Question

Which of the following statements about the response of arteriolar smooth muscle to changing oxygen partial pressures is TRUE?

A. Both systemic and pulmonary arterioles respond to a decrease in PO₂ by constricting.
B. Both systemic and pulmonary arterioles respond to a decrease in PO₂ by dilating.
C. Systemic arterioles respond to a decrease in PO₂ by dilating, but pulmonary arterioles constrict in response to decreased PO₂.
D. Systemic arterioles respond to a decrease in PO₂ by constricting, but pulmonary arterioles dilate in response to decreased PO₂.
E. Changes in PO₂ do not affect arteriolar smooth muscle in the pulmonary system.

Answer 1

C. Systemic arterioles respond to a decrease in PO₂ by dilating, but pulmonary arterioles constrict in response to decreased PO₂.

Step-by-step explanation:

In the arterioles, vasoconstriction is a response to high oxygen while vasodilation is a response to carbon dioxide and low pH. However, in the pulmonary arterioles, vasoconstriction occurs as a response to low oxygen and this mechanism is called hypoxic pulmonary vasoconstriction (HPV).