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kidney kid·ney (kĭd'nē)
n. pl. kid·neys
Either of a pair of organs in the dorsal region of the vertebrate abdominal cavity, functioning to maintain proper water and electrolyte balance, regulate acid-base concentration, and filter the blood of metabolic wastes, which are then excreted as urine.
Either of a pair of organs that are located in the rear of the abdominal cavity in vertebrates. The kidneys regulate fluid balance in the body and filter out wastes from the blood in the form of urine. The functional unit of the kidney is the nephron. Wastes filtered from the blood by the nephrons drain into the ureters, muscular tubes that connect each kidney to the bladder. See also nephron.
A pair of organs, the principal parts of the excretory system, located above the waistline at the back of the abdominal cavity. The kidneys filter waste materials from the blood, excreting these wastes in the form of urine; they also regulate the amounts of water and other chemicals in body fluids.