q9 - guest1

[ArchivalUser]

A 43-year-old woman is found to have a blood pressure of 200/140 during a routine examination for a life
insurance policy. Further examination reveals retinal hemorrhages and the electrocardiogram (ECG) shows left
axis deviation. Which of the following is most likely to be decreased in this woman?


A. Arteriolar density

B. Arteriolar wall thickness

C. Arteriolar wall-to-lumen ratio

D. Capillary wall-to-lumen ratio

E. Total peripheral resistance

[ArchivalUser]

c.

[ArchivalUser]

A.?

[ArchivalUser]

A.agree...

[ArchivalUser]

Explanation:

The correct answer is A. This woman has malignant hypertension. The hypertension has caused left ventricular
hypertrophy and it is likely that hypertrophy of arteries and arterioles has occurred as well. Another
consequence of long-term hypertension is arteriolar rarefaction, i.e., dissolution and loss of arterioles. Although
the mechanism of arteriolar rarefaction is poorly understood, it is believed to result from long-term
over-perfusion of the tissues. Organs and tissues in which the vasculature has primarily a nutritive function
(e.g., brain, heart, skeletal muscle) regulate their blood flow in accordance with the metabolic needs of the
tissues. These tissues exhibit short-term autoregulation of blood flow such that the increase in blood flow
caused by elevated arterial pressure is minimized by arteriolar constriction. When the increased blood pressure
persists for weeks to months, many of the constricted arterioles close off and are resorbed. Therefore, the
arteriolar rarefaction that occurs in hypertensive individuals is an example of long-term autoregulation.