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Renin (etymology and pronunciation), also known as an angiotensinogenase, is an aspartic protease protein and enzyme secreted by the kidneys that participates in the body's renin-angiotensin-aldosterone system (RAAS)—also known as the renin-angiotensin-aldosterone axis—that increases the volume of extracellular fluid (blood plasma, lymph, and interstitial fluid) and causes arterial ...
Renin is produced by juxtaglomerular cells, also known as granular cells. These cells are similar to epithelium and are located in the tunica media of the afferent arterioles as they enter the glomeruli. [4] The juxtaglomerular cells secrete renin in response to: Stimulation of the beta-1 adrenergic receptor
Changes in renin ultimately alter the output of this system, principally the hormones angiotensin II and aldosterone. Each hormone acts via multiple mechanisms, but both increase the kidney's absorption of sodium chloride, thereby expanding the extracellular fluid compartment and raising blood pressure. When renin levels are elevated, the ...
Juxtaglomerular cells (JG cells), also known as juxtaglomerular granular cells are cells in the kidney that synthesize, store, and secrete the enzyme renin. [1] They are specialized smooth muscle cells mainly in the walls of the afferent arterioles (and some in the efferent arterioles) [citation needed] that deliver blood to the glomerulus.
[9] [11] [12] Outside the kidneys, renin is predominantly picked up from the circulation but may be secreted locally in some tissues; its precursor prorenin is highly expressed in tissues and more than half of circulating prorenin is of extrarenal origin, but its physiological role besides serving as precursor to renin is still unclear. [13]
The kidneys produce renin [32] and erythropoietin [33] hormones, and are involved in the conversion of vitamin D to its active form. [34] Mammals are the only class of vertebrates in which only the kidneys are responsible for maintaining the homeostasis of the extracellular fluid in the body. [35]
When renal blood flow is reduced (indicating hypotension) or there is a decrease in sodium or chloride ion concentration, the macula densa of the distal tubule releases prostaglandins (mainly PGI2 and PGE2) and nitric oxide, which cause the juxtaglomerular cells lining the afferent arterioles to release renin, activating the renin–angiotensin–aldosterone system, to increase blood pressure ...
They resemble smooth muscle cells and play a role in renal autoregulation of blood flow to the kidney and regulation of systemic blood pressure through the renin–angiotensin system. Extraglomerular mesangial cells are part of the juxtaglomerular apparatus , along with the macula densa cells of the distal convoluted tubule and the ...