Question

Tubuloglomerular feedback control is useful for which one of the following?

• A. GFR
• B. Plasma sodium
• C. Plasma volume
• D. Determining tubular secretion

Answer 1

The Correct Option is A

Tubuloglomerular feedback is a critical regulatory mechanism in renal physiology. It primarily serves to maintain or adjust the Glomerular Filtration Rate (GFR) within optimal limits. This mechanism involves the detection of sodium chloride concentration by the macula densa cells located in the distal convoluted tubule. When there is an increase in GFR, more sodium reaches the distal tubule, which is sensed by the macula densa. In response, these cells release signals that cause vasoconstriction of the afferent arteriole, thereby reducing blood flow into the glomerulus and bringing down the GFR.

Therefore, the primary function of tubuloglomerular feedback is the regulation of GFR.

Option	Functionality
GFR	Regulation of Glomerular Filtration Rate
Plasma sodium	Not directly regulated by tubuloglomerular feedback
Plasma volume	Indirectly influenced but not a direct control target
Determining tubular secretion	Not the primary control mechanism