kidney

Definition

noun
  • either of two organs situated in the lower part of the back on either side of the spine behind the abdomen, whose function is to maintain the usual concentrations of the main constituents of blood, passing the waste matter into the urine.
COMMENT A kidney is formed of an outer cortex and an inner medulla. The nephrons which run from the cortex into the medulla filter the blood and form urine. The urine is passed through the ureters into the bladder. Sudden sharp pain in back of the abdomen, going downwards, is an indication of a kidney stone passing into the ureter.
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