flow and filtration Flashcards
renal blood flow: recall what proportion of cardiac output normally perfuses the kidney, explain the effect of changes in renal blood flow on glomerular filtration rate (GFR) and be able to calculate renal plasma flow rate given appropriate values
basic renal process (blood vessels and tubular fluid)
blood from renal artery → afferent arteriole → [glomerular filtration → tubule for reabsorption and secretion → final urine for excretion] → efferent arteriole → peritubular capillary [reabsorption and secretion] → renal vein [and ureter]
what is the driving force of glomerular filtration
hydrostatic pressure in glomerular capillaries due to blood pressure
opposing pressure to driving hydrostatic pressure in glomerular capillaries
hydrostatic pressure of tubule, osmotic pressure of plasma proteins in glomerular capillaries (as proteins not present in tubule)
what does net ultrafiltration pressure equal
hydrostatic pressure in glomerular capillaries - hydrostatic pressure of tubule - oncotic pressure of glomerular capillaries
what is the normal net ultrafiltration pressure
120 mmHg
what is the glomerular filtration rate equal to
net ultrafiltration pressure x ultrafiltration coefficient
what determines ultrafiltration coefficient
membrane permeability and SA available for filtration
what is renal blood flow approximately equal to
1L/min (1/5 of cardiac output)
what is renal plasma flow approximately equal to
0.6L/min
