nutr chapter 4

• digestive system consists of mouth, esophagus, stomach, intestines, and the accessory organs
• mouth and salivary glands prepare food for swallowing, detect taste, start digestion with anylase and lingual lipas
• esophagus moves food to stomach by peristaltic wavs initiated by swallowing
• stomach secretes gastric juices containing acid, enzymes, and hormones which mixes with food and turns it into chyme then kills microoganisms with acid
• liver- produces bile to aid fat digestion and absorption
• gallbladder- stores and concentrates bile and releases it to the small intestine
• pancreas- secretes pancreatic juices containing digestive enzymes and bicarbonate into the small intestine
• small intestine- mixes chyme with bile and pancreatic juice and does most of the absorption then transports remaining residue to large intestie
• large intestine (colon)- absorbes water and electrolytes and forms and stores feces
• rectum- holds and expels feces via the anus
• gi wall has 4 layers 1. mucosa 2. submucosa 3. muscle 4. serosa
• lower esophogeal sphincter- prevents reflux of stomach into esophagus
• pyloric sphincter- control flow of stomach contents into small intestine
• swallowing- epiglottis cloes over the larynx to prevent food from entering the trachea
• 1. stomach- food enters stomach via the lower esophageal sphincter. little digestion happens here the stomach is mainly just a holding tank. it secretes gastric juices that contain hydrochloric acid, pepsinogen (digests protein), and gastrin which helps control the release of hci and pepsinogen. also secretes mucus that lubricate and protect stomach and lining from hci. nsaids inhibit prostaglandins productions of mucus
• 2. small intestine is divided into three sections duodenum, jejunum, ileum. inside has circular folds and villi that help move food along. villi are lined with enterocytes that secrete enzymes and absorb nutrients
• digestion in the small intestine depends on secretions from the accessory organs
• secretions from the ao's are delivered through the common bile duct and pancreatic duct
• liver produces bile that contains cholesterol and emulsifies fat
• gallbladder stores and concentrates bile
• pancreas produces sodium bicarb (neutralizes acidic chyme) pancreatic lipase (digests fats) pancreatc amylase (digests starch) proteases digest (proteins)
• 5 main hormones in regulation of digestive processes are gastrin, secretin, cholecystokinin (cck), somatostatin, and glucose dependent insulinotropic peptide (gip)
• ghrelin- increases appetite and food intake
• gastrin- triggers the stomach to release hci and pepsinogen and stimulates gastric and intestinal motility
• somatostatin- inhibits release of gi hormones, slows gastic emptying, gi mobility, and blood flow
• passive diffusion- nutrients move from an area of low concentration
• facilitated diffusion- high to low w help
• active transport- low to high w help
• 3. large intestine- small intestine empties into large through the ileocecal valve. has 3 main parts colon, rectum, and anus. 3 main functions are to house microbiota, absorb water and electrolytes, and to form and expel feces
• probiotics- LIVE microorganism that colonize the large intestine and prevent diarrhea, food allergies, ibs, ibd
• prebiotics- non-digestible food ingredients that promote the grown of beneficial bacteria
• gerd- 2 or more times a week of heartburn and acid reflux
• ulcers are caused by helicobacter pylori and heavy use of nsaids
• ibs- unknown cause. irregular bowel function, abdominal pain, bloating