Anatomy and Physiology

ANATOMY AND PHYSIOLOGY GALLBLADER Located in right hypochondriac region. It is a pear-shaped sac from 7-10cm long and 3cm brbroadoad at its widest point. Can hold 30-50 ml of bile. Divided into four anatomic portions: the fundus, the corpus or body, infundibulum, and the neck. GALLBLADDER The gallbladder (or cholecyst, sometimes gall bladder) is a small organ whose function in the bodbodyy is to harbor bile and aid in the digestive process. Anatomy The cystic duct connects the gall bladder to the common hepatic duct to form the common bile duct. The common bile romero duct then joins the pancreatic duct, and enters through the hepato pancreatic ampulla at the major duodenal ppapilla.apilla. The fundus ooff the gallbladder is the part ffarthestarthest from the duct, located by the lower border ooff the liver . It is at the same level as the transptranspyloricyloric plane. Microscopic anatomy The different layers of the gallbladder are as follfollows:ows: The gallbladder has asimple columnar epithelial lining chcharacterizedaracterized by Recesses called Aschoff's recesses, which are pouches inside the lining. Under the epithelium there is a layer of connective tissue(lamina propria) Beneath the connective tissue is a wall of smooth mmuscle(muscularisuscle(muscularis externa) that contractscontracts in responsresponsee to cholecystokinin, a peptide hormone secreted by theduodenum. There is essentially n osubmucosa separating the connnectivenective tissue from serosa and adventitia. Size and Location of the Gallbladder The gallbladder is a hollow, pear-shaped sac from 7 to 10 cm (3-4 inches) long and 3 cm broad at its widest point. It consists of a fundus, body and necneck.k. It can hold 30 to 50 ml of bile. It lies on the undersurface of the liver’s right lobe and is attached there by areolar connective tissue. Structure of the Gallbladder Serous, muscular, and mucous layers compose the walwalll of the gallbladder. The mucomucosalsal lining is arranged in folds called rugae, similar in structure to those of the stomach FUNCTIONS OF THE GALLBLADER: The gallbladder stores bile that enters it by wawayy ooff the hepatic and cystic ducts. During this time the gallbladder concentrates bile fivefold to tenfold. Then later, when digestion occurs in the stomach and intestines, the gallbladder contracts, ejecting the concentrated bile into the duodenum. Jaundice a yellow discoloration of the skin and mucosa, results when obstruction of bile flow into the duodenum occurs. Bile is thereby denied its normal exit from the bodbodyy in the feces. Instead, it is absorbed into the blood, and an excess of bile pigments with a yellow hue enters the blood and is deposited in the tissues. The gallbladder stores about 50 mL (1.7 US fluid ouncesounces// 1.8 Imperial fluid ounces) of bile, wwhichhich is released when food containing fat ententersers the digestdigestiveive tract, stimulating the secretion of cholecystokcholecystokinininin (CCK). The bile, produced in the liver, emulsifies fats and neutralizes acids in partlypartly digested food. After being stored in the gallbladder the bile becomes more concentrated than when it left the liver , increasing its potency and intensifying its effect on fats. Most digestion occurs in the duodenum. LIVER A.A. Location and size of the liver- largest gland in the body, weighs aapproximatelypproximately 11.5.5 kg; lies under the diaphragm; occupies most of the right hypochondrium and part of the epigastrium. B.B. Liver lobes and lobules- two lobes separatseparateded by the falciformfalciform ligament 1.Left lobe- forms about one sixth of the liver 2.Right lobe- forms about five sixths of the liver; divides into right lobe pproper,roper, caudate lobe, and quadrate lobe3.Hepatic lobules- anatomical units of the liver; small branch of hepatic vein extenextendsds through the center of each lobule C.C. Bile ducts Small bile ducts form right and left hepatic duductscts Right and left hepatic ducts immediately join to form one hepatic duct Hepatic duct merges with cystic duct to form the common bile duct, which opens into the duodenum D.D. Functions of the liver 1. Glucose Metabolism -- after a mmeal,eal, glucose is taken up from the portal venous blobloodod by the liver and converted into glycogen ( glycogenesis), which is stored in the hepatocytes.hepatocytes. GlycoGlycogenisgenis converted back to glucose (glycogenolysis) and release as needed into the blood stream to maintain normal level of the blood glucose.-glucose can be synthesized by the liver through the process gluconeogenesis 2. Ammonia Conversion- use of amino acids from protein for gluconeogenesis rresultesult in the formation of ammonia as a by product. Liver converts ammonia to urea 3. Protein Metabolism- Liver synthesizes almost all of the plasma protein including albumin, alpha and beta globulins, blood clotting factors plasma lipoproteins 4. Fat Metabolism- Fatty acid can be broken down for the production of energy and production of ketone bodies 5.Vitamin and Iron Storage -stores vitamin A, D, E, K 6. Drug Metabolism 7. Bile Formation - bile is formed by the hepatochepatocytes-composedytes-composed of wawater,ter, electrolytes such as sodium,sodium, potassium, calcium, chloride, bicarbonate, lecithin, fatty acids, cholesterol, bile salts-collected and stored in the gallbladder and emptied in the intestine when needeneededd for digestion a. Lecithin and bile salts emulsify fats by encasing them in shells to form tiny spheres called micellmicelleses b. Sodium bicarbonate increases pH for optimum enzyme function c. Cholesterol, products of detoxification, and bile pigments (e.g. bilirubin) are wastes products excexcreretedted by the liver and eventually eliminated in the feces.

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