Blood entering the glomerulus is under high hydrostatic pressure because the diameter of the afferent arteriole is larger than the diameter of the efferent arteriole

High hydrostatic pressure causes ultrafiltration to occur, that is, fluid seeps through the walls of the glomerulus capillaries into the cavity of Bowman’s capsule

The fluid that enters Bowman’s capsule is known as the glomerular filtrate

The glomerular filtrate has the same composition as blood plasma but does not contain red blood cells, platelets and plasma proteins

Red blood cells and plasma proteins remain in the blood flowing to the efferent arteriole because the size of these substances is too large to seep out of the glomerulus

Reabsorption of the glomerular filtrate occurs along the renal tubule

The dissolved substances permeate across the renal tubular walls into the blood capillary network

In the proximal convoluted tubule, sodium ions (Na+) are actively pumped into the blood capillary network and chloride ions (Cl–) are passively absorbed

The reabsorption of 100% glucose and amino acids also occurs through active transport.