Sandbox Reserved 489: Difference between revisions
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The indirect mechanism, or the [http://en.wikipedia.org/wiki/Renin-angiotensin_system renin-angiotensin system] (RAS), controls blood volume and blood pressure through renin and two forms of [http://en.wikipedia.org/wiki/Angiotensin angiotensin]. Renin is involved in the first step of a cascade that eventually produces angiotensin II. The specialized granular cells of the [http://en.wikipedia.org/wiki/Juxtaglomerular_apparatus juxtaglomerular apparatus] secrete renin when stimulated by the [http://en.wikipedia.org/wiki/Macula_densa macula densa] when blood pressure or blood volume decreases. Renin circulating in the blood stream cleaves a small 10 residue portion of plasma protein angiotensinogen that is secreted by the liver. Cleavage of angiotensinogen produces the inactive precursor angiotensin I that is converted to angiotensin II by [http://en.wikipedia.org/wiki/Angiotensin-converting_enzyme angiotensin-converting enzyme] primarily in the lungs. Angiotensin II increases blood pressure in three ways. | The indirect mechanism, or the [http://en.wikipedia.org/wiki/Renin-angiotensin_system renin-angiotensin system] (RAS), controls blood volume and blood pressure through renin and two forms of [http://en.wikipedia.org/wiki/Angiotensin angiotensin]. Renin is involved in the first step of a cascade that eventually produces angiotensin II. The specialized granular cells of the [http://en.wikipedia.org/wiki/Juxtaglomerular_apparatus juxtaglomerular apparatus] secrete renin when stimulated by the [http://en.wikipedia.org/wiki/Macula_densa macula densa] when blood pressure or blood volume decreases. Renin circulating in the blood stream cleaves a small 10 residue portion of plasma protein angiotensinogen that is secreted by the liver. Cleavage of angiotensinogen produces the inactive precursor angiotensin I that is converted to angiotensin II by [http://en.wikipedia.org/wiki/Angiotensin-converting_enzyme angiotensin-converting enzyme] primarily in the lungs. Angiotensin II increases blood pressure in three ways. | ||
:*Angiotensin II constricts blood vessels by influencing smooth muscle tissue. The heart pumps faster to overcome the constricted arteries and blood pressure rises. | :*Angiotensin II constricts blood vessels by influencing smooth muscle tissue. The heart pumps faster to overcome the constricted arteries and blood pressure rises. | ||
*Angiotensin II stimulates | :*Angiotensin II stimulates the [http://en.wikipedia.org/wiki/Adrenal_cortex adrenal cortex] to secrete [http://en.wikipedia.org/wiki/Aldosterone aldosterone] that causes renal adsorption of sodium. when sodium moves into the blood stream water follows to increase the blood volume. | ||
