rate is lower and the blood pressure is lower, respectively, than the blood flow rate and the blood pressure in other tissues. D) blood flow rate is lower and the blood pressure is higher, respectively, than the blood flow rate and the blood pressure in other tissues. E) blood flow rate and the blood pressure are the same as in other tissues.

A

Increasing the alveolar ventilation rate will A) increase the partial pressure of oxygen in the alveoli. B) decrease the rate of oxygen diffusion from the alveoli to the blood. C) increase the partial pressure of carbon dioxide in the alveoli. D) decrease the rate of carbon dioxide diffusion from the blood to the alveoli. E) have no effect on either the partial pressure or diffusion rate of gases.

A

Kidneys regulate A) water loss only. B) water gain only. C) both water loss and gain.

A

Kidneys respond relatively ________ to changes in blood volume. A) slowly B) quickly

A

Match each product with the cell or region that secretes or contains it. A. enzymes B. HCl C. HCO3- D. mucus E. more than one of these brush border

A

Match each term to its definition. A. anabolism B. biochemical pathway C. catabolism reactions that result in the synthesis of large molecules

A

Match the hormone with the correct statement. A. gastrin B. cholecystokinin C. secretin D. motilin E. gastric inhibitory peptide Secreted by cells in the stomach

A

Match the nutrient to its primary fate. A. carbohydrate B. protein C. fat used immediately for energy

A

Match the structure to its function. A. mouth B. stomach C. rectum D. small intestine E. large intestine Carbohydrate digestion begins here.

A

Normal removal of excess water in urine is known as A) diuresis. B) diuretics. C) osmotic diuresis. D) filtration.

A

Of the factors that influence diffusion of respiratory gases, the most variable and, therefore, important factor to consider is the A) concentration gradient. B) diffusion distance. C) membrane surface area. D) membrane thickness. E) electrical charge

A

Pre-diabetes is a condition that will likely become diabetes if eating and exercise habits are not altered. A) True B) False

A

Renal tubule cells in the kidney medulla are constantly exposed to high extracellular osmolarity. How do they maintain normal cell volume? A) They synthesize organic solutes as needed to match the osmolarity. B) They synthesize water molecules through increased metabolism to offset volume loss. C) They maintain a water-impermeable membrane. D) They add or remove aquaporins as needed.

A

The anatomical arrangement of the kidney that allows transfer of solutes from one blood vessel to another is called the A) countercurrent exchange system. B) portal system. C) capillaries. D) countercurrent heat exchanger.

A

The beta cells of the pancreas produce A) insulin. B) glucagon. C) renin. D) cortisol. E) digestive enzymes.

A

The characteristic yellow color of urine is attributed to the presence of A) urobilinogen. B) uric acid. C) urea. D) renin. E) bile

A

The enzyme renin is responsible for the activation of A) angiotensin I. B) cortisol. C) erythropoietin. D) atrial natriuretic peptide. E) adrenaline.

A

The enzyme that catalyzes the conversion of H2O and CO2 to H2CO3 is called A) carbonic anhydrase. B) bicarbonate ion. C) carbonic acid. D) renin.

A

The force for glomerular filtration is the A) blood pressure in the glomerular capillaries. B) osmotic pressure in the glomerular capillaries. C) fluid pressure produced by the displacement of the fluid in the lumen of the tubules. D) ATP-dependent processes in the nephron. E) None of the answers are correct.

A

The level of ketone bodies in the blood increases when high levels of ________ are being metabolized. A) fatty acids B) glucose C) proteins D) amino acids E) carbohydrates

A

The most potent stimulus for vasopressin release is A) plasma osmolarity. B) blood volume. C) blood pressure. D) low potassium.

A

Two hours before major surgery is to begin, the patient experiences "jitters," an elevated heart rate and blood pressure. These symptoms are the result of A) sympathetic activation. B) decreased levels of epinephrine in the blood. C) decreased activity of sympathetic centers in the hypothalamus. D) increased parasympathetic activity. E) All of these mechanisms.

A

Type I alveolar cells A) allow rapid diffusion of gases through their thin membranes. B) secrete a chemical known as surfactant. C) are phagocytic. D) allow rapid diffusion of gases through their thin membranes, secrete a chemical known as surfactant, and are phagocytic. E) None of the statements are true.

A

When blood glucose levels rise, as in the "fed" state, A) only insulin is released. B) only glucagon is released. C) only peripheral cells take up less glucose. D) only protein synthesis decreases. E) All of these answers are correct.

A

Which of the following features of the alveolar sacs allows for the ease of diffusion of gasses? A) They are made of a single layer of simple squamous epithelium. B) Type II alveolar cells secrete surfactant. C) Elastin fibers allow the alveoli to stretch thin enough for diffusion to occur. D) They are made of a single layer of simple squamous epithelium and elastin fibers allow the alveoli to stretch thin enough for diffusion to occur.

A

Which of the following statements about autoregulation is NOT true? A) Myogenic response is the intrinsic ability of vascular smooth muscle to respond to pressure changes. B) Myogenic response is a paracrine signaling mechanism. C) In tubuloglomerular feedback, stretch-sensitive ion channels open, resulting in depolarization of smooth muscle cells. D) In myogenic response, the macula densa cells send a paracrine message to the neighboring afferent arteriole.

A

Which of the following would make the oxygen-hemoglobin curve shift right? A) increased H+ concentration B) increased pH C) decreased temperature D) decreased CO2 E) None of the answers are correct

A

________ are tiny droplets of fatty acids, monoglycerides, and bile salts. A) Micelles B) Enterocyte membranes C) Chylomicrons D) Lacteals

A

________ interstitial osmolarity allows urine to be concentrated. A) High medullary B) Low medullary C) High cortex D) Low cortex

A

There is a mixture of gases in dry air, with an atmospheric pressure of 760 mm Hg. Calculate the partial pressure of each gas for the examples below: A. 20.7% oxygen, 78.2% nitrogen, 0.4% carbon dioxide B. 45% oxygen, 41% nitrogen, 3% carbon dioxide, 11% hydrogen C. 79% oxygen, 15% nitrogen, 5% carbon dioxide, 1% argon Answer: Partial pressure = Patm × % gas in atmosphere.

A. 157.32 mm Hg oxygen, 594.32 mm Hg nitrogen, 3.04 mm Hg carbon dioxide B. 342 mm Hg oxygen, 311.6 mm Hg nitrogen, 22.8 mm Hg carbon dioxide, 83.6 mm Hg hydrogen C. 600.4 mm Hg oxygen, 114 mm Hg nitrogen, 38 mm Hg carbon dioxide, 7.6 mm Hg argon

You were the top student in your physiology class last semester. For this reason, your professor has asked that you prepare some lectures for her physiology class this semester. Specifically, she would like you to discuss the similarities and differences between the cardiovascular and respiratory systems, in terms of pressure gradients and fluid flow. A. Explain how you will describe the role of the following structures: the pump and the tubes. B. Explain how you will describe the importance of an open vs. closed system and the relevant differences between liquids and gases. C. What is fundamentally different about the respiratory pump compared to the cardiac pump, and why does this difference exist?

