APPLIED RADIOLOGICAL ANATOMY

Detailed explanation-1: -The forces that govern filtration in the glomerular capillaries are the same as any capillary bed. Capillary hydrostatic pressure (Pc) and Bowman’s space oncotic pressure (i) favor filtration into the tubule, and Bowman’s space hydrostatic pressure (Pi) and capillary-oncotic pressure (c) oppose filtration.

Detailed explanation-2: -Increases in the glomerular capillary hydrostatic pressure cause increases in net filtration pressure and GFR. However, increases in Bowman space hydrostatic pressure causes decreases in filtration pressure and GFR.

Detailed explanation-3: -In blood vessels supplying the renal corpuscles, the average hydrostatic pressure is about 1 kPa. The average hydrostatic pressure falls to a value of 0.04 kPa within the postcardinal vein efferent to the renal corpuscle. Within the glomerular capillaries the hydrostatic pressure averages 0.21 kPa.

Detailed explanation-4: -The glomerular capillary hydrostatic pressure is affected by the afferent and efferent arteriolar resistance and the renal artery pressure (3). An increase in the afferent arteriolar diameter (decrease in resistance) causes an increase in the glomerular capillary hydrostatic pressure and an increase in GFR.