Kidneys
The kidneys, a pair of bean-shaped organs at the back of the abdominal cavity, one on each side of the spinal column, are one of the body's primary execretory mechanisms.
They filter the blood and remove toxins that have been made water-soluable by complex enzymatic processes (see How the body detoxes. ) that take place in the liver. The kidneys also remove ammonia that results during the break-down of the amino acids used in many bodily processes.
Another job the kidneys perform is in helping to balance the body's internal environment by removing excess water, gases, salts and other organic materials, while conserving the substances the body requires for its normal functioning. The kidneys do this by a process of selective filtering. The qualitative aspects of this job are better appreciated when the volume of filtering is understood.
Each day, about 1,700 quarts of blood flows through the kidneys. Of that volume, only about 180 quarts is filtered, and of this fluid, 178 quarts is reabsorbed; the remaining amount, only one to two quarts, passes off as urine. In all, the kidneys filter an amount equal to the entire volume of blood about 30 to 36 times per day.
The ureter carries urine from the kidneys to the bladder where it is stored until it is voluntarily expelled at intervals.
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