NEET PG Medical – 2019 – Question – 22
Tubuloglomerular feedback control is useful for which one of the following?
a) GFR
b) Plasma sodium
c) Plasma volume
d) Determining tubular secretion
Correct Answer – A
Ans: A. GFR.
Tubuloglomerular feedback – Two components:
* Afferent arteriole feedback mechanism- Usually referred as “Tubuloglomerular feedback”
* Efferent arteriole feedback mechanism.
Afferent arteriolar feedback mechanism:
* Transmitter involved – Adenosine causing Ca2+ channel opening.
Efferent arteriolar feedback mechanism:
* Activates renin-angiotensin system generating angiotensin II→ efferent arteriole constriction → ?ed GFR.
* Feedback depends on juxtaglomerular apparatus & its specialized cells.
– Macula densa – Specialized epithelium of distal tubule in close contact with afferent arteriole
