Question

Filtration of plasma is dependent on the Hydrostatic pressure of blood. In situations of Hypotension, this is clearly compromised. To maintain (or raise) GFR, the kidney will:

Group of answer choices

A. Dilate Efferent Arteriole

B. Constrict Efferent and Afferent Arteriole

C. Dilate Afferent Arteriole

D. Constrict Afferent Arteriole

Answer 1

The kidneys regulate blood pressure by regulating renal blood flow. When there is decreased blood pressure (hypotension), the hydrostatic pressure decreases in the afferent arteriole. As a result, there is decreased stretch in the vascular smooth muscles lining the afferent arterioles. As a result, the inward direct ion channels will be inactivated, causing dilation of the smooth muscles. This will result in increased blood flow to the glomerulus. This will increase or maintain glomerular filtration rate as renal blood flow is increased.

The efferent arterioles are under the influence of RAAS system. The decrease in blood pressure activates the RAAS system, which then leads to production of angiotensin II and aldosterone. Angiotensin II will constrict the efferent arterioles. Hence, there is dilation of afferent arterioles and constriction of efferent arterioles.

Right choice: C. Dilate Afferent Arteriole