Filtration occurs in the glomerulus, while the majority of reabsorption occurs in the proximal convoluted tubule of the nephron. The kidneys filter approximately 200 quarts of blood per day, according to the National Kidney and Urologic Diseases Information Clearinghouse.
The kidneys are responsible for filtering wastes out of the blood and maintaining normal fluid and electrolyte balances. Each kidney has approximately one million filtering units called nephrons, which filter harmful wastes out of the blood. In people with kidney disease, the kidneys do not filter the blood as well as they should. As a result, minerals and waste products build up in the bloodstream, causing fatigue, nausea and other symptoms.