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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 ...
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.
Locally expressed renin–angiotensin systems have been found in a number of tissues, including the kidneys, adrenal glands, the heart, vasculature and nervous system, and have a variety of functions, including local cardiovascular regulation, in association or independently of the systemic renin–angiotensin system, as well as non ...
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]
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 kidneys also carry out functions independent of the nephrons. For example, they convert a precursor of vitamin D to its active form, calcitriol; and synthesize the hormones erythropoietin and renin. Chronic kidney disease (CKD) has been recognized as a leading public health problem
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 dipsogen . It is derived from the precursor molecule angiotensinogen, a serum globulin produced in the liver .
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 ...