NBME Physiology 2

Question 1

A patient has a cardiac output of 6 L/min and a heart rate of 75 bpm. What is the stroke volume?

Accepted Answer

80 mL

Answer

Stroke volume = cardiac output ÷ heart rate = 6000 mL/min ÷ 75 bpm = 80 mL.

Question 2

During isovolumetric contraction, which valves are open?

Accepted Answer

Neither aortic nor mitral valves

Answer

During isovolumetric contraction, all four cardiac valves are closed as ventricular pressure rises before the aortic valve opens.

Question 3

Which condition causes a leftward shift of the oxygen-hemoglobin dissociation curve?

Accepted Answer

Alkalosis

Answer

Alkalosis raises pH, decreasing H+ concentration and increasing hemoglobin's oxygen affinity, shifting the curve leftward.

Question 4

Hypoxic pulmonary vasoconstriction primarily serves to:

Accepted Answer

Redirect blood to better-ventilated lung segments

Answer

Hypoxic pulmonary vasoconstriction diverts blood from poorly oxygenated alveoli to better-ventilated regions, optimizing V/Q matching.

Question 5

In the West lung zones, which pressure relationship defines Zone 1?

Accepted Answer

Alveolar > arterial > venous

Answer

Zone 1 (lung apex) has alveolar pressure exceeding arterial pressure, collapsing capillaries and creating dead space with no gas exchange.

NBME Practice Test