Renin-Angiotensin System

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The Renin-Angiotensin system (RAS), also Renin-Angiotensin-Aldosterone system, is one of the mechanisms used by the body to regulate [[blood pressure|blood pressure]]. It comes into play when the [[blood pressure|blood pressure]] is too low, in disease it can happen when the [[blood pressure|blood pressure]] is not low which can lead to [[hypertension|hypertension]].   
 
The Renin-Angiotensin system (RAS), also Renin-Angiotensin-Aldosterone system, is one of the mechanisms used by the body to regulate [[blood pressure|blood pressure]]. It comes into play when the [[blood pressure|blood pressure]] is too low, in disease it can happen when the [[blood pressure|blood pressure]] is not low which can lead to [[hypertension|hypertension]].   
  
=== <u>Mechanism</u>  ===
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== <u></u>Mechanism<u></u>  ==
  
Low [[blood pressure|blood pressure]] is detected by the juxtaglomerular apparatus&nbsp;which&nbsp;secretes&nbsp;renin. This&nbsp;[[Enzyme|enzyme]] hydrolyses&nbsp;angiotensinogen&nbsp;in the blood stream to [[angiotensin I|angiotensin I]]. Angiotensin&nbsp;I is further processed; [[angiotensin-converting-enzyme|angiotensin-converting-enzyme]] (ACE), released from the lungs, cleaves further [[Amino acids|amino acids]]&nbsp;from the protein resulting in [[angiotensin II|angiotensin II]]. This [[protein|protein]] help the body to raise the [[blood pressure|blood pressure]] by many mechanisms including [[vasoconstriction|vasoconstriction]], [[ADH|ADH]] secretion and [[aldosterone|aldosterone]] secretion.
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Low [[Blood pressure|blood pressure]] is detected by the juxtaglomerular apparatus&nbsp;which&nbsp;secretes&nbsp;renin. This&nbsp;[[Enzyme|enzyme]] hydrolyses the precursor protein&nbsp;angiotensinogen&nbsp;in the blood stream to [[Angiotensin I|angiotensin I]]. Angiotensin&nbsp;I is further processed by&nbsp;[[Angiotensin-converting-enzyme|angiotensin-converting-enzyme]] (ACE) which is&nbsp;released from the lungs, and&nbsp;cleaves further [[Amino acids|amino acids]]&nbsp;from the protein resulting in [[Angiotensin II|angiotensin II]]. This [[Protein|protein]] helps the body to raise the [[Blood pressure|blood pressure]] by many mechanisms including [[Vasoconstriction|vasoconstriction]], [[ADH|ADH]] secretion and [[Aldosterone|aldosterone]] secretion. [[Aldosterone|Aldosterone]] acts on the collecting duct and the distal tubule of the [[Kidney|kidneys]] and increases the activity of [[ENaC channels|ENaC channels]]. This will then allow for an increase in [[Sodium|sodium]] uptake which will&nbsp;pass into the blood, with water following via [[osmosis|osmosis]], helping to raise [[Blood_pressure|blood pressure]].

Latest revision as of 11:38, 1 November 2011

The Renin-Angiotensin system (RAS), also Renin-Angiotensin-Aldosterone system, is one of the mechanisms used by the body to regulate blood pressure. It comes into play when the blood pressure is too low, in disease it can happen when the blood pressure is not low which can lead to hypertension

Mechanism

Low blood pressure is detected by the juxtaglomerular apparatus which secretes renin. This enzyme hydrolyses the precursor protein angiotensinogen in the blood stream to angiotensin I. Angiotensin I is further processed by angiotensin-converting-enzyme (ACE) which is released from the lungs, and cleaves further amino acids from the protein resulting in angiotensin II. This protein helps the body to raise the blood pressure by many mechanisms including vasoconstriction, ADH secretion and aldosterone secretion. Aldosterone acts on the collecting duct and the distal tubule of the kidneys and increases the activity of ENaC channels. This will then allow for an increase in sodium uptake which will pass into the blood, with water following via osmosis, helping to raise blood pressure.

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