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Gallbladder.

Publié le 06/12/2021

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Gallbladder.
Gallbladder, muscular organ that serves as a reservoir for bile, present in most vertebrates. In humans, it is a pear-shaped membranous sac on the undersurface of the
right lobe of the liver just below the lower ribs. It is generally about 7.5 cm (about 3 in) long and 2.5 cm (1 in) in diameter at its thickest part; it has a capacity varying
from 1 to 1.5 fluid ounces. The body (corpus) and neck (collum) of the gallbladder extend backward, upward, and to the left. The wide end (fundus) points downward
and forward, sometimes extending slightly beyond the edge of the liver. Structurally, the gallbladder consists of an outer peritoneal coat (tunica serosa); a middle coat
of fibrous tissue and unstriped muscle (tunica muscularis); and an inner mucous membrane coat (tunica mucosa).
The function of the gallbladder is to store bile, secreted by the liver and transmitted from that organ via the cystic and hepatic ducts, until it is needed in the digestive
process. The gallbladder, when functioning normally, releases bile through the biliary ducts into the duodenum to aid digestion by promoting peristalsis and absorption,
preventing putrefaction, and emulsifying fat. See Digestive System.
The major disorder associated with the gallbladder is the presence of gallstones, varying in shape and size from a pea to a small pear. Accreted from the constituent
salts in the bile, they are most common in diabetic patients, in blacks, and in women; their presence increases with age. Two of the reasons for the growth of gallstones
are believed to be the presence of excessive amounts of substances such as calcium and cholesterol in the bile and the retention of bile in the gallbladder for a long
period of time. The usual treatment for gallstones is surgical removal. Two naturally occurring bile salts, chenodeoxycholic acid and ursodeoxycholic acid, taken orally
dissolve gallstones in some patients. Ultrasound (see Ultrasonics) treatment to shatter the stones also eliminates the need for surgery in some cases.
Another common disorder of the gallbladder is cholecystitis, or inflammation of the organ, which is believed to be a result of the presence of highly concentrated bile.
Chronic cholecystitis is sometimes aggravated by bacterial infection, leading to perforation and peritonitis. Less common is the growth of malignant tumors, which are
associated with gallstones and constitute about 3 percent of all cancer in humans.

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