Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download An amazing journey through the digestive tract! Learn underlined
Document related concepts
Transcript
An amazing journey through the digestive tract! Learn underlined terms! Italicized terms are common disorders that can occur. Accessory organs are in the dashed box. (Bold is just for clarity.) Organ Food Passes Through Mouth & Salivary Glands Epiglottis Esophagus GastroEsophageal Sphincter Stomach Mechanical Action Secretions & Flora Action of the Chemicals Involved Saliva: Water: Moistens food Salivary Enzymes: Start starch & fat breakdown Teeth chew up food into smaller pieces Bolus is swallowed Closes over trachea (airway) Peristalsis (rhythmic muscle contractions) pushes bolus along Opens to stomach Closes to prevent backflow Churns food with Gastric juice: secretions into Water: Liquifies food liquidy chyme Hydrochloric Acid: Denatures pro, kills bacteria, achieves ideal pH for enzymes Gastric Enzymes: Partial pro breakdown & a little fat breakdown Mucus: Protects stomach walls Intrinsic Factor: Attaches to Vit B12 Pyloric Sphincter Opens to let chyme (or Valve) slowly enter the small intestine Closes to prevent backflow © updated 2008 by Michele McMullen What’s Absorbed Here? What could go wrong? Painful chewingPEM (Eating too fast Belching & Hiccups) Choking Dysphagia Vomiting (reverse peristalsis) Other fascinating facts Esophagus passes through hiatus--an opening in the diaphragm Gastric reflux (GERD) & Heartburn Diabetic Gastroparesis Stomach absorbs: Some Glucose Some ETOH Excess water Gastritis & Ulcers Presence of food makes stomach wall cells produce hormone gastrin stomach gland cells make acid & to keep pH around 1.5. Most ulcers are due to H.pylori infections B12 deficiency Opening & closing is regulated by pH of chyme & caloric density of meal Organ Food Passes Through Small Intestine (which includes the Duodenum, Jejunum & Ileum) Mechanical Action Secretions & Flora Chemical Action Involved Peristalsis & Bile: (made in Liver; Emulsifies fat into Segmentation: stored in Gallbladder; digestible particles squeezes chyme into released into & used segments; allows in small intestine) better mixing & absorption Pancreatic juice: Bicarbonate: Neutralizes stomach acid Villi movements further stir chyme up to expose surface area Pancreatic Enzymes: Breakdown of polysaccharides, pro, fat Crypts secrete Intestinal Enzymes: Breakdown of disaccharides, di/tripeptides & fat fragments Intestinal Flora: Fight foreign bacteria; make some vits Mucus: Protects intestinal walls What’s Absorbed Here? What could go wrong? Gallbladder disease Other facts Pancreatitis Acidic chyme makes duodenal cells release secretin stimulates pancreas to release bicarbonate Absorbed in Duodenum: Monosaccharides & Some minerals Lactose intolerance Absorbed in Jejunum: Vits, aa, monosaccharides & monoglycerides, glycerol, fa, rest of ETOH Absorbed in Ileum: Vit B12 & Bile salts Ileocecal Valve Large intestine (aka colon or bowel) Opens & closes Peristalsis & Segmentation Rectum Anus Stores waste Keeps rectum closed until elimination Intestinal Flora: Fight foreign bacteria; make some vits; digest some fiberSCFA & gas (Most fiber remains & provides bulk) Absorbed in Colon: Water, minerals (lytes), Vit K, SCFA (from flora) Diverticulitis; Constipation; Colitis; IBS; Gassiness Hemorrhoids Fat makes duodenal cells release CCK Stimulates gallbladder to release bile The pancreas adjusts the amts of various digestive enzymes it makes based on usual amts of CHO, pro, and fat in diet Due to mucosal folds, villi & microvilli, the absorption area in the small intestine is HUGE!! Much of the total volume of feces is dead bacteria. Ick!
