How the Body Works: The Filtering Mechanism

The filtering mechanism occurs at the Bowman's capsule of each nephron. As blood flows through the glomerular tuft, small molecules are forced through pores in the capillary walls into the nephron. Red blood cells and large protein molecules remain. The filtrate flows down the tubule and is joined by organic wastes and excess salts secreted from surrounding kidney tissues. Most of the glucose, amino acids, vitamins and essential salts are reabsorbed into the blood, leaving a concentrated solution, urine.