Hydrostatic Pressure

The hydrostatic pressure is much higher in the glomerulus than in ordinary capillaries. This high hydrostatic pressure enables about 20% of the plasma that flows through the glomerulus to be filtered into the Bowman's capsule. This filtrate is called the “filtration fraction”. As with all capillaries, the glomerulus retains erythrocytes and plasma proteins within the blood vessels, and filters an almost protein free “filtrate” into the Bowman's capsule. This filtrate contains water, electrolytes and low-molecular weight organic solutes.