A. In both systems, fluids flow down a pressure gradient, within different-sized tubes of variable resistance; the pressure gradient is generated by the action of a muscular pump. In the cardiovascular system, the tubes vary from elastic arteries that minimize pressure extremes and fluctuations, muscular arteries and arterioles whose diameter is changeable to regulate flow and that account for most of the resistance, finally to the large number of tiny capillaries in parallel, with veins to conduct the blood back to the pump. In the respiratory system, the larger tubes are rigid and account for most of the resistance, and lead to a large number of tiny tubes in parallel whose diameter is adjusted to regulate flow. B. In the closed cardiovascular system, the highest pressure is generated within the left ventricle, and an incompressible liquid flows in a continuous fashion. High pressure is created when the ventricle contracts, squeezing the blood it contains; low pressure results when the ventricle relaxes. In the open respiratory system, the highest pressure during normal breathing is generated when the respiratory muscles relax, decreasing the volume of the alveoli as air flows out; low pressure results when the muscles contract. Air is compressible, thus Boyle's law of inverse relationship between volume and pressure is important. The flow of air is intermittent, flowing into the lungs then stopping, and flowing out of the lungs then stopping again. C. The driving pressure for fluid flow in the cardiovascular system is created directly by contraction of the heart chamber, and depends upon the total peripheral resistance. The driving pressure for fluid flow in the respiratory system is created indirectly by contraction of respiratory muscles, which produces a volume increase that creates a pressure decrease relative to atmospheric pressure. The compressibility of air and the incompressibility of blood, as well as the fact that the respiratory system is open and thus dependent on atmospheric pressure, while the cardiovascular system is closed and thus wholly responsible for pressure, explains these differences.

What would be the nutritional consequence of excessive antacid use

Antacids make the stomach pH higher than normal, which will interfere with protein digestion because the enzymes would not be as efficient.

Fred suffers from chronic emphysema. Blood tests show that his pH is normal but his bicarbonate levels are elevated significantly. How can this be?

As long as the ratio of bicarbonate ion to carbonic acid is 20:1, the pH of body fluids will remain normal. Since Fred's condition is chronic (long term) his body has compensated for the excess carbonic acid (the result of hypercapnea due to poor ventilation) by increasing the amount of bicarbonate to match the elevated level of acid. This process involves the kidneys where some of the excess carbon dioxide is converted into carbonic acid and the carbonic acid is allowed to dissociate. The hydrogen ions are secreted and the newly formed bicarbonate is conserved to maintain a proper buffering capacity

Carbon dioxide is more soluble in water than oxygen. To get the same amount of oxygen to dissolve in plasma as carbon dioxide, you would have to A) decrease the temperature of the plasma. B) increase the partial pressure of oxygen. C) decrease the partial pressure of nitrogen. D) increase the rate of plasma flow through the lungs. E) decrease the alveolar ventilation rate.

B

Decreased levels of bile salts in the bile would interfere with digestion of A) protein. B) fat. C) carbohydrates. D) nucleic acids. E) vitamins and minerals

B

Diarrhea often accompanies intestinal infections. Why? A) The immune system increases the production of enzymes for added protection. B) Bacterial toxins enhance the secretion of Cl- from the cells, which causes water movement into the intestine. C) Dehydration of the body will kill the bacteria causing the infection. D) Loss of electrolytes will kill bacteria.

B

Digestion is essentially completed in the A) stomach. B) small intestine. C) large intestine. D) anus.

B

Mr. Gregory comes to the doctor with high blood pressure. Tests show that he also has elevated levels of renin in his blood and atherosclerotic plaques that have nearly blocked blood flow through his renal arteries. Mr. Gregory is puzzled. Explain to him how decreased blood flow in his renal arteries could cause renin secretion to increase. Map the pathways through which elevated renin causes high blood pressure for Mr. Gregory.

Atherosclerotic plaques block blood flow, which decreases GFR and decreases pressure in the afferent arteriole. These are both stimuli for renin release. Renin secretion starts a cascade that produces angiotensin II, a vasoconstrictor. Vasoconstriction increases blood pressure, and the medullary control center responds to Ag II by also increasing ADH, aldosterone secretion, and thirst, collectively increasing blood pressure even further.

A student in your lab volunteers to enter a hypoxic breathing chamber for 10 minutes, and his alveolar PO2 drops to 50 mm Hg. What other change would occur? A) decrease in arterial pH B) decrease in arterial PCO2 C) decrease in pH of cerebrospinal fluid D) increase in alveolar PCO2 E) hypoventilation

B

Air moves out of the lungs because A) the gas pressure in the lungs is less than outside pressure. B) the volume of the lungs decreases with expiration. C) the thorax is muscular. D) contraction of the diaphragm increases the volume of the pleural cavity. E) All of the answers are correct.

B

Aldosterone A) is secreted in response to elevated levels of sodium in the blood. B) promotes sodium retention in the kidneys. C) helps decrease blood volume. D) increases the concentration of sodium in urine. E) functions in pH regulation.

B

Alveolar ventilation refers to the A) movement of air into and out of the lungs. B) movement of air into and out of the alveoli. C) movement of dissolved gases from the alveoli to the blood. D) movement of dissolved gases from the blood to the alveoli. E) utilization of oxygen by alveolar cells to support metabolism.

B

An enzyme that digests fats is A) hydrolase. B) lipase. C) lyase. D) ligase. E) kinase.

B

An increase in the level of carbon dioxide in the blood will A) decrease the rate of breathing. B) increase the rate of breathing. C) decrease pulmonary ventilation. D) decrease the alveolar ventilation rate. E) increase the pH of arterial blood.

B

An obstruction in a glomerulus would affect the flow of blood into the A) renal artery. B) efferent arteriole. C) afferent arteriole. D) renal vein.

B

Bile is produced in the ________ and stored in the ________. A) gallbladder, liver B) liver, gallbladder C) pancreas, hepatocytes D) hepatocytes, pancreas

B

Bile salts aid in the digestion of fats by ________ large fat droplets. A) generating B) emulsifying C) absorbing D) digesting fats within

B

Both insulin and glucagon are peptide hormones that target liver cells. The responses of the target cells to these two hormones are exactly the opposite of each other. This information implies that A) one hormone binds to a receptor on the cell membrane and the other to an intracellular receptor. B) each of the two hormones uses a different second messenger. C) both hormones interact with receptors at the cell nucleus. D) one of the hormones does not interact with a membrane receptor.

B

Breathing that involves active inspiratory and expiratory movements is called A) eupnea. B) hyperpnea. C) diaphragmatic breathing. D) costal breathing. E) shallow breathing.

B

During starvation, A) carbohydrate utilization increases. B) gluconeogenesis accelerates. C) there is a decline in circulating ketone bodies. D) structural proteins cannot be used as a potential energy source. E) All of these answers are correct.

B

During the fasting state, the energy stores of the ________ become the major source of glucose for the whole body. A) brain B) liver C) muscles D) pancreas E) adipose tissues

B

Excess potassium ions are eliminated from the body by the A) sweat glands. B) kidneys. C) liver. D) digestive system. E) spleen.

B

For maximum efficiency in loading oxygen at the lungs, A) the pH should be slightly acidic. B) the temperature should be slightly lower than normal body temperature. C) the PO2 should be about 70 mm. D) DPG levels in the red blood cells should be high. E) All of the answers are correct.

B

Glucose and amino acids are reabsorbed by A) diffusion. B) symport with sodium. C) cotransport. D) countertransport.

B

If the partial pressure of oxygen in both air and water is 100 mm Hg, then the concentration of the oxygen is the same in the air and water. A) True B) False

B

In a condition known as pleurisy, there is excess fluid in the pleural space. How would you expect this to affect the process of pulmonary ventilation? A) Ventilation would require less energy. B) Breathing would be labored and difficult. C) It would be easier to expand the lungs on inspiration. D) More air would be forced out during expiration. E) Tidal volume would increase.

B

In response to the hormone secretin, the pancreas secretes a fluid that contains A) enzymes. B) bicarbonate. C) bile. D) only proteases. E) only amylase.

