PRACTICE QUESTIONS
1. Which of the following statements accurately describes the pulmonary circulation?
a. It receives the total output of the right ventricle, except under conditions of alveolar hypoxia, when vasoconstriction reduces pulmonary blood flow.
b. The medial layer of the main pulmonary arteries is composed of a thick layer of smooth muscle.
c. The pulmonary veins return blood to the right atrium.
d. Unlike systemic capillaries, the pulmonary capillaries provide a large percentage of the total resistance to blood flow.
e. All the above
2. During exercise, cardiac output can increase fivefold, but pulmonary arterial pressure may not even double. This occurs because:
a. Pulmonary vascular resistance decreases during exercise.
b. Unperfused capillaries are recruited during exercise.
c. Previously perfused vessels are distended during exercise.
d. Factors that dilate the pulmonary arteries are released by the endothelium dUΓlΠg CXCΓCiSC.
e. All the above occur during exercise.
3. Which of the following will cause the greatest increase in pulmonary arterial pressure?
a. Exposure of a cow to the hypoxia of high altitude
b. A twofold increase in pulmonary blood flow
c. Stimulation of the vagus nerve (parasympathetic system) in a sheep
d. Inhalation of a tidal volume in a horse
e. None of the above will increase arterial pressure.
4. The bronchial circulation:
a. Receives the total output of the right ventricle.
b. Drains into the pulmonary circulation and azygos vein.
c. Vasoconstricts in response to hypoxia.
d. Supplies nutrient blood flow only to bronchi and no other structures.
e. Has a bronchial arterial pressure of the same magnitude as pulmonary arterial pressure.
5. In quadrupeds, pulmonary blood flow is distributed:
a. Within the lung, as would be predicted by the action of gravity.
b. Primarily to the ventral part of the lung during exercise.
c. So that the dorsal-caudal regions of the lung receive the most blood flow.
d. Uniformly among the alveoli.
e. Uniformly when the animal is anesthetized.