Final answer:
The autonomic nervous system regulates GFR by initiating vasodilation to increase GFR under resting conditions or inducing vasoconstriction through increased sympathetic nerve activity under stress, which reduces GFR. The tubuloglomerular feedback mechanism also plays a role in regulating GFR via paracrine signaling.
Step-by-step explanation:
Regulation of GFR by the Autonomic Nervous System
The autonomic nervous system regulates Glomerular Filtration Rate (GFR) through sympathetic nerve action. When sympathetic activity is reduced, vasodilation occurs resulting in increased blood flow and thus increased GFR.
During stress or when blood pressure falls, sympathetic activity increases causing vasoconstriction of afferent arterioles through norepinephrine and epinephrine release, and stimulates production of renin, which enhances the vasoconstrictor angiotensin II, reducing GFR.
Vasodilation of the afferent arterioles, however, increases blood flow and GFR, balancing the filtration rate. Additionally, tubuloglomerular feedback involves the Juxtaglomerular Apparatus (JGA) and macula densa cells, which respond to changes in fluid flow rate and Na+ concentration to regulate GFR through paracrine signals like ATP, adenosine, and nitric oxide (NO).