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reabsorption
Reabsorption = (GFR X Px ) – (Ux X Px)
Total filtration = con. of sub. in plasma x GFR
Ux XPx = con. Of sub. in urine x urine flow rate
= urinary excretory rate
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Dr. Ashok Solanki
Factors affecting G.F.R.
Changes in renal blood flow
Changes in glomerular capillary hydrostatic pressure
Changes in systemic blood pressure
Afferent or efferent arteriolar constriction
Changes in hydrostatic pressure in Bowman's capsule
Ureteral obstruction
Edema of kidney inside tight renal capsule
Changes in concentration of plasma proteins: dehydration, hypoproteinemia, etc (minor factors)
Changes in Kf
Changes in glomerular capillary permeability
Changes in effective filtration surface area
Tubular function
Reabsorption Secretion Concentration Acidification of tubular fluid
Filtered load = Px X GFR Px = concentration of the substance in
plasma GFR = is the glomerular filtration rate
per unit of time
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Inulin clearance
Cin = Uin x V/ PinInulin is a polysaccharide, molecular
weight – 5200, it is not produce in our body, found in root of certain plants, administered I.V to a patient to measure GFR
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Inulin clearance Cin = Uin x V/ PinInulin is a polysaccharide, molecular
weight – 5200, it is not produce in our body, found in root of certain plants, administered I.V to a patient to measure GFR
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Renal clearance
Definition – renal clearance of a substance is the volume of plasma that is completely cleared of the substance by the kidney per unit time
Inulin clearance is equal to GFR - highly filtered - neither reabsorb nor secreted - non toxic - should not metabolized - easy to measure plasma concentration - urine concentration can be measured
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Dr. Ashok Solanki
Forces promoting & opposesing filtration
Net filtration force is +ve causing filtration
Dr. Ashok Solanki
Junction- the JGA
Blood flows into the glomerulus throughthe afferent arterioles and leaves theglomerulus through the efferentarterioles. The proximal tubule exits Bowman’s capsule.
Dr. Ashok Solanki 1804.02.2013
Dr. Ashok Solanki
Dr. Ashok Solanki
Dr. Ashok Solanki
Juxtaglomerular Apparatus
1. granular cells differentiated smooth muscle cells of
afferent arterioles secretory vesicles contain renin2. extraglomerular mesangial cells continuous with the mesangium3. macula densa cells terminal part of thick ascending limb
LOH probably control both renin secretion
and GFR
Dr. Ashok Solanki
Dr. Ashok Solanki