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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 ...
Angiotensin II causes the release of anti-diuretic hormone (ADH), [6] also called vasopressin – ADH is made in the hypothalamus and released from the posterior pituitary gland. As its name suggests, it also exhibits vaso-constrictive properties, but its main course of action is to stimulate reabsorption of water in the kidneys.
Juxtaglomerular cells secrete renin in response to a drop in pressure detected by stretch receptors in the vascular walls, or when stimulated by macula densa cells. Macula densa cells are located in the distal convoluted tubule, and stimulate juxtaglomerular cells to release renin when they detect a drop in chloride concentration in tubular fluid.
One cause of this can be increased renin production due to narrowing of the renal artery, or a juxtaglomerular cell tumor that produces renin. These will lead to secondary hyperaldosteronism, which will cause hypertension, high blood sodium, low blood potassium, and metabolic alkalosis. [citation needed]
The G i and increased intracellular calcium, cause a decrease in cAMP which inhibits Renin release from the juxtaglomerular cells. [14] In addition, when macula densa cells detect higher concentrations of Na and Cl, they inhibit nitric oxide synthetase (decreasing renin release), but the most important inhibitory mechanism of renin synthesis ...
Angiotensin is a peptide hormone that causes vasoconstriction and an increase in blood pressure. It is part of the renin–angiotensin system, which regulates blood pressure. Angiotensin also stimulates the release of aldosterone from the adrenal cortex to promote sodium retention by the kidneys. An oligopeptide, angiotensin is a hormone and a ...
It also results in the release of renin, which, through the renin–angiotensin system, causes constriction of the efferent arterioles, which ultimately increases hydrostatic pressure in the glomerulus. The process triggered by the macula densa helps keep the GFR fairly steady in response to varying artery pressure.
The kidneys secrete a variety of hormones, including erythropoietin, calcitriol, and renin. Erythropoietin is released in response to hypoxia (low levels of oxygen at tissue level) in the renal circulation. It stimulates erythropoiesis (production of red blood cells) in the bone marrow.