Anatomy And Physiology Ito!

ANATOMY AND PHYSIOLOGY HEPATOBILLARY TREE

ANATOMY OF THE 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). PHYSIOLOGY OF THE GALLBLADDER: 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.

Function of liver The liver has many functions. Some of the functions are: to produce substances that break down fats, convert glucose to glycogen, produce urea (the main substance of urine), make certain amino acids (the building blocks of proteins), filter harmful substances from the blood (such as alcohol), storage of vitamins and minerals (vitamins

A, D, K and B12) and maintain a proper level or glucose in the blood. The liver is also responsible fore producing cholesterol. It produces about 80% of the cholesterol in your body. Function of gall bladder The function of the gallbladder is to store bile and concentrate. Bile is a digestive liquid continually secreted by the liver. The bile emulsifies fats and neutralizes acids in partly digested food. A muscular valve in the common bile duct opens, and the bile flows from the gallbladder into the cystic duct, along the common bile duct, and into the duodenum (part of the small intestine). Function of duodenum The duodenum is largely responsible for the breakdown of food in the small intestine. Brunner's glands, which secrete mucus, are found in the duodenum. The duodenum wall is composed of a very thin layer of cells that form the muscularis mucosae. The duodenum is almost entirely retroperitoneal. The pH in the duodenum is approximately six. It also regulates the rate of emptying of the stomach via hormonal pathways. Function of pancreas The pancreas is a small organ located near the lower part of the stomach and the beginning of the small intestine. This organ has two main functions. It functions as an exocrine organ by producing digestive enzymes, and as an endocrine organ by producing hormones, with insulin being the most important hormone produced by the pancreas. The pancreas secretes its digestive enzymes, through a system of ducts into the digestive tract, while it secretes its variety of hormones directly into the bloodstream. Abnormal pancreatic function can lead to pancreatitis or diabetes mellitus. Function of cystic duct Bile can flow in both directions between the gallbladder and the common hepatic duct and the (common) bile duct. In this way, bile is stored in the gallbladder in between meal times and released after a fatty meal. Function of transverse colon

The large intestine comes after the small intestine in the digestive tract and measures approximately 1.5 meters in length. Although there are differences in the large intestine between different organisms, the large intestine is mainly responsible for storing waste, reclaiming water, maintaining the water balance, and absorbing some vitamins, such as vitamin K.

BILIRUBIN PRODUCTION AND ELIMINATION Bilirubin is the substance that gives bile its color. It is formed from senescent red blood cells. In the process of degradation, the hemoglobin from the red blood cell is broken down from biliverdin, which is rapidly converted to free bilirubin thru biliverdin reductase. Free bilirubin, which is not soluble in plasma, is transported in the blood attached to plasma albumin. Even when it is bound to albumin, this bilirubin is still called free bilirubin. As it passes through the liver, free bilirubin is released from its albumin carrier molecule and moved into the hepatocytes. Inside the hepatocytes, free bilirubin is converted to conjugated bilrubin thru glucoronyl transferase, making it soluble to bile. Conjugated bilirubin is secreted as a constituents of bile, and in this form, it passes through the bile ducts into the small intestine. In the intestine, approximately one half of the bilirubin is converted into a higly soluble substance called urobilinogen by the intestinal flora. Urobilinogen is either absorbed into the portal circulation or excreted in the feces. Most of the urobilinogen that is absorbed is returned to the liver to

be re-excreted into the bile. A small amount of urobilinogen, approximately 5% is absorbed into the general circulation and then excreted by the kidneys. Usually, only a small amount of bilirubin is found in the blood; the normal level of total serum bilirubin is 0.1 to 1.2 mg/dL. Laboratory measurements of bilirubin usually measure the free and the conjugated bilirubin as well as the total bilirubin. These are reported as the direct (conjugated) bilirubin and the indirect (unconjugated or free) bilirubin.

ANATOMY OF THE PANCREAS: Pancreas, conglomerate gland lying transversely across the posterior wall of the abdomen. It varies in length from 15 to 20 cm (6 to 8 in) and has a breadth of about 3.8 cm (about 1.5 in) and a thickness of from 1.3 to 2.5 cm (0.5 to 1 in). Its usual weight is about 85 gm (about 3 oz), and its head lies in the concavity of the duodenum. ANATOMY OF THE PANCREAS: The pancreas has both an exocrine and an endocrine secretion. The exocrine secretion is made up of a number of enzymes that are discharged into the intestine to aid in digestion. The endocrine secretion, insulin, is important in the metabolism of sugar in the body. Insulin is produced in small groups of especially modified glandular cells in the pancreas; these cell groups are known as the islets of Langerhans. The failure of these cells to secrete sufficient amounts of insulin causes diabetes