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Glomerular Filtration Rate (view source)
Revision as of 18:01, 9 December 2010
, 18:01, 9 December 2010no edit summary
====[[Renin Angiotensin Aldosterone System|Angiotensin 2]]====
====[[Renin Angiotensin Aldosterone System|Angiotensin 2]]====
====[[Sympathetic Nervous System effect on Glomerular Filtration Rate|Sympathetic Nervous System]]====
====Sympathetic Nervous System====
When the animal is in a situation of crisis or stress blood flow to the kidneys is reduced for the sake of other organs such as the brain, heart and skeletal muscles. The sympathetic nervous system and a heightened level of adrenalin in the plasma cause the contraction of both the afferant and efferant arterioles. As the efferant arteriole is contracted alongside the afferant one there is still a pressure differance allowing for filtration to still occur and reducing the impact on filtration compared to the impact on blood flow. At times when sympathetic tone is very high the renal blood flow could be reduced to 10-30% of normal. This practically stops filtration occuring and thus stops urine production.
'''Resting Sympathetic Activity'''
Unlike many other organs the kidneys have a low resting sympathetic tone. Therefore the sympathetic nervous system cannot effectively decrease the resistance by decreasing itself. This suggests that its main aim is to compensate for a fall in blood pressure or to prepare the body for the fight or flight response.
'''Effect on Reabsorption'''
As GFR is less affected than blood flow the filtration of what blood does pass through the glomerulus is more efficent. This means that the blood entering the pertitubular capillaries will have a higher protein osmotic pressure and a lower hydrostatic pressure as more of the plasma will have been filtered. This causes greater reabsorption of water and salt from the tubules. This causes urine volume to fall. It also stimulates [[Reabsorption and Secretion Along the Distal Tubule and Collecting Duct - Anatomy & Physiology#Juxtaglomerular Cells|renin]], [[Renin Angiotensin Aldosterone System|The Renin Angiotensin Aldosterone System (RAAS)]] and [[Aldosterone|aldosterone]] which all in turn have their effect on reabsorption.
'''Net Effect of Increased Sympathetic Nervous Activity on the Kidneys'''
* Reduced renal blood flow
* Small decrease in excreted waste
* Increased conservation of water and sodium
====[[The Effects of Nitrous Oxide and Prostaglandins on GFR - Anatomy & Physiology|Nitrous Oxide and Prostaglandins]]====
====[[The Effects of Nitrous Oxide and Prostaglandins on GFR - Anatomy & Physiology|Nitrous Oxide and Prostaglandins]]====
[[Category:Urinary System - Anatomy & Physiology]]
[[Category:Urinary System - Anatomy & Physiology]]