B

In type 2 diabetes, insulin levels are frequently normal, yet the target cells are less sensitive to the effects of insulin. This suggests that the target cells A) are impermeable to insulin. B) may have a defect in their signal transduction pathway. C) cannot convert insulin to an active form. D) have adequate internal supplies of glucose. E) None of these answers are correct.

B

Maltose is broken down by maltase into two molecules of A) galactose. B) glucose. C) starch. D) amylase.

B

Match each product with the cell or region that secretes or contains it. A. enzymes B. HCl C. HCO3- D. mucus E. more than one of these parietal cells

B

Match each term to its definition. A. anabolism B. biochemical pathway C. catabolism series of interconnected chemical reactions

B

Match the factor with its effect on the affinity of hemoglobin for oxygen. A. Increase B. Decrease increased 2,3-DPG

B

Match the factor with its effect on the affinity of hemoglobin for oxygen. A. Increase B. Decrease increased pCO2

B

Match the factor with its effect on the affinity of hemoglobin for oxygen. A. Increase B. Decrease increased temperature

B

Match the hormone with the correct statement. A. gastrin B. cholecystokinin C. secretin D. motilin E. gastric inhibitory peptide inhibits gastric emptying

B

Match the hormone with the correct statement. A. gastrin B. cholecystokinin C. secretin D. motilin E. gastric inhibitory peptide stimulates bile release

B

Match the nutrient to its primary fate. A. carbohydrate B. protein C. fat synthesis of tissues

B

Match the structure to its function. A. mouth B. stomach C. rectum D. small intestine E. large intestine Fat digestion begins here.

B

Match the structure to its function. A. mouth B. stomach C. rectum D. small intestine E. large intestine Protein digestion begins here.

B

Match the term to its definition. A. metabolism B. catabolism C. anabolism large molecules broken into smaller ones

B

Measurements in a nephron reveal a glomerular hydraulic pressure of 69 mm Hg, and a fluid pressure in the Bowman's capsule of 15 mm Hg. Assuming that the plasma osmotic pressure is 30 mm Hg, and that essentially no plasma proteins are filtered by the glomerulus, what is the net glomerular filtration pressure in this case? A) -6 mm Hg B) 24 mm Hg C) 54 mm Hg D) 84 mm Hg E) 114 mm Hg

B

Most absorbed nutrients first enter the blood of the ________ system. A) lymphatic B) hepatic portal C) arterial D) immune

B

Osmoreceptors depolarize after they ________ in response to ________ plasma osmolarity. A) shrink, decreased B) shrink, increased C) swell, decreased D) swell, increased

B

Place the following blood vessels that carry blood to and within the kidney in the order in which blood passes through them. 1. afferent arteriole 2. efferent arteriole 3. glomerulus 4. peritubular capillary A) 4, 2, 3, 1 B) 1, 3, 2, 4 C) 4, 3, 2, 1 D) 1, 2, 3, 4 E) 3, 4, 2, 1

B

Specific responses to changes in body temperature are regulated by the A) thermoreceptors. B) hypothalamus. C) medulla oblongata. D) skin. E) cardiac output.

B

The Atkins and South Beach diets are considered ketogenic because A) Type I diabetics use them. B) they cause the body to burn calories from non-carbohydrate sources. C) they shift one's metabolism to increased levels of glycolysis. D) they have the potential to increase the body's pH. E) they require people to eat large quantities of ketones

B

The RAS pathway begins with secretion of A) angiotensin converting enzyme. B) renin. C) angiotensinogen. D) aldosterone. E) vasopressin.

B

The ________ cells of the distal nephron are interspersed among the principal cells and contribute to acid-base regulation. A) endothelial B) intercalated C) endocrine D) granular

B

The alpha cells of the pancreas produce A) insulin. B) glucagon. C) renin. D) cortisol. E) digestive enzymes.

B

The gastric phase of gastric secretion is triggered by the A) sight, thought, or smell of food. B) entry of food into the stomach. C) entry of chyme into the small intestine. D) entry of chyme into the large intestine. E) release of cholecystokinin and secretin by the small intestine.

B

The partial pressure of carbon dioxide in the cells of peripheral tissues is approximately ________ mm Hg. A) 40 B) 45 C) 50 D) 70 E) 100

B

The primary function of the proximal tubule is A) filtration. B) reabsorption of ions, organic molecules, and water. C) secretion of acids and ammonia. D) secretion of drugs. E) adjusting the urine volume.

B

The primary route for ion loss from the body is the ________ system. A) respiratory B) urinary C) digestive D) integumentary E) cardiovascular

B

The primary route for water loss from the body is the ________ system. A) respiratory B) urinary C) digestive D) integumentary E) cardiovascular

B

Type II alveolar cells A) allow rapid diffusion of gases through their thin membranes. B) secrete a chemical known as surfactant. C) are phagocytic. D) allow rapid diffusion of gases through their thin membranes, secrete a chemical known as surfactant, and are phagocytic. E) None of the statements are true.

B

Vitamin ________ must be complexed with a protein called ________ to be absorbed from the small intestine. A) D, somatomedins B) B12, intrinsic factor C) K, hydrogen sulfide D) A, Olestra

B

Vomiting and diarrhea are similar since both A) use normal GI motility to move substances. B) work to rid the body of damaging agents. C) are stimulated by the CNS. D) are used to prepare patients for surgery.

B

When baroreceptors in the carotid and aortic bodies register increased blood pressure, this results in A) secretion of vasopressin. B) inhibition of vasopressin secretion. C) increased glomerular filtration. D) decreased urine production. E) increased thirst.

B

When blood glucose levels fall, A) only insulin is released. B) only glucagon is released. C) only peripheral cells take up less glucose. D) only protein synthesis decreases. E) All of these answers are correct.

B

When the pH of body fluids begins to fall, proteins will A) become more active. B) lose three-dimensional structure. C) fold into tertiary structures. D) not be affected.

B

When the pH rises above 7.42, a state of ________ exists. A) acidosis B) alkalosis C) equilibrium D) homeostasis

B

When venous return is increased, stretch receptors in the atria of the heart are activated. This results in A) secretion of vasopressin. B) inhibition of vasopressin secretion. C) increased glomerular filtration. D) decreased urine production. E) increased thirst.

B

Which effect would a decrease in pH have on the amount of potassium ion in the urine? A) increase B) decrease C) no effect

B

Which is NOT produced in the body for the purpose of storing extra calories? A) fat B) protein C) carbohydrate D) All of these are produced in the body for that purpose.

B

Which of the following events does NOT occur when you swallow? A) Respiration is inhibited. B) The upper esophageal sphincter closes. C) The epiglottis closes. D) The lower esophageal sphincter relaxes.

B

Which of the following is NOT true about angiotensin II? A) increases cardiac output B) activates parasympathetic output C) is a potent vasoconstrictor D) elevates blood pressure E) stimulates thirst

B

Which of the following is an accessory organ of digestion? A) stomach B) pancreas C) spleen D) colon E) esophagus

B

Which structure is NOT part of the blood circulation through the kidney? A) vasa recta B) loop of Henle C) glomerulus D) renal corpuscle

B

Why do patients taking loop diuretics need to take supplemental potassium? A) They cause active secretion of potassium in the loop of Henle. B) They inhibit the reabsorption of potassium as well as sodium in the loop of Henle. C) They inhibit intestinal absorption of potassium. D) They cause active reabsorption of potassium in the distal convoluted tubule.

