The glomerular filtration rate

The glomerular filtration rate - cells of the...

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The  glomerular filtration rate (GFR)  is the rate at which filtrate collectively accumulates in the  glomerulus of each nephron. The GFR, about 125 mL/min (180 liters/day), is regulated by the  following:  Renal autoregulation is the ability of the kidney to maintain a constant GFR even when the  body's blood pressure fluctuates. Autoregulation is accomplished by cells in the  juxtaglomerular apparatus that decrease or increase secretion of a vasoconstrictor substance  that dilates or constricts, respectively, the afferent arteriole. Neural regulation of GFR occurs when vasoconstrictor fibers of the sympathetic nervous  system constrict afferent arterioles. Such stimulation may occur during exercise, stress, or  other fight-or-flight conditions and results in a decrease in urine production. Hormonal control of GFR is accomplished by the renin/angiotensinogen mechanism. When 
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Unformatted text preview: cells of the juxtaglomerular apparatus detect a decrease in blood pressure in the afferent arteriole or a decrease in solute (Na + and Cl ) concentrations in the distal tubule, they secrete the enzyme renin. Renin converts angiotensinogen (a plasma protein produced by the liver) to angiotensin I. Angiotensin I in turn is converted to angiotensin II by the angiotensin-converting enzyme (ACE), an enzyme produced principally by capillary endothelium in the lungs. Angiotensin II circulates in the blood and increases GFR by doing the following: Constricting blood vessels throughout the body, causing the blood pressure to rise Stimulating the adrenal cortex to secrete aldosterone, a hormone that increases blood pressure by decreasing water output by the kidneys...
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