Digestive Processes PowerPoint presentation prepared by: Shanta Adeeb Digestive Processes 1. 2. 3. 4. Mechanical Breakdown (Ingestion) Digestion Absorption Excretion Mechanical Breakdown Mostly in the mouth. Also in the stomach The first of the four stages Digestion Breaks down food into molecules small enough to be absorbed Proteins to peptides and amino acids Complex carbohydrates to simple sugars Lipids to fatty acids Absorption Nutrients are taken up by cells that line the digestive tract Different nutrients are taken up at different rates Nutrients are converted to energy that may be immediately used or stored Fat Glycogen Excretion The last stage of food processing in the body Undigested wastes pass out of the digestive tract Role of insoluble fiber and water Digestive Components Processes take place in specific organs: Mouth Esophagus Stomach Small Intestine Large Intestine Mouth Food enters and is reduced in size by teeth and tongue Salivary glands secrete saliva, which lubricates and buffers food (bolus), amylase (enzyme) starts starch digestion Esophagus Food passes through on its way to the stomach No functional role, it’s just a pipe Stomach Stores and digests food One quart (4 cup) capacity – can be stretched Food retention is 2 to 3 hours at capacity Stomach Mucus produced protects lining from acid Ulcers are caused by a specific bacterium, Hilobacter pylori Secretes hydrochloric acid (HCl) Produces enzyme pepsin (protein digestion) Small Intestine 10 ft long Very large surface area ~200 m2 (15 x 15 yards) due to villi and microvilli Retains food 3 to 10 hours Small Intestine Receives enzymes from pancreas Site of most digestion and absorption Large Intestine 3 ½ ft long Retains food up to 72 hours (less w/ insoluble fiber). (72 h is not good.) “The beet test.” “The beet test” Learning objective: Student will gain experiential understanding of “intestinal transit time.” Was once amusing, not it’s just gross. Other Components Esophageal sphincter: blocks acid reflux Liver: produces bile salts which emulsifies fats Other Components Gallbladder: stores bile salts Pancreas: secretes digestive enzymes and insulin VIDEO (Can read full screen from web site This is an excellent review. Food industry addresses supplement issues using country specific marketing tools. Sex sells both here and aboard.