B

decreased surface area for gas exchange A. fibrotic lung disease B. emphysema C. asthma D. pulmonary edema

B

destruction of alveoli A. fibrotic lung disease B. emphysema C. asthma D. pulmonary edema

B

increases respiratory rate and/or volume without increased metabolism A. hyperpnea B. hyperventilation C. tachypnea D. dyspnea E. apnea

B

tabolism is a term that describes A) all work done by a living organism. B) all chemical reactions that take place within an organism. C) only chemical reactions that release ATP from living cells. D) the energy released from chemical bonds in living cells. E) the extraction of nutrients from biomolecules

B

Compare and contrast carbon monoxide (CO) poisoning, in which CO displaces oxygen from hemoglobin, and metabolic poisoning such as by cyanide.

Both types of poisoning interfere with oxygen-dependent metabolism and thus can be fatal. CO prevents oxygen loading at the lungs and thus produces hypoxia. Metabolic poisons exert their effects on the chemical reactions that consume oxygen to produce ATP, and thus have no effect on PO2.

The nephron begins with a hollow, ball-like structure called ________.

Bowman's capsule

A harmful substance that the liver produces when metabolizing fatty acids is A) ammonia. B) urea. C) ketone bodies. D) rancid fatty acids. E) beta units.

C

After processing in the stomach, the gastric contents are referred to as A) feces. B) food. C) chyme. D) filtrate.

C

All of the following will normally be found in the filtrate EXCEPT A) glucose. B) potassium. C) erythrocytes. D) urobilinogen.

C

Cell volume (and therefore cell function) in most cells is dependent upon careful regulation of A) volume of extracellular fluid. B) blood pressure. C) osmolarity of extracellular fluid. D) permeability of cell membranes. E) resting membrane potential.

C

Chronic inhalation of fine particles that reach the alveoli leads to ________ lung disease. A) obstructive B) restrictive C) fibrotic D) compliant E) congestive

C

Cysts on the kidney can press upon nephrons, raising the pressure inside the nephrons. How will this affect glomerular filtration rate and blood pressure? A) GFR increases and blood pressure increases B) GFR increases and blood pressure decreases C) GFR decreases and blood pressure increases D) GFR decreases and blood pressure decreases

C

Damage to the renal medulla would interfere first with the functioning of the A) Bowman's capsule. B) distal tubule. C) collecting ducts. D) proximal tubule. E) glomerulus.

C

Dehydration may cause some ions to become concentrated. If a person was suffering from severe hyperkalemia, you would expect A) the potassium ion concentration of the interstitial fluid to be less than normal. B) the membrane potential of nerves and muscles to be more negative. C) abnormal cardiac rhythms. D) muscle weakness and increased strength of twitch contractions. E) All of the answers are correct.

C

Functions of the kidneys include all but one of the following. Identify the exception. A) regulation of extracellular fluid volume B) maintenance of ion balance in body fluids C) regulation of blood protein levels D) regulation of blood osmolarity E) homeostatic regulation of blood pH

C

Functions of the large intestine include A) chemical digestion of chyme. B) temporary food storage. C) absorption of water and compaction of feces. D) absorption of most products of digestion. E) All of these answers are correct.

C

Gluconeogenesis refers to A) converting glucose to glycogen storage. B) removing glucose from storage as glycogen. C) creating glucose from glycerol, amino acids, or lactate. D) converting glucose to storage as adipose tissue. E) removing fatty acids from adipose storage.

C

Harry suffers from cystic fibrosis and frequently has periods where he can hardly breathe. The problem is the result of A) inflammation of the bronchi. B) constriction of the trachea. C) thick secretions that exceed the ability of the mucus elevator to transport them. D) laryngospasms that occur in response to a toxic substance produced by the epithelial cells. E) collapse of one or both lungs.

C

If sodium increases in the ECF, water will move from A) cells to the ECF, and cells will swell. B) the ECF to cells, and cells will swell. C) cells to the ECF, and cells will shrink. D) the ECF to cells, and cells will shrink.

C

In normal kidneys, blood cells and plasma proteins are A) filtered then reabsorbed. B) secreted then reabsorbed. C) not filtered. D) filtered and secreted.

C

In type I diabetes, a hyperglycemic hyperosmotic state may occur. Which of the following best describes this state? A) There are low levels of vasopressin (ADH). B) There is decreased water intake. C) Plasma glucose and blood osmolarity levels are above normal. D) ATP production is increased due to the increased levels of glucose. E) Blood osmolarity is below normal levels due to elevated glucose.

C

Insulin secretion A) is stimulated by sympathetic neurons. B) decreases in response to elevated amino acid concentrations. C) is stimulated by parasympathetic neurons. D) is inhibited by GLP-1. E) None of these answers are correct.

C

Joe is playing in an intramural football game when he is tackled so hard that he breaks a rib. He can actually feel a piece of the rib sticking through the skin, and he is having a difficult time breathing. Joe probably is suffering from A) a collapsed trachea. B) an obstruction in the bronchi. C) a pneumothorax. D) decreased surfactant production. E) a bruised diaphragm

C

Most of the carbon dioxide in the blood is transported as A) solute dissolved in the plasma. B) carbaminohemoglobin. C) bicarbonate ions. D) solute dissolved in the cytoplasm of red blood cells. E) carbonic acid.

C

Most products of fat digestion are absorbed by A) capillaries. B) veins. C) lymphatic vessels. D) arterioles.

C

Nearly 90% of our dietary calories from fat are in the form of A) steroids. B) phospholipids. C) triglycerides. D) cholesterol. E) fat-soluble vitamins.

C

Nutrient absorption occurs primarily in the A) stomach. B) liver. C) small intestine. D) large intestine. E) stomach and small intestine.

C

One substance has no membrane transporters to move it but can diffuse freely through open leak channels if there is a concentration gradient. Initially, this substance's concentrations in the filtrate and extracellular fluid are equal. Later, however, the active transport of Na+ and other solutes creates a gradient by removing water from the lumen of the tubule where it is located. What substance is this? A) glucose B) calcium C) urea D) glucose and calcium E) glucose, calcium, and urea

C

The liver and skeletal muscles store glucose as ________ for a ready energy source. A) lipids B) glucose C) glycogen D) urea E) ketone bodies

C

The lung pathology most likely to result from certain kinds of heart disease is A) emphysema. B) asthma. C) pulmonary edema. D) fibrotic lung disease. E) lung cancer.

C

The primary role of the carbonic acid-bicarbonate buffer system is to A) buffer stomach acid. B) buffer carbonic acid formed by carbon dioxide. C) prevent pH changes caused by organic and fixed acids. D) buffer the urine. E) increase the amount of carbonic acid during ventilation.

C

The process by which dissolved gases are exchanged between the blood and interstitial fluids is A) pulmonary ventilation. B) external respiration. C) diffusion. D) cellular respiration. E) breathing.

C

Urea is A) actively secreted in the distal tubule. B) actively reabsorbed in the proximal tubule. C) passively reabsorbed in the proximal tubule. D) completely eliminated in the urine. E) actively transported into the filtrate by the cells of the collecting duct.

C

Urine is carried to the urinary bladder by A) blood vessels. B) lymphatics. C) the ureters. D) the urethra. E) All of the answers are correct.

C

Urine is produced by the A) gallbladder. B) urinary bladder. C) kidney. D) ureter. E) urethra.

C

When a body is dehydrated, water in the urinary bladder A) can be returned to the circulation directly. B) can be returned to the circulation after moving back into the kidneys. C) will still be expelled from the body in the urine.

C

When amino acids are metabolized for energy, the nitrogen is converted to urea and then is excreted from the body by the A) liver. B) skin. C) kidneys. D) sweat glands. E) spleen.

