DrG 23: 7 of 8

All of the following provide chemoreceptor input to the respiratory centers of the medulla oblongata, except the A) olfactory epithelium. B) medullary chemoreceptors. C) aortic body. D) carotid body. E) All of the answers are correct.

A

Sympathetic input to the smooth muscle tissue in bronchioles causes all of these except A) bronchoconstriction. B) a bigger lumen. C) less airway resistance. D) activation of beta-two receptors. E) relaxation.

A

The percent of oxygen saturation of hemoglobin when the pH is 7.6 is A) greater than the percent of oxygen saturation of hemoglobin when the pH is 7.2. B) less than the percent of oxygen saturation of hemoglobin when the pH is 7.2. C) equal to the percent of oxygen saturation of hemoglobin when the pH is 7.2.

A

The percent of oxygen saturation of hemoglobin when the temperature is 38 degrees centigrade is A) greater than the percent of oxygen saturation of hemoglobin when the temperature is 43 degrees centigrade. B) less than the percent of oxygen saturation of hemoglobin when the temperature is 43 degrees centigrade. C) equal to the percent of oxygen saturation of hemoglobin when the temperature is 43 degrees centigrade.

A

Which of the following factors would increase the amount of oxygen discharged by hemoglobin to peripheral tissues? A) decreased temperature B) decreased pH C) increased tissue PO2 D) decreased amounts of DPG E) All of the answers are correct.

B

In quiet breathing, A) inspiration and expiration involve muscular contractions. B) inspiration is passive and expiration involves muscular contractions. C) inspiration involves muscular contractions and expiration is passive. D) inspiration and expiration are both passive. E) inspiration is deep and forceful.

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

Under quiet conditions, blood returning to the heart retains about ________ of its oxygen content when it leaves the lungs. A) 25 percent B) 50 percent C) 75 percent D) 90 percent E) 100 percent

C

The term hypercapnia refers to A) the cessation of breathing. B) elevated PCO2. C) elevated PO2. D) an increase in pH. E) labored breathing.

B

A 10-percent 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) decrease the vital capacity.

B

Each 100 ml of blood leaving the alveolar capillaries carries away roughly ________ ml of oxygen. A) 10 B) 20 C) 30 D) 50 E) 75

B

Hemoglobin's affinity for oxygen when the BPG level is high is A) greater than hemoglobin's affinity for oxygen when the BPG level is low. B) less than hemoglobin's affinity for oxygen when the BPG level is low. C) equal to hemoglobin's affinity for oxygen when the BPG level is low.

B

Low pH alters hemoglobin structure so that oxygen binds less strongly to hemoglobin at low PO2. This increases the effectiveness of A) external respiration. B) internal respiration. C) carbon dioxide transport. D) hemoglobin synthesis. E) acid-base balance.

B

Most of the oxygen transported by the blood is A) dissolved in plasma. B) bound to hemoglobin. C) in ionic form as solute in the plasma. D) bound to the same protein as carbon dioxide. E) carried by white blood cells.

B

The apneustic centers of the pons A) inhibit the pneumotaxic and inspiratory centers. B) provide stimulation to the inspiratory center. C) monitor blood gas levels. D) alter chemoreceptor sensitivity. E) generate the gasp reflex.

B

The most important chemical regulator of respiration is A) oxygen. B) carbon dioxide. C) bicarbonate ion. D) sodium ion. E) hemoglobin.

B

At a PO2 of 70 mm Hg and normal temperature and pH, hemoglobin is ________ percent saturated with oxygen. A) 10 B) 25 C) 50 D) 75 E) more than 90

E

Carbonic anhydrase A) is in RBCs. B) is an enzyme. C) can increase the amount of bicarbonate ion in plasma. D) can decrease the amount of bicarbonate ion in plasma. E) All of the answers are correct.

E

For maximum loading of hemoglobin with oxygen at the lungs, the A) PCO2 should be high. B) pH should be slightly acidic. C) PO2 should be about 70 mm Hg. D) DPG levels in the red blood cells should be high. E) PCO2 should be low.

E

Which statement about the chloride shift is false? A) involves a movement of chloride ion into RBCs B) depends on the chloride-bicarbonate countertransporter C) involves a movement of bicarbonate ions into the plasma D) is driven by a rise in PCO2 E) causes RBCs to swell

E