Question

q: a condition causes a patients blood to become significantly thicker (higher viscosity) than normal. which of the following is the primary reason this increase in viscosity leads to high blood pressure?
description: sys2 blood v obj3c
a. the heart increases its contraction rate (heart rate) to speed up the sluggish blood flow.
b. the higher volume of thick blood puts extra strain on the vessel walls, causing them to constrict.
c. higher viscosity reduces the effective radius of the blood vessels, resulting in decreased flow.
d. increased viscosity increases systemic vascular resistance (svr), which raises blood pressure.

Explanation:

• Option A: The heart rate increase is not the primary reason for high blood pressure due to increased blood viscosity.
• Option B: Blood volume is not directly related to blood viscosity in this context.
• Option C: Viscosity does not reduce the effective radius of blood vessels.
• Option D: According to the formula \( BP = CO\times SVR\) (where \(BP\) is blood pressure, \(CO\) is cardiac output, and \(SVR\) is systemic vascular resistance), increased viscosity increases \(SVR\), which in turn raises blood pressure.

Answer:

D. Increased viscosity increases systemic vascular resistance (SVR), which raises blood pressure.