Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

biophysics In the kidneys the hydrostatic pressure in the glomerular capillaries

ID: 38742 • Letter: B

Question

biophysics

In the kidneys the hydrostatic pressure in the glomerular capillaries (GC) is greater than most capillaries in order to facilitate filtering of the blood to the bowman's space (BS) through reverse osmosis. The hydrostatic pressure of the blood entering the GC is 60mmHg=8000Pa, while the hydrostatic pressure is slightly negative in the BS at -15mmHg=-2000Pa. Water and small molecules like glucose and urea can pass freely through the capillary walls, but these walls are impermeable to plasma proteins. If there is no protein in Bowman's space, what will be the concentration of protein in the blood as it exits the Glomerular capillaries? (for no assume that hydrostatic pressure is constant throughout this process)

Explanation / Answer

The glomerulus filters small molecular weight substances like glucose, urea, amino acids salts and water etc.. These are passed through filtration membrane into the bowman'sca[sule and retained. Proteins and molecules associated with proteins are not filtered by the filtration membrane and glomerules and hence they are returned to plasma. If there is no protein in the Bowman's space, the concentration of blood will be more that exits from glomerular capillaries. This is because high molecular weight substances like proteins are returned to blood plasma and hence, concentration of blood increases.