Liver Pancreas and Large Intestine Histology of the liver o Hepatocytes arranged in lobules o Sinusoids in between hepatocytes are blood filled spaces o Kupffer cells phagocytize microbes and foreign matter Pathway of bile secretion o Bile canaliculi o Hepatic ducts o Common hepatic ducts o Cystic duct from gallbladder and common hepatic duct join to form common bile duct o Common bile duct and pancreatic duct empty into duodenum Liver functions in carbohydrate metabolism o Gluconeogenesis turn amino acids into glucose o Gluconeogenesis turn triglycerides into glucose o Glycogenesis turn excess glucose into glycogen and store in the liver o Glycogenolysis turn glycogen back into glucose as needed Liver functions in lipid metabolism o Synthesize cholesterol o Synthesis lipoproteins such as HDL and LDL which are used to transport fatty acids and cholesterol into the bloodstream o Stores some fat o Breaks down some fatty acids Liver functions in protein metabolism o Deamination removes NH2 amine group from amino acids so can use what is left as energy source o Converts resulting toxic ammonia NH3 into urea for excretion by the kidney o Transamination converts one amino acid into another o Synthesizes plasma proteins utilized in the clotting mechanism and immune system Other liver functions estrogen Liver disease o Hepatitis o Detoxifies the blood by removing or altering drugs and hormones thyroid and o Removes bilirubin a waste product of red blood cell breakdown o Releases bile salts to help digestion by emulsification of lipids o Stores fat soluble vitamins including A D E K o Stores iron copper and vitamin B12 o Phagocytosis of worn out blood cells and bacteria o Activates vitamin D part of the vitamin activation pathway Inflammation of the liver that can be caused by a variety of viruses drugs or alcohol Can lead to cirrhosis o Cirrhosis Scarred liver caused by chronic inflammation due to hepatitis chemicals Composition and functions of pancreatic juice parasites or alcohol o 1 5 quarts day at pH of 7 1 to 8 2 o Contains water enzymes and sodium bicarbonate o Digestive enzymes Pancreatic amylase pancreatic lipase Proteases Trypsinogen activated by enterokinase a brush border ezyme Chymotrypsinogen activated by trypsin Procarboxypeptidase activated by trypsin Proelastase activated by trypsin Trypsin inhibitor combines with trypsin produced inside pancreas Ribonuclease and deoxyribonuclease digest nucleic acids Regulation of pancreatic secretions o Secretin acidity in intestine causes increased sodium bicarbonate release o CCK fats and proteins cause increased digestive enzyme released Function of the large intestine o Smooth muscle mechanical digestion o Peristaltic waves 3 to 12 contractions minute o Haustral churning relaxed pouches are filled from below by muscular contractions when full they contract and move contents to next pouch o Bacteria ferment undigested carbohydrates into carbon dioxide and methane gas and undigested proteins into simpler substances o Gastroilial reflex when stomach is full gastrin hormone relaxed ileocecal sphincter so small intestine will empty into large intestine o Gastrocolic reflex when stomach fills a strong peristaltic wave moves contents of transverse colon into rectum Defecation o Gastrocolic reflex moves feces into rectum o Stretch receptors signal sacral spinal cord o Parasympathetic nerves contract muscles of rectum and relax internal anal o External anal sphincter is voluntarily controlled sphincter Digestive health o Diarrhea Chyme passes too quickly through intestine H2O not absorbed o Constipation Decreased intestinal motility Too much water is absorbed Remedies are fiber exercise and water o Fiber Insoluble fiber Woody parts of plants wheat bran vegetable skins Speeds up transit time and reduces colon cancer Soluble fiber Gel like consistency beans oats citrus white parts apples Lowes blood cholesterol by preventing reabsorption of bile salts so liver has to use cholesterol to make more bile