Answer:
Angiotensin II is a potein VASOCONSTRICTOR that helps regulate blood pressure. Angiotensinogen, is an inactive hormone synthesized and released continuously from the LIVER. Its activation, which occurs within the BLOOD, is initiated by the enzyme renin. Renin is released from the juxtaglomerular apparatus of the KIDNEYS in response to either (1) LOW blood pressure (as detected by decreased stretch of BARORECEPTORS within granular cells, or by decreased NaCl detected by CHEMORECEPTORS within macula densa cells); or (2) stimulation by the SYMPATHETIC division. The sequential action of renin and angiotensin converting enzyme (ACE) causes the formation of angiotensin II (the active form of the hormone).
Explanation:
Angiotensin is a peptide hormones that regulate blood pressure by causing increase in blood pressure through vasoconstriction. It is a part of the renin- angiotensin system that regulate the internal pressure of the blood. It is stimulated when the level of blood pressure reduces or there is an decrease in the sodium chloride in the blood. It effects is to vasoconstrict the blood vessels thereby increasing the blood pressure in the vessels. Angiotensinogen is the inactive hormone synthesized by the liver and upon activation through baroreceptors or chemoreceptors, the liver releases angiotensinogen into the blood stream to be ctivated by the enzyme secreted from the kidney's juxtaglumerular apparatusand then activated to teh angiotensinogen I, angiotensinoI is then activated into angiotensin II by the angiotensin II by the angiotensin converting enzyme. Angiotensin also causes the increase in the aldosterone secretion from the adrenal cortex to promote the retention of sodium by the kidneys, this also helps to increaee the blood pressure. Various receptors helps in signalling the body to a reduced blood pressure level. This includes the baroreceptors which are pressure receptors and detect changes in pressure of the blood; chemorecptors which are chemical receptors that detect the change in the concentration of sodium and chloride ion in the blood. All this function together with the sympathetic division of the CNS to help the body regulates its change in blood pressure in a given time.
