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Renin-Angiotensin-Aldosterone System

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Submitted By Cgrand
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How the RAAS system works? The renin-angiotensin-aldosterone system (RAAS) this system helps keep the body’s sodium and water in balance. The system also helps maintain a close to normal blood volume and blood pressure. “The enzyme renin will be secreted when afferent arteriole’s sense a drop in blood pressure, in response to sympathetic stimulation, and when the macula densa senses decreased numbers of chloride, potassium, and sodium ions” (Shier, Butler, & Lewis, 2012 pg.476). The juxtaglomerular cells will secrete renin (enzyme) in response to the stimuli.
Once the renin is secreted and in the bloodstream it acts with the plasma protein angiotensinogen to form angiotensin I. Angiotensin I will act to a second enzyme angiotensin-converting enzyme ACE (in lungs and plasma) will quickly convert to angiotensin II and angiotensin II will stimulate aldosterone from the adrenal glands (Shier, et. al 2012). Why will the body activate the RAAS system? For example when there is a drop in blood pressure in the body the RAAS system will sense the change and secrete renin once activated by the stimuli (drop in blood pressure). Renin binds or acts on angiotensinogen to form angiotensin I and converts to angiotensin II. Angiotensin II will cause vasoconstriction on the efferent arterioles, thus in simple terms will help raise blood pressure. Another aspect is that angiotensin II will act on the kidneys and stimulate the adrenal gland to secret the hormone aldosterone. Aldosterone can reabsorb sodium and water, which can help raise blood pressure. (Shier, et. al, 2012) The three classes of drugs that will affect this system and why and when they are used? Angiotensin-converting enzyme inhibitors (ACE inhibitors) this drug prevents the conversion of angiotensin I to angiotensin II and this decreases peripheral arterial resistance (arteriole dilation) decreasing

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