bladder, urinary

bladder, urinary,

muscular sac located in the pelvis that stores urineurine,
clear, amber-colored fluid formed by the kidneys that carries metabolic wastes out of the body (see urinary system). As the blood circulates it collects excretory products from the tissues and these substances are separated from the blood by the kidneys and eliminated
..... Click the link for more information.  and contracts to expel it from the body. Urine enters the bladder from the kidneys through the uretersureter
, thick-walled tube that conveys urine from the kidney to the urinary bladder. It is approximately 10 in. (25.4 cm) long, with the upper half located in the abdomen and the lower half in the pelvic region.
..... Click the link for more information.  and is discharged from the body via the urethraurethra
, canal in most mammals that carries urine from the bladder to the outside of the body; in the male it also serves as a genital duct. The urethra is about 1 1-2 in. long (3.8 cm) in women, terminating above the vaginal opening. In men the urethra is about 8 in.
..... Click the link for more information. . The bladder of the adult human can hold over a pint (0.6 liters) of urine. When the level of urine reaches about half this amount, pressure of the accumulating fluid stimulates nervous impulses that relax the external sphincter, a muscle that forms a dense band around the urethra at the base of the bladder. This muscle can be controlled voluntarily in most mammals. The muscles in the wall of the bladder also contract, forcing urine out through the urethra. The bladder is subject to infection (commonly called cystitiscystitis
, common acute or chronic inflammation of the urinary bladder. The disease occurs primarily in young women and frequently results from bacterial invasion of the urethra from the adjacent rectum, most commonly with normally occurring intestinal bacteria such as E.
..... Click the link for more information. ) and the formation of stones. Its normal function may also be affected by nervous disorders or by external pressure, as from prostatic enlargement or pregnancy. See urinary systemurinary system,
group of organs of the body concerned with excretion of urine, that is, water and the waste products of metabolism. In humans, the kidneys are two small organs situated near the vertebral column at the small of the back, the left lying somewhat higher than the
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