Question

Which of the following usually decreases glomerular filtration rate? Choose all that are correct

A. a decrease in arterial pressure

B. a decrease in plasma protein level

C. a decrease in sympathetic nervous system output

D. a decrease in atrial natriuretic hormone

Answer 1

Option A & C

**Decrease in arterial pressure-

When mean arterial blood pressures is between 80 and 180 mm Hg, autoregulation mechanism maintains renal blood flow, so GFR remains constant.When mean arterial blood pressure drops below 80 mm Hg---There is decreased renal blood flow--Decreased GFR

**Sympathetic nervous system Output-

Sympathetic Stimulation can cause vasoconstriction ,Rennin angiotensin mechanism & release of Aldosterone which all causes Increase in GFR

Reduction of sympathetic stimulation results in vasodilation and decrease in GFR

** decrease in plasma protein level cause decrease in osmotic pressure, increase in GFR

Net Filtration Pressure=Glomerular hydrostatic pressure-[Colloid osmotic pressure of glomerular blood + Capsular Hydrostatic Pressure]

**Colloid osmotic pressure of glomerular blood-- This is pressure induced by proteins(Mostly albumin).

This pressure draws water into the glomerulus.

As Colloid Osmotic Pressure Increases Net filtration pressure Decreases.

a **decrease in atrial natriuretic hormone Increase GFR

ANP released by Atria cause Vasodialation which reduce GFR,So when ANP reduces GFR increase