If the Diameter of an Artery Decreases, the Pressure Inside

Question

If the diameter of an artery decreases, the pressure inside will:
A) increase.
B) be unaffected.
C) decrease.
D) fluctuate at random.

Accepted Answer

According to the principle of fluid dynamics, specifically Bernoulli's principle, if the diameter of a tube (in this case, an artery) decreases, the velocity of the fluid (blood) flowing through it increases. According to the equation of continuity and Bernoulli's equation, this results in a decrease in pressure. However, in the physiological context of blood flow, the situation is more accurately described by Poiseuille's law, which indicates that resistance increases as the diameter decreases, leading to an increase in pressure upstream of the constriction to maintain flow. This is why the correct answer is that pressure inside the artery increases.