liver Flashcards
the livers size and location
is the largest gland in the body. Located under the diaphragm, more to the right side of the body, it overlies and almost completely covers the stomach (look back at Figure 14.5a). The liver has four lobes and is suspended from the diaphragm and abdominal wall by a delicate mesentery cord, the falciform (fal′sĭ-form) ligament.
the livers digetive function
The liver has many critical metabolic and regulatory roles; however, its digestive function is to produce bile. Bile leaves the liver through the common hepatic duct and enters the duodenum through the bile duct (look back at Figure 14.6).
Bile
Bile is a yellow-to-green, watery solution containing bile salts, bile pigments (chiefly bilirubin, a breakdown product of hemoglobin), cholesterol, phospholipids, and a variety of electrolytes. Of these components, only the bile salts (derived from cholesterol) and phospholipids help the digestive process. Bile does not contain enzymes, but its bile salts emulsify fats by physically breaking large fat globules into smaller ones, thus providing more surface area for the fat-digesting enzymes to work on.
The gallbladder
is a small, thin-walled green sac that snuggles in a shallow fossa in the inferior surface of the liver (look back at Figure 14.6). When food digestion is not occurring, bile backs up the cystic duct and enters the gallbladder to be stored. While in the gallbladder, bile is concentrated by the removal of water. Later, when fatty food enters the duodenum, a hormonal stimulus prompts the gallbladder to contract and spurt out stored bile, making it available to the duodenum.
diseases of the gallbladder or liver
If bile is stored in the gallbladder for too long or too much water is removed, the cholesterol it contains may crystallize, forming gallstones. Gallstones can become stuck in one of the ducts leading from the gallbladder to the duodenum, causing agonizing pain when the gallbladder contracts (an event called a gallbladder attack).
Blockage of the common hepatic or bile ducts (for example, by wedged gallstones) prevents bile from entering the small intestine, and it begins to accumulate and eventually backs up into the liver. This exerts pressure on the liver cells, and bile salts and bile pigments begin to enter the bloodstream. As the bile pigments circulate through the body, the tissues become yellow, or jaundiced. Blockage of the ducts is just one cause of jaundice. More often it results from actual liver problems such as hepatitis, an inflammation of the liver, or cirrhosis (sir-ro′sis), a chronic inflammatory condition in which the liver is severely damaged and becomes hard and fibrous. Hepatitis is most often due to viral infection resulting from drinking contaminated water or transmitted in blood via transfusion or contaminated needles. Cirrhosis is almost guaranteed when someone drinks alcoholic beverages in excess for many years, and it is a common consequence of severe hepatitis.
