Metab Study Guide FINAL GI tract o Anything in the GI isn t in the body until its in the bloodstream o It is the waiting room for food o Consist of Mouth Esophagus Liver accessory Gallbladder accessory Pancreas accessory Large I small I Rectum Stomach o Accessory organs help with digestion of food o Mastication chewing Breaks down food o Saliva contains enzymes Its made at the base of the tongue Salivary amylase carbohydrates Salivary lipase milk fat Kill bacteria First defense against bacteria in food o And lysosomes o Esophagus stomach Muscular tube that connects the back of the mouth and the Moves food through peristalsis Has the lower esophageal sphincter circular muscular valve When it relaxes lets food into the stomach Also constricts to keep food from moving back up into esophagus GERD heartburn Relaxation of lower esophageal sphincter When the esophagus doesn t have protective lining to Stomach acid comes in contact with esophagus protect against stomach acid Can lead to ulcers and increased risk of cancer Holds the food and you have mechanical and breaking down of o Stomach food Gastric secretions Gastrin o Release of HCL and pepsinogen Pepsinogen denatures proteins o Activated by HCL HCL denatures protein and also denatures lingual lipase which stops the digestion of fats and carbs in stomach o Also kills bacteria Absorption of alcohol and aspirin The mucus protects stomach lining and contains bicarbonate which neutralizes acid Intrinsic factor is necessary for absorption of B12 If we don t have this it can lead to macrositic anemia Circular muscular valve separating stomach from duodenum Regulates movement of food and acid from stomach to small I When it doesn t work you have dumping of food into small I and it doesn t allow for proper absorption o Pyloric sphincter o CHYME ACID FOOD o Small intestine 3 sections duodenum o MAIN site of digestion and absorption o Receives secretions from other digestive organs through the common bile duct This is where secretions from the liver pancreas and gall bladder enter SM I o Lining of the small intestine is folded into finger like projections called villi o Villi are line with enterocutes that contain microvilli o Look like a brush so its called the brush border and this is where the digestion of nutrients usually are completed o Enterocytes fuly functional cells that line the villi produce enzymes have a nucleus etc Villar tip cells slough off get more of the nutrients or enzyme mid villar cells make digestive hormone CCK secretin GIP crypt cells proliferation of new entero cells o digestion and absorption continues o absorption and enterohepatic circulation of bile jejunum ileum large intestine has a smooth lining with no vili has a lot of bacteria for breakdown of fiber intestinal microflora o most immune cells in the gut o also produce some B and K vitamins this is where we have absoption of water and electrolytes Temporary storage and concentration until defacation o Accessory organs Pancreas Makes enzymes and hormones The acini tissue o Secrete enzymes into GI tract Zymogens Pancreatic amylase Pancreatic lipase Islet tissue o Secrete hormones into the blood Beta cells insulin Alpha glucagon Delta somatostatin o Not connected to the GI Liver Makes bile o Emulsifeier for fats required for fat digestion o Made in hepatocytes from cholesterol o Stroed in gallbladder o After digestion of fats bile is reabsorbed in ileaum and sent back to the liver by the EHC Metabolized drugs alcohol and other toxins Makes plasma proteins Site of urea synthesis o Albumin Major transport protein Maintains osmotic pressure Low albumin allows for fluid to leave bloodstream and pool in intercellular spaces edema o Transferrin which transports iron o Makes lipoproteins which carry cholesterol and transport fat soluble vitamins A D E and K Liver gets first pass at all nutrients in the body when we eat o The vascular system carries nutrients in blood to liver and then disperses it to the body EHC Lymph system carries exogenous lipids and they go into the bloodstream at the thoracic ducts Digestion of carbs o Major source of energy fuel in the diet o Approx 1 2 of total caoric intake is in the form of carbhohydrates We have polysaccharides and simple sugars o Glycogen is stored glucose liver and muscle o Different types of monosacharrides Depends on number of carbons Triose Tetrose Pentose o Made from hexose o Make ATP DNA and RNA Hexose glucose galactose fructose o We get energy from hexose sugars Heptose o Glucose Most abundant monosaccharide called blood sugar Where bonds are tells you the structure of the molecule o Disaccharise are 2 monosaccharied form from condensation Glucose glucose maltose Glucose galactose lactose Milk sugar Glucose fructose sucrose Table sugar o High fructose corn syrup Its man made not natural 2 types 45 glucose and 55 fructose o from corn and used in processed food o gives food linger shelf life and o cane sugar and beet sugar o oligosaccharides 3 10 monosaccharides not digested in small intestine they go to large intestine and fibers found in beans peas whole bran are fermented by bacteria o polysaccharides starch storage form of carbs in plants amylose o linear molecule o alpha 1 4 bonds of repeating glucose chains amylopectin o branches chain o alpha 1 4 bonds straight chain and alpha 1 6 glycogen branches storage form of carbs in animals stored in liver and muscle highly branched we get energy from it from glycogenolysis breaking down of glycogen total muscle glycogen more glycogen but liver holds most glycogen from a single source fiber non digestible plant polysaccharides different types defined my the USDA o dietary fiber naturally occurring o functional fiber fiber added to food onsiluble fiber o does not dissolve in water o decreases transit time and increases fetal bulk o lignans celluloses and some hemicelluloses soluble fiber o dissolves in water o increases transit time o pectins gums some hemicelluloses fiber is digested in large intestine by bacteria it is NOT enzymatically digested o hydrogane methane gasm CO2 SCFA are by products o SCFA Stimulates water and sodium absorption into mucosa Without these we would get diarrhea Provide colanocytes with energy Increase immune function by increasing immune cells and increasing good bacteria Decreases atrophy of the gut When cells atrophy they get smaller and let nutrients through without being processed into the cell decreases cholesterol by decreasing pH which
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