What effect does constricting the efferent arteriole have on the glomerular filtration rate?

• A. It causes the glomerular filtration rate to fluctuate.
• B. It decreases the glomerular filtration rate.
• C. It increases the glomerular filtration rate.
• D. It has no effect on the glomerular filtration rate.

Answer: (C)

Verified step by step guidance

1. Understand the role of the efferent arteriole in the nephron: The efferent arteriole carries blood away from the glomerulus after filtration has occurred.
2. Consider the effect of constriction on blood flow: Constricting the efferent arteriole increases resistance to blood flow, which can lead to changes in pressure within the glomerulus.
3. Apply the concept of hydrostatic pressure: Constriction of the efferent arteriole increases hydrostatic pressure in the glomerular capillaries, which is a key factor in determining the glomerular filtration rate (GFR).
4. Relate pressure changes to filtration rate: Increased hydrostatic pressure in the glomerulus enhances the filtration process, thereby increasing the glomerular filtration rate.
5. Conclude the effect: Constricting the efferent arteriole leads to an increase in the glomerular filtration rate due to elevated pressure within the glomerulus.