All of the following statements about Renal Regulation in a patient with Hypovolemic shock are true, except:
Correct Answer: Constriction of Afferent aerioles more than the Efferent aeriole
Description: Systemic hypoperfusion leads to increased release of the Vasoconstrictor Angiotensin II. Angiotensin II mediates greater constriction of the efferent aeriole than the afferent aeriole promoting a propoionately greater fall in renal plasma flow in glomerular filtration rate.This is a physiologically appropriate adaptation since it preferentially shunts blood to the critical coronary and cerebral circulation, while maintaining GFR and therefore excretory capacity. Renal Regulation in Disorders with Systemic Hypoperfusion Systemic hypoperfusion leads to increased release of vasoconstrictors, Angiotensin II and Norepinephrine . Angiotensin II increases resistance at the efferent aeriole more than at the afferent aeriole Norepinephrine affects both afferent and effferent aerioles to a smiliar degree The net effect is renal vasoconstriction (not vasodilationn as with pure autoregulation), a potentially marked reduction in renal plasma flow, and a slight fall or even no change in GFR due to the effect of efferent constriction This is a physiologically appropriate adapatation since it preferentially shunts of blood to the critical coronary and cerebral circulation , while maintaining GFR and therefore excretory capacity. Ref: Renal Pathophysiology: The essential 4th edition Pgno: 22
Category:
Physiology
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