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PART 4 Regulation and Maintenance

16. The oxygen-hemoglobin dissociation curve is adaptive because ita. shifts to the right in the pulmonary capillaries and to the left in thetissue capillaries.b. shifts to the left in the pulmonary capillaries and to the right in thetissue capillaries.c. does not shift.

17. Carbon dioxide is mostly transported in the blooda. dissolved in plasma.b. bound to blood proteins.c. within HCO 3− .d. bound to the heme portion of hemoglobin.e. bound to the globin portion of hemoglobin.

18. The chloride shifta. promotes the transport of CO 2 in the blood.b. occurs when Cl − replaces HCO 3− within red blood cells.c. maintains electrical neutrality in red blood cells and theplasma.d. All of these are correct.

19. Which of these parts of the brainstem is correctly matched with itsmain function?a. ventral respiratory groups—stimulate the diaphragmb. dorsal respiratory groups—limit inflation of the lungsc. pontine respiratory group—is involved in the switch betweeninspiration and expirationd. All of these are correct.

20. The chemosensitive areaa. stimulates the respiratory center when blood CO 2 levels increase.b. stimulates the respiratory center when blood pH increases.c. is located in the pons.d. stimulates the respiratory center when blood O 2 levels increase.e. All of these are correct.

21. Blood O 2 levelsa. are more important than CO 2 levels in the regulation of respiration.b. need to change only slightly to cause a change in respiration.c. are detected by sensory receptors in the carotid and aortic bodies.d. All of these are correct.

Answers in appendix E

1. A person’s vital capacity is measured while standing and while lyingdown. What difference, if any, in the measurement do you predict andwhy?

2. Ima Diver wanted to do some underwater exploration. Instead ofbuying expensive SCUBA equipment, she obtained a long hose andan innertube. She attached one end of the hose to the innertube so thatthe end was always out of the water, and she inserted the other end ofthe hose in her mouth and went diving. What happened to her alveolarventilation and why? How can she compensate for this change? Howdoes diving affect lung compliance and the work of ventilation?

3. The bacteria that cause gangrene ( Clostridium perfringens ) are anaero-bic microorganisms that do not thrive in the presence of O 2 . Hyperbaricoxygenation (HBO) treatment places a person in a chamber containingO 2 at three to four times normal atmospheric pressure. Explain howHBO helps treat gangrene.

4. One technique for artificial respiration is mouth-to-mouth resusci-tation. The rescuer takes a deep breath, blows air into the patient’smouth, and then lets air flow out. The process is repeated. Explain thefollowing: (1) Why do the patient’s lungs expand? (2) Why does airmove out of the patient’s lungs? (3) What effect do the P O 2 and theP CO 2 of the rescuer’s air have on the victim?

5. The left phrenic nerve supplies the left side of the diaphragm, and theright phrenic nerve supplies the right side. Damage to the left phrenicnerve results in paralysis of the left side of the diaphragm. Duringinspiration, does the left side of the diaphragm move superiorly, moveinferiorly, or stay in place?

6. Suppose that the thoracic wall is punctured at the end of a normalexpiration, producing a pneumothorax. Does the thoracic wall moveinward, move outward, or not move at all?

7. During normal, quiet respiration, when does the maximum rate ofdiffusion of O 2 in the pulmonary capillaries occur? When does themaximum rate of diffusion of CO 2 occur?

8. Experimental evidence suggests that the overuse of erythropoie-tin (EPO; see chapter 19) reduces athletic performance. What sideeffects of EPO abuse reduce exercise stamina?

9. Predict what would happen to tidal volume if (a) the vagus nerveswere cut, (b) the phrenic nerves were cut, or (c) the intercostal nerveswere cut.

10. You and your physiology instructor are trapped in an overturnedship. To escape, you must swim under water a long distance. Youtell your instructor it would be a good idea to hyperventilate beforemaking the escape attempt. Your instructor calmly replies, “Whatgood would that do, since your pulmonary capillaries are already100% saturated with oxygen?” What should you do and why?

11. Ima Anxious was hysterical and hyperventilating, so a doctor madeher breathe into a paper bag. An especially astute student said to thedoctor, “When Ima was hyperventilating, she was reducing bloodCO 2 levels; when she breathed into the paper bag, CO 2 was trappedin the bag, and she was rebreathing it, thus causing blood CO 2 levelsto increase. As Ima’s blood CO 2 levels increased, her urge to breatheshould have increased. Instead, she began to breathe more slowly.Please explain.” How do you think the doctor responded? ( Hint: Recall that the effect of decreased blood CO 2 on the vasomotor cen-ter results in vasodilation and a sudden decrease in bloodpressure.)

Answers in appendix F