MCAT Question A Day - 3/17/14 - Answer!

Blood pressure is a function of cardiac output (heart rate 3 stroke volume), as well as peripheral resistance (a measure of friction between the blood and the blood vessel walls). Factors that can

increase peripheral resistance include

A. vasoconstriction and low blood viscosity.

B. vasoconstriction and high blood viscosity.

C. vasodilation and low blood viscosity.

D. vasodilation and high blood viscosity.

The correct answer is (B). A general understanding of blood pressure concepts, and the factors that influence blood pressure, is required. If peripheral resistance reflects friction between the blood and the walls of the blood vessels, both narrower blood vessels (vasoconstriction) and a thicker, more viscous blood will increase peripheral resistance.

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