Regulation of Renal Blood Flow and GFR

Jan 10, 2024223

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Under normal physiological conditions, the body regulates blood flow to specific areas through self-regulation. The kidneys play a crucial role in regulating blood flow and maintaining stability within a blood pressure range of 80-160mmHg. When blood pressure is high, the body employs mechanisms such as vasodilation and contraction of smooth muscles to adjust blood flow. Additionally, the nervous and hormonal systems also contribute to regulating blood vessel constriction and dilation. During periods of rest, the body relies on self-regulation to maintain stable blood flow and normal urinary function. However, in situations like severe bleeding, the body activates neurohumoral mechanisms to constrict renal blood vessels and redistribute blood flow to vital organs such as the brain and heart.

Under normal physiological conditions, self-regulation occurs, and special circumstances will only be neurologically regulated (blood is redistributed to areas that need it more).

Self-regulation#

Renal blood flow depends on blood pressure/resistance.
The renal arterial pressure can regulate blood flow and stabilize GFR between 80-160mmHg. Outside this range, blood flow increases when blood pressure is elevated.

Myogenic mechanism: When blood pressure increases, blood vessels dilate, pulling on the endothelial calcium channels, causing calcium influx and smooth muscle contraction.
[[Tubuloglomerular feedback]]

Neurohumoral regulation#

Vasoconstriction during excitement
Sympathetic nervous system stimulation causes vasoconstriction and decreased blood flow;
Epinephrine, norepinephrine, AngⅡ, vasopressin
Vasodilation during relaxation
Prostaglandins, acetylcholine, atrial natriuretic peptide

During periods of rest within the normal range of blood pressure fluctuations, self-regulation is primarily relied upon to maintain relatively stable blood flow and normal urinary function.
In cases of significant bleeding and other situations, neurohumoral regulation causes renal vasoconstriction, redistribution of systemic blood flow, and allocation of blood to vital organs such as the brain and heart.