C

When blood levels of glucose, amino acids, and insulin are high, and glycogenesis is occurring in the liver, the body is in the A) fasting state. B) postabsorptive state. C) absorptive state. D) stress state. E) bulimic state.

C

When the diaphragm and external intercostal muscles contract, A) expiration occurs. B) intrapulmonary pressure increases. C) intrapleural pressure decreases. D) the volume of the lungs decreases. E) All of the answers are correct.

C

When the pH of the extracellular fluid declines, the kidneys A) excrete more sodium ions. B) excrete more bicarbonate ions. C) reabsorb more potassium ions. D) reabsorb more hydrogen ions. E) reabsorb less water.

C

Which of the following kidney processes is always active and always requires energy to occur? A) filtration B) reabsorption C) secretion D) excretion

C

rapid breathing A. hyperpnea B. hyperventilation C. tachypnea D. dyspnea E. apnea

C

Write the chemical equation catalyzed by the enzyme carbonic anhydrase. Suppose the concentration of H+ is increased by an outside force in a solution that had been at equilibrium. According to the law of mass action, what must happen to the CO2 concentration to reestablish equilibrium after this disturbance? What must happen to the concentration of bicarbonate?

CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3- Carbon dioxide concentration will increase as the reaction is shifted to the left. Bicarbonate concentration will decrease.

Cholesterol is absorbed without being digested into smaller pieces. How does this compare to absorption of carbohydrates and proteins? Which characteristic of cholesterol suggests it would be transported by simple diffusion? What is the evidence that transport proteins are involved in cholesterol absorption? Does this discovery rule out transport by simple diffusion?

Carbohydrates are digested to monosaccharides before they are absorbed. Proteins are absorbed as amino acids, di- or tripeptides, or even oligopeptides. As a lipid, cholesterol can dissolve in the phospholipid bilayer and therefore cross membranes by simple diffusion. The drug ezetimibe inhibits cholesterol absorption, suggesting there must be a membrane transporter. This discovery does not rule out additional transport of cholesterol by simple diffusion, but does suggest there is a significant amount of transport dependent upon a transport molecule.

Distinguish between cellular and external respiration

Cellular respiration refers to the intracellular reactions that consume oxygen and produce ATP. External respiration refers to the exchange of gases between the environment and lungs, lungs and blood, blood and cells, and the transport of those gases.

Blocking afferent action potentials from the chemoreceptors in the carotid and aortic bodies would interfere with the brain's ability to regulate breathing in response to all EXCEPT which of the following? A) changes in PCO2 B) changes in PO2 C) changes in pH due to carbon dioxide levels D) changes in blood pressure

D

Chronic hypoxia A) increases 2,3-DPG production in blood. B) shifts the HbO2 dissociation curve to the left. C) can be caused by anemia. D) increases 2,3-DPG production in blood and can result from anemia. E) All of the answers are correct.

D

Contents in the peritubular capillaries are actively transported into proximal and distal convoluted tubules in a process known as A) excretion. B) filtration. C) reabsorption. D) secretion.

D

Damage to the type II cells of the lungs would contribute to A) a thickening of the respiratory membrane. B) an increased rate of gas exchange. C) alveolar rupture. D) alveolar collapse. E) decreased surface tension in the water lining the alveoli.

D

Glucagon A) only stimulates gluconeogenesis. B) primarily targets the liver. C) primarily targets skeletal muscle. D) stimulates gluconeogenesis and primarily targets the liver. E) stimulates gluconeogenesis and primarily targets skeletal muscle.

D

Granular cells secrete A) angiotensinogen. B) angiotensin I. C) aldosterone. D) renin. E) angiotensin converting enzyme.

D

Identify the answer choice that lists the GI functions that are most closely regulated by the body. A) absorption and motility B) digestion and motility C) secretion and digestion D) motility and secretion E) motility, secretion, and digestion

D

If you were in a desert without a food source, which nutrient would you like to have stored in your body in a large amount? A) protein B) glycogen C) calcium D) fat E) vitamin B6

D

In a normal kidney, which of the following conditions would cause an increase in the glomerular filtration rate (GFR)? A) constriction of the afferent arteriole B) a decrease in the hydraulic pressure of the glomerulus C) an increase in the capsular hydraulic pressure D) a decrease in the concentration of plasma proteins in the blood E) a decrease in the net glomerular filtration pressure

D

Jill lives in St. Louis, which is close to sea level. She decides to spend a month of her summer vacation working in the mountains outside of Denver. After a week in the mountains, what kinds of changes would you expect to see as Jill adapts to the higher altitude? A) decreased hematocrit B) decreased blood pressure C) decreased alveolar ventilation rate D) decreased PO2 in the alveoli E) All of the answers are correct.

D

Match each product with the cell or region that secretes or contains it. A. enzymes B. HCl C. HCO3- D. mucus E. more than one of these goblet cells

D

Match the following structures with their functions. A. pancreas B. pylorus C. rectum D. small intestine E. stomach organ where most digestion occurs

D

Match the structure to its function. A. mouth B. stomach C. rectum D. small intestine E. large intestine Carbohydrate digestion is completed here.

D

Match the structure to its function. A. mouth B. stomach C. rectum D. small intestine E. large intestine Fat digestion is completed here.

D

Match the structure to its function. A. mouth B. stomach C. rectum D. small intestine E. large intestine Protein digestion is completed here.

D

Mucus functions in A) protection only. B) lubrication only. C) enzyme activation only. D) protection and lubrication. E) protection, lubrication, and enzyme activation.

D

Paracrine feedback from the ________ in the distal tubule to the granular cells stimulates release of ________. A) sympathetic neurons, epinephrine B) granular cells, renin C) liver, angiotensinogen D) macula densa, renin

D

Place the following structures of the respiratory tree in the order in which air passes through them. 1. secondary bronchi 2. bronchioles 3. primary bronchi 4. alveoli 5. terminal bronchioles A) 4, 1, 2, 3, 5 B) 1, 3, 5, 2, 4 C) 3, 1, 5, 2, 4 D) 3, 1, 2, 5, 4 E) 1, 3, 2, 5, 4

D

Prolonged vomiting of the stomach's contents can result in A) respiratory acidosis. B) respiratory alkalosis. C) metabolic acidosis. D) metabolic alkalosis. E) None of the answers are correct.

D

Stimuli for the activation of the RAS pathway include A) low blood pressure in arterioles in the nephron only. B) a decrease in fluid flow through the distal tubule only. C) high blood pressure in the renal artery only. D) low blood pressure in arterioles in the nephron and a decrease in fluid flow through the distal tubule. E) low blood pressure in arterioles in the nephron, a decrease in fluid flow through the distal tubule, and high blood pressure in the renal artery.

D

Surfactant A) protects the surface of the lungs. B) phagocytizes small particulate matter. C) replaces mucus in the alveoli. D) helps prevent the alveoli from collapsing. E) is not found in healthy lung tissue.

D

Symptoms of low plasma pH may include A) CNS depression only. B) confusion and disorientation only. C) numbness, tingling, or muscle twitches only. D) CNS depression and confusion and disorientation. E) CNS depression; confusion and disorientation; and numbness, tingling, or muscle twitches.

D

The ________ is a significant site of absorption of water and electrolytes, but NOT of nutrients. A) mouth B) stomach C) small intestine D) large intestine E) None of the answers are correct.

D

The chloride shift occurs when A) hydrogen ions leave the red blood cells. B) hydrogen ions enter the red blood cells. C) bicarbonate ions enter the red blood cells. D) bicarbonate ions leave the red blood cells. E) carbonic acid is formed.

