GFR increases if:
Ans. B. Afferent arteriole dilates,Determinants of the GFR:a. GFR = Kf x Net filtration pressureb. Net filtration pressure =(PG-PB-pG+pB)i. PG = Glomerular hydrostatic pressure (= 60 mm Hg), promotes filtrationii. PB = Hydrostatic pressure in Bowman's capsule (= 18 mm Hg) which opposes filtrationiii. PG = Glomerular capillary colloid osmotic pressure (= 32 mm Hg), which opposes filtrationiv. PB = Bowman's capsule colloid osmotic pressure which promotes filtration, normally its value is zerov. ThereforeNet filtration pressure =(PG-PB-pG+pB)=60-18-32+0=+10mmHgc. Kf = Glomerular capillary filtration (ultrafiltration) co-efficient Kf is a measure of the product of the hydraulic conductivity (i.e. its permeability) and surface area of the glomerular capillaries. Its normal value for kidney is 12.5 ml/min/mm Hg of filtration pressure or 4.2 ml/min/mm Hg per 100 gm of kidney.Factors that increase or Decrease GFRa. Kf - "although increased Kfraises GFR, and decreased Kfreduces GFR, changes in Kfprobably do not provide a primary mechanism for the normal day to day regulation of GFR Kf - if decreases |GFRi. Measangial cells contraction |Kf |GFR; Angiotensin II important regulator of the mesangial cells contraction contraction |area available for filtration.ii. Thickness of the Glomerulary capillary BM i.e. |glom. capi. Permeability |Kf |GFR e.gchr. HTN, DM Agents causing contraction or Relaxation of mesangial cells i.e. | or |Kf i.e. -|or |GFR.
Afferent arteriole constricts
Afferent arteriole dilates
Efferent arteriole dilates
none of the above
Kidneys and Body Fluids