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RS 7
Hormonal Regulation, RS 8
Nervous Regulation - Coggle Diagram
RS 7
Hormonal Regulation
- Hormones that cause vasoconstriction, and thereby decrease RBF and GFR include:
- causes profound vasoconstriction of the afferent and efferent arterioles.
- It is secreted by endothelial cells of renal vessels, mesangial cells and distal tubular cells.
- Its production is elevated in a number of glomerular diseases.
- in low concentrations, causes a predominant constriction of the efferent arterioles.
- However, at higher concentrations, it causes
constriction of both afferent as well as efferent arterioles.
- causes an intense vasoconstriction of both afferent and efferent arterioles.
- Hormones that cause vasodilatation, and thereby increase RBF and GFR include:
- Prostaglandins (PGE2 and PGI2)
- is a vasodilator that acts by stimulating the release of NO and prostaglandins.
- Atrial natriuretic peptide (ANP).
- Its secretion by the heart rises with
hypertension and expansion of extracellular fluid volume.
- It causes vasodilatation of the afferent arterioles and vasoconstriction of efferent arterioles.
- The net effect of ANP is therefore to produce a
modest increase in GFR with little change in RBF.
- when administered in therapeutic doses, increase RBF and GFR.
- The proximal tubule produces the vasodilator hormone dopamine which increases RBF and inhibits renin secretion.
- increases RBF without elevating GFR, by decreasing the resistance of afferent and efferent arterioles.
- causes vasodilatation of both afferent and efferent arterioles.
- In addition, it also decreases total peripheral resistance.
- are produced locally within the kidneys in conditions such as haemorrhage and increase
RBF by
dampening the vasoconstrictor effects of sympathetic nerves and angiotensin II.
RS 8
Nervous Regulation
The afferent and efferent arterioles are innervated by sympathetic nerve
fibres from T10 to L2
intermediolateral grey segments of spinal cord
through the splanchnic nerves. The sympathetic cell bodies are located
in the superior mesenteric ganglion.
Under normal circulatory conditions, sympathetic tone is minimum.
Mild to moderate stimulation of sympathetic nerves usually has mild
effects on RBF because of autoregulation mechanism.
Strong acute stimulation of sympathetic nerves may produce marked fall
in RBF temporarily due to constriction of both afferent and efferent
arterioles. This effect is mediated mainly by α1
-adrenergic receptors and
to a lesser extent by postsynaptic α2
-adrenergic receptors.