D

The common passageway shared by the respiratory and digestive systems is the A) larynx. B) glottis. C) vestibule. D) pharynx. E) esophagus.

D

The enzyme that digests starch into disaccharides is A) lactase. B) maltase. C) sucrose. D) amylase.

D

The exocrine portion of the pancreas consists of lobules called ________, which secrete ________. A) acini, hormones B) islets, digestive enzymes C) islets, hormones D) acini, digestive enzymes

D

The hormone that regulates water reabsorption by the kidneys A) decreases water permeability throughout the kidney tubules. B) increases water permeability throughout the kidney tubules. C) only decreases water permeability in certain portions of the kidney tubules. D) only increases water permeability in certain portions of the kidney tubules.

D

The most important factor affecting the pH of plasma is the concentration of A) lactic acid. B) ketone bodies. C) organic acids. D) carbon dioxide. E) hydrochloric acid.

D

The primary osmoreceptors are located in the A) pons. B) kidney. C) stomach. D) hypothalamus. E) medulla.

D

The primary products of protein digestion are ________, ________, and ________. A) polysaccharides, disaccharides, monosaccharides B) triglycerides, fatty acids, glycerol C) nucleic acid polymers, DNA, RNA D) free amino acids, dipeptides, tripeptides

D

When the plasma concentration of a substance exceeds its renal concentration, more of the substance will be A) filtered. B) reabsorbed. C) secreted. D) excreted. E) None of the answers are correct.

D

Which of the following is most likely to be observed in a patient with compensated respiratory alkalosis? A) respiratory rate increases B) tidal volume increases C) kidneys conserve bicarbonate D) kidneys secrete fewer hydrogen ions E) body retains less carbon dioxide

D

difficulty breathing A. hyperpnea B. hyperventilation C. tachypnea D. dyspnea E. apnea

D

fluid accumulation in intersitital spaces A. fibrotic lung disease B. emphysema C. asthma D. pulmonary edema

D

increased diffusion distance A. fibrotic lung disease B. emphysema C. asthma D. pulmonary edema

D

Anabolism is a term that describes A) reactions that release energy. B) reactions that require a net input of energy. C) reactions that result in the synthesis of large biomolecules. D) reactions that release energy and reactions that result in the synthesis of large biomolecules. E) reactions that require a net input of energy and reactions that result in the synthesis of large biomolecules.

E

Angiotensin I is converted to angiotensin II by enzymes primarily located in the A) kidneys. B) liver. C) heart. D) lungs. E) blood vessels.

E

Saliva secretion is primarily a result of A) increased sympathetic stimulation. B) decreased parasympathetic stimulation. C) increased somatic motor stimulation. D) decreased somatic motor stimulation. E) increased parasympathetic stimulation.

E

Shrinkage of hepatocytes in the liver causes them to cause which of the following? A) glycogen production only B) glycogen breakdown only C) protein synthesis only D) both glycogen production and protein synthesis E) both glycogen breakdown and protein breakdown

E

The brain can use ________ for energy. A) only glucose B) only fats C) only ketones D) only lactate E) both glucose and ketones

E

The partial pressure of oxygen in arterial blood is approximately ________ mm Hg. A) 40 B) 45 C) 50 D) 70

E

The primary complex carbohydrate ingested and digested by people is A) fiber. B) glycogen. C) glucagon. D) cellulose. E) starch.

E

Which of the following concerning the hormone atrial natriuretic peptide is FALSE? A) produced by cells in the heart B) promotes sodium loss at the kidneys C) reduces blood pressure D) suppresses vasopressin secretion E) increases aldosterone secretion

E

Which of the following symptoms would you expect to observe in a person suffering from type I diabetes mellitus? A) glucosuria B) ketoacidosis C) thirst and polydipsia D) hyperglycemia E) All of these answers are correct.

E

cessation of breathing A. hyperpnea B. hyperventilation C. tachypnea D. dyspnea E. apnea

E

________ is characterized by a decreased surface area for gas exchange in the lungs

Emphysema

Name two functions of cholecystokinin

Enhances satiety, stimulates gallbladder contraction and pancreatic enzyme secretion, and inhibits gastric emptying and acid secretion. See Table 21.1 in the chapter

Proteins must first be enzymatically degraded to single amino acids before entering the capillaries of the hepatic portal system. Is this true or false? What is the significance of this? Is absorption of carbohydrates and lipids restricted to monomers? Explain.

False. Absorption of small peptides allows peptides to provoke food allergies. The transporters for peptides are also responsible for absorption of some drugs. Carbohydrates are digested to monosaccharides because there are no transporters for larger carbohydrates. Lipids are absorbed as cholesterol, fatty acids, and monoglycerides, primarily by simple diffusion because they are lipophilic.

Prior to the discovery of the role of insulin in metabolism and the development of insulin therapy to treat diabetes mellitus, a diagnosis of this disease was always fatal. What do untreated diabetics die from?

Figure 22.20 in the chapter provides a good summary of the effects of untreated diabetes mellitus. Metabolic acidosis and circulatory failure from dehydration are the primary triggers of death. Increased urination would lead to increased blood osmolarity and decreased blood volume/pressure. Decreased blood volume/pressure would be the stimulus to active the baroreceptors and the atrial stretch receptors (your text refers to them as volume receptors.) The baroreceptors would signal to the CVCC to increase SNS output. The SNS output would cause increased HR, SV, CO, and TPR that would all work together to help increase blood pressure. The baroreceptors would also signal to the posterior pituitary/hypothalamus to cause the release of anti-diuretic hormone. ADH would cause water reabsorption at the collecting duct, and this water reabsorption would help increase blood volume/pressure and decrease osmolarity. Both the baroreceptors and the atrial stretch receptors would signal to the thirst center in the brain to increase thirst, which would cause the patient to drink more water, increasing blood volume/pressure and decreasing osmolarity. Low blood volume/pressure would cause decreased GFR at the kidneys, which would mean lower fluid flow past the macula densa. As a result, the macula densa would signal to the granular cells to release renin. This renin release would be further reinforced, because the granular cells would also respond directly the decreased blood pressure and the increased SNS activity. Renin is necessary for the conversion of angiotensinogen to angiotensin II. Ang II does lots of things! Ang II would signal to the thirst center (causing increased thirst,) the posterior pituitary (causing increased ADH release,) the CVCC (causing increased SNS output,) directly to blood vessels all over the body (causing vasoconstriction, increased TPR, and increased blood pressure,) the proximal tubule (causing increased sodium/water reabsorption that would help increase blood volume/pressure,) and the adrenal cortex (attempting to cause aldosterone release.) However, the adrenal cortex would receive conflicting inputs: ang II telling it to release aldo, and high osmolarity telling it NOT to release aldo. Since the body protects osmolarity first, the adrenal cortex would not release aldo. Increased osmolarity activates the osmoreceptors, which would signal to the posterior pituitary to release ADH and the thirst center to increase thirst. Both these responses would again help increase blood volume/pressure and decrease osmolarity.

The amount of filtrate entering the proximal tubules of the kidneys each minute is the ________.

GFR

Explain why glucose or other simple sugars should NOT be the sole source of energy in our diets. What is the best approach to meeting energy needs?

Given that glucose only meets energy rather than other essential nutrient needs, a person consuming only glucose would die of malnutrition. A mixture of fats, proteins, simple sugars, and complex carbohydrates optimizes the storage, nutrient, and caloric needs of the various organ systems. Glucose requires a relatively large amount of water for hydration and a large amount of space for storage. Glycogen is more compact, and fat is the most compact and efficient means of energy storage.

