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The net pressure gradient that causes the fluid to filter out of the glomeruli into the capsule is -
A
20 mm Hg
B
50 mm Hg
C
75 mm Hg
D
30 mm Hg
Detailed Solution
Filtration in the glomerulus depends on the balance of three pressures.
Glomerular hydrostatic (blood) pressure, which pushes fluid out of the capillaries into the Bowman's capsule: about 75 mm Hg.
Colloidal osmotic pressure of the plasma proteins, which opposes filtration: about 30 mm Hg.
Hydrostatic pressure of the filtrate in the Bowman's capsule (capsular pressure), which also opposes filtration: about 25 mm Hg.
Net filtration pressure $= 75 - (30 + 25)$
$= 20$ mm Hg
So the net pressure gradient that causes filtration is 20 mm Hg.
Glomerular hydrostatic (blood) pressure, which pushes fluid out of the capillaries into the Bowman's capsule: about 75 mm Hg.
Colloidal osmotic pressure of the plasma proteins, which opposes filtration: about 30 mm Hg.
Hydrostatic pressure of the filtrate in the Bowman's capsule (capsular pressure), which also opposes filtration: about 25 mm Hg.
Net filtration pressure $= 75 - (30 + 25)$
$= 20$ mm Hg
So the net pressure gradient that causes filtration is 20 mm Hg.