Which of the following equations best depicts the factors determining mean arterial blood pres-sure?

a. Mean arterial pressure = cardiac output ÷ vascular resistance
b. Mean arterial pressure = cardiac output ? vascular resistance
c. Mean arterial pressure = right atrial pres-sure ? aortic pressure
d. Mean arterial pressure = vascular re-sistance ÷ cardiac output

ANS: B
Average blood pressure in the circulation is directly related to both cardiac output and flow re-sistance.
Mean arterial pressure = cardiac output ? vascular resistance.