"Glucose, glucose, everywhere, nor any speck to utilize" is a phrase made up by one of the authors working on this test question. Similar to the irony of not being able to prevent dehydration by drinking seawater, people with untreated diabetes mellitus are unable to prevent starvation despite the large amount of glucose surrounding their cells; as if that isn't bad enough, dehydration is also a problem. Explain why there is glucose in the urine of such people, why glucose is not present in the urine of normal people, and why diabetics become dehydrated.

Glucose is in the urine simply because the plasma concentration exceeds the number of glucose transporters in the kidney tubules, because plasma glucose is unusually high. Normal individuals are able to reabsorb all the glucose in the filtrate because plasma glucose concentrations are normally low (normal body cells absorb glucose, diabetic cells do not). Glucose in the filtrate raises the osmolarity of the filtrate, which decreases the relative osmotic gradient for reabsorption of water; thus more water is lost in the urine leading to dehydration.

Patrick's urine sample reveals a high concentration of glucose. Is glucose normally present in urine? Suggest two possible mechanisms to explain why the kidney would excrete excess glucose, and what abnormality may underlie those conditions

Glucose transporters may be saturated, preventing complete reabsorption of glucose (filtration exceeds reabsorption). This can happen with extremely high glucose ingestion or with untreated diabetes mellitus. A genetic defect resulting in an insufficient number of glucose transporters is another possibility.

Gossip, an undergraduate, has normal PCO2 levels, high H+ levels, low pH and bicarbonate levels. What type of disturbance is Gossip suffering from and what might cause this? If his PCO2 were elevated, would your answer change? Explain.

Gossip is likely suffering from metabolic acidosis, since his PCO2 is normal. If his PCO2 was elevated, then he would likely be suffering from respiratory acidosis. Metabolic acidosis may be caused by ingestion of methanol, aspirin, and ethylene glycol. Respiratory acidosis can be caused by drugs or alcohol depression, increased resistance in asthma, impaired gas exchange in fibrosis or severe pneumonia, and muscle weakness in muscular dystrophy and other muscle diseases. The most common cause is chronic obstructive pulmonary disease.

Do the factors affecting affinity of hemoglobin for oxygen have the same impact on loading and unloading in lungs and tissues? Explain your answer, and indicate if this presents a conflict in remedying hypoxia. Assuming a medical team has treatments available for changing all the factors affecting hemoglobin's oxygen affinity, how should they manipulate pH, temperature, PCO2, and 2,3-DPG content in a hypoxic patient?

Hemoglobin affinity changes in the same way in the lungs and tissues, thus increasing unloading in the tissues does decrease loading in the lungs, which seems as if one cancels out the other. But from the oxygen dissociation curves it is evident that the impact is greater in the tissues; thus increased unloading can remedy hypoxia. The medical team should decrease pH, increase temperature, increase PCO2, and increase 2,3-DPG.

A professor gave the following analogy of kidney function to his freshman biology class: "Imagine your desk is a disorganized mess, containing things worth keeping and things you should throw out. Instead of picking through each item one by one and considering if it is to keep or toss, you sweep your arm across your desktop in one smooth motion, knocking the entire contents of the desk into your large trash can. Then you pull the items you want to keep out of the trash can and place them back on your desk." In what ways is this analogy accurate? In what ways is it inaccurate? Some students in his class argue that the kidneys are inefficient and poorly designed. How should the professor respond? What modern medical device may he cite in his response?

His analogy is accurate in that the glomerulus does dump contents into the nephron that the body needs and will take back. His analogy is inaccurate in that the entire contents of the plasma are not dumped, rather about 1/5 of the volume enters the nephron. While one could easily imagine a more efficient way to remove waste from the blood, the kidneys can only use the tools they have, namely various membrane transport processes and the physical laws governing movement of water and solutes. Kidney dialysis machines rely on diffusion through semipermeable membranes, mimicking part of normal kidney function.

Define hyperventilation and explain what may cause it. Is the increased ventilation that occurs while exercising an example of hyperventilation? Explain your answer. How are PO2 and PCO2 affected by hyperventilation? Can breathing into a paper bag remedy hyperventilation or is this just unfounded folk medicine? Explain.

Hyperventilation is an increase in alveolar ventilation that exceeds metabolic demand. A person can deliberately hyperventilate, or it may occur as a result of emotional stress or high altitude. Strictly speaking, the increase in ventilation during exercise is necessary to meet increased metabolism and is therefore not hyperventilation. PO2 is increased and PCO2 is decreased during hyperventilation, because more O2 is inhaled and more CO2 is exhaled; this produces abnormally low PCO2. Hyperventilation can be remedied by a paper bag treatment, because rebreathing exhaled air will increase PCO2 in the body back to normal.

A condition known as lactose intolerance is characterized by painful abdominal cramping, gas, and diarrhea. The cause of the problem is an inability to digest the milk sugar, lactose. How would this cause the observed symptoms? Why is yogurt less likely to trigger the symptoms

If an individual cannot digest lactose, then the sugar will pass through to the large intestine in an undigested form. The presence of the extra sugar in the chyme increases the osmolarity of the chyme, resulting in less water being reabsorbed by the intestinal mucosa. The bacteria that inhabit the large intestine can metabolize the lactose, and in the process they produce large amounts of carbon dioxide. The gas overstretches the intestine, which stimulates local reflexes that increase peristalsis. The combination of more fluid contents and increased peristalsis produces the symptom of diarrhea. The overexpansion of the intestine by gas causes the severe pain and abdominal cramping, and of course, the increase in intestinal gas release is directly related to increased gas production by the bacteria. Yogurt contains bacteria that digest the lactose prior to the consumption of the yogurt.

High protein (low carbohydrate) diets have become popular in recent years. Based on what you've learned about metabolism and the body's energy needs, explain what might be some of the disadvantages of this type of diet.

Low carbohydrate diets shift the body to a fasting mode because glucose is needed for the brain, central nervous systems, and red blood cells. After glycogen stores have been depleted, the body will convert protein and fats into glucose and ketone bodies to provide the energy needed. The disadvantages of this shift are excess ketone bodies can seriously disrupt the body's pH balance (lead to ketosis) and loss of protein from body tissue (this occurs even when abundant protein from food is provided).

Diabetes mellitus produces many homeostatic imbalances, including acidosis. The pH imbalance is due to ketoacidosis, which results from excessive accumulation of by-products of fat metabolism, as the body cannot meet energy needs from carbohydrate metabolism. Maria is a teenaged diabetic who sometimes rebels by not taking her insulin. Her mother takes her to the hospital because her breathing has become deep and gasping. Explain Maria's breathing pattern. Which other compensatory responses may occur, and would they occur earlier or later than the respiratory response?

Maria's respiratory system is responding to her ketoacidosis. By hyperventilating, she removes more CO2 from her blood, which shifts the carbonic acid equation to the right, removing free H+ and raising pH. Chemical buffering in the blood occurs immediately after the initial pH disturbance, as this is an ongoing process. The kidneys buffer more slowly, so they are effective later.

Explain how oxygen and carbon dioxide are transported in the blood. How does the means of transport relate to the solubility and chemical reactivity of these gases in plasma?

Oxygen is not highly soluble in water, which is the main component of plasma. Less than 2% is dissolved in plasma, with the remainder bound to hemoglobin. The iron in the heme portion of the molecule can bind up to four oxygen atoms. Oxygen is not chemically reactive in the body. Carbon dioxide is more soluble than oxygen, at about 7% dissolved. Carbon dioxide is chemically reactive, combining with water to form carbonic acid, which then dissociates to bicarbonate and hydrogen ion. Most carbon dioxide is transported in the form of bicarbonate, about 70%, and the remaining 23% binds to amino acids on hemoglobin.

Which is typically more important in regulating the respiratory system, PO2 or PCO2?Explain your answer and briefly discuss the receptors involved. Give examples of situations in which each of those factors changes enough to stimulate a reflex. How and why are these factors related to each other?

PCO2 is the more important factor. For PCO2, there are central and peripheral receptors that respond to CO2 as well as to CO2-related pH. These receptors are very sensitive to routine changes in PCO2 and pH, such as those associated with an increase in physical activity. Peripheral chemoreceptors have been identified for O2, but these respond only to dramatic changes in PO2, such as those associated with high altitude or disease. Because CO2 is produced as a by-product of aerobic (oxygen-consuming) metabolism, an increase in CO2 is associated with a corresponding decrease in O2.

Draw a flow chart that shows the components of the reflex in which an increase in blood PCO2 leads to increased ventilation.

Peripheral chemoreceptors in carotid and aortic bodies detect changes in PCO2 and pH. Central chemoreceptors in the medulla oblongata monitor CO2 in CSF. Either an increase in PCO2 or decrease in pH will stimulate the receptors, which project to a control center in the medulla oblongata. The control center stimulates somatic motor neurons that control the skeletal muscles involved in ventilation. The effect is increased ventilation, which lowers PCO2 by eliminating CO2, so blood pH increases because of this shift. See Figure 18.17 in the chapter.

List, compare, and contrast the locations and stimuli for respiratory chemoreceptors.

Peripheral chemoreceptors in the carotid and aortic bodies sense changes in oxygen concentration, pH, and PCO2 of the plasma. Central chemoreceptors monitor cerebrospinal fluid composition and respond to changes in the concentration of CO2 in the cerebrospinal fluid

Sandy has insulin-dependent diabetes mellitus. Sandy has an accident on his bike and breaks his arm. Would his insulin dosage change?

Sandy will need increased levels of insulin. Insulin will promote the necessary healing by supporting anabolic reactions needed for regrowth of the bone. Students will learn in chapter 23 that prolonged stress (rather than the stress just at the time of the accident) will lead to increased blood glucose levels due to increased cortisol secretion, hence additional insulin will be needed to compensate for this as well.

Sharon "gets the wind knocked out of her" during a skiing accident in which she attempted a jump and landed hard on her feet before tumbling over. She is conscious but breathing is labored, and she complains of pain and shortness of breath. The first aid-trained ski patrolman that comes to her aid determines that Sharon has no broken bones, nor is CNS injury likely. He places tiny tubes at her nostrils that blow air (with higher than normal percentage of oxygen) into her nose then places her on the snowmobile, and takes her to the first aid tent. Why is Sharon's breathing labored? How does the high-oxygen air help her condition?

Sharon suffered an impact that increased her intrapleural pressure above normal, possibly by pushing her diaphragm upward, forcing her to expel some of her residual volume. With her alveoli smaller than normal, they are very difficult to inflate. The lack of broken ribs suggests that she does not have a pneumothorax. The air being blown into her nostrils has a higher PO2, which will increase the diffusion into her blood and compensate for her temporarily decreased tidal volume.

Cody has always carefully controlled her caloric intake, and is lean. During her unplanned pregnancy, she continued to eat the same, hoping that taking prenatal vitamins and minerals would ensure that her fetus would grow normally. Her only complication during pregnancy was persistent constipation and consequent hemorrhoids. She gained only the minimum weight suggested by her doctor, and delivered a healthy, full-term infant; her pre-pregnancy weight was rapidly reestablished. Propose an explanation for how she managed to gain enough weight, did not violate the law of conservation of mass, and for her only complication. What does this suggest about "eating for two" that some pregnant women do?

She must have inefficiently absorbed calories prior to her pregnancy, losing many potential calories in her feces. When she became pregnant, one of her physiological changes included an increase in nutrient (and thus calorie) absorption. This would also contribute to her constipation, as her feces retained less water than normal and thus were more difficult to eliminate. It is not possible for her to have gained more weight than she ate; no one can violate the law of conservation of mass. Most obstetricians recommend only a slight increase in calories during pregnancy for this reason, and women who indulge in overeating too often are likely to gain unnecessary body fat and may produce a fetus that is larger than it should be.

A chemistry student accidentally spills chlorine bleach into a dilute acid. The mixture reacts and produces fumes that are inhaled by the student and that reduce his ventilation. Assume that the gaseous chemical produced is a base (i.e., it releases OH- in an aqueous solution), and that the chemical is absorbed into the bloodstream at the alveoli. Explain why ventilation is reduced in the patient.

The physiological response is opposite that for acidosis. A decreased ventilation would reduce loss of CO2. By maintaining higher PCO2 in the blood, the resulting acidity would help to counteract the alkalinity resulting from the inhalation of a base.

Describe the pleura and explain its role in respiration.

The pleura is a double-walled sac that surrounds each lung. One wall clings to the lung surface, the other to the wall of the thoracic cavity. The pleura secretes and contains pleural fluid, which is a lubricant. Pleural fluid also keeps the wall of the lung in close proximity to the wall of the thoracic cavity, which is critical in the process of pulmonary ventilation.

The graph below shows an oxygen dissociation curve, with the normal curve in the center. What is the name of the phenomenon that shifts the curve to the right? What causes this change in oxygen dissociation? Is the shift beneficial or detrimental? Explain.

The shift in the dissociation curve is called the Bohr effect. The decrease in pH may be due to an increase in CO2 and lactic acid during vigorous physical activity, or to metabolic acidosis. The Bohr effect is beneficial, because the unloading of oxygen from hemoglobin increases under such conditions. If the decrease in pH is due to exercise, then the skeletal muscles have an increased demand for oxygen, and thus increased unloading is desirable.

Timmy is a cantankerous toddler who has just threatened that he will hold his breath until Mom gives him some chocolate. His mother refuses to be manipulated and watches in amusement as Timmy stubbornly refuses to breathe. To her horror, Timmy loses consciousness and collapses onto the floor. Her cousin, who is enrolled in a course for emergency medical technical (EMT) training, is visiting, and tells her there is no need to call for an ambulance. Why did Timmy lose consciousness? Should his mother trust her instincts and call for help and begin CPR, or should she listen to her well-meaning but young and inexperienced cousin? Explain.

Timmy loses consciousness due to hypoxia in his brain. There is no need for alarm, because the loss of consciousness indicates mainly that cerebral activity has decreased. The parts of the brain involved in respiratory control are in the brain stem. As long as Timmy was awake and determined, his cerebral signals were able to inhibit brain stem control of pulmonary ventilation. Once he loses consciousness, however, the respiratory control areas are released from inhibition and he starts breathing again. Soon normal oxygen content in the brain will be restored, and Timmy will wake up.

A newborn infant is found dead, abandoned by the road. Among the many questions that the police would like to have answers to is whether the infant was born dead or alive. After an autopsy, the medical examiner tells them that the infant was dead at birth. How could the medical examiner determine this?

Unless the infant was suffocated immediately at birth, the first breath that it took would start to inflate the lungs and some of the air would be trapped in the lungs. By placing the lungs in water to see if they float or not, the medical examiner can determine whether or not there is any air in the lungs. Other measurements and tests could also be used to determine if the infant had breathed at all (air in the lungs) or was dead at birth (lungs collapsed and a small amount of fluid in the alveoli).

The ________ are the long peritubular capillaries that dip into the medulla

vasa recta