Transcript DIGESTION
DIGESTION MOUTH Mechanical Digestion • Teeth break down food Chemical Digestion • Enzymes in the mouth break down food Ex. Salivary amylase ESOPHAGUS Tube that leads from the mouth to the stomach. • Peristalsis contractions of the smooth muscle that lines the esophagus cause food to move down EPIGLOTTIS At the back of your throat is your windpipe (trachea), which allows air to come in and out of your body. When you swallow a flap called the epiglottis flops down over the opening of your windpipe to make sure the food enters the esophagus and not the trachea. STOMACH STOMACH A muscular sac Has GASTRIC GLANDS that secrete HCl (Hydrochloric Acid) and pepsin Has mucus to protect the lining. Main site of protein digestion The stomach’s partially digested food is called CHYME SMALL INTESTINE SMALL INTESTINE ***Digestion is completed in the small intestine.*** About 22 ft long Main site of lipid digestion Has intestinal glands that make enzymes VILLI Small intestine is lined with villi that absorb nutrients and diffuses them into the blood stream ACCESSORY ORGANS THAT HELP THE SMALL INTESTINE Pancreas • Secretes “juices” which help digestion Ex. Amylase, Lipase, Protease ACCESSORY ORGANS THAT HELP THE SMALL INTESTINE Liver • Makes bile Bile MECHANICALLY breaks down fats (emulsifies) ACCESSORY ORGANS THAT HELP THE SMALL INTESTINE Gallbladder • Stores bile and sends it through the bile duct into small intestine LARGE INTESTINE/COLON LARGE INTESTINE/COLON About 5 ft long Water is absorbed here Some vitamins are absorbed here Undigested material is egested (defecation) DISORDERS Acid Reflux/Heartburn • The lower esophageal sphincter is just before the opening to the stomach • This sphincter opens to let food pass into the stomach and closes to keep it there. • If your L.E.S. doesn’t work properly, the stomach acid may come back up into the esophagus. Ouch! DISORDERS Constipation/Diarrhea • If the large intestine absorbs too much water from the undigested material = constipation. • If the large intestine does not absorb enough water from the undigested material = diarrhea. DISORDERS Ulcers • A sore in the lining of the stomach or upper small intestine • Develop when the stomach’s protective layer is broken down Digestive juices can damage the intestine or stomach tissues, as well as the esophagus Don’t forget, gastric juices contain hydrochloric acid! DISORDERS Appendicitis • Your appendix is inflamed May have to be removed DISORDERS Gall stones • Hard particles of cholesterol that can block the bile duct REPRESENTATIVE ORGANISMS Amoeba • 1. pseudopods Ingestion by phagocytosis • 2. vacuole Storage • 3. lysosome Has enzymes to digest As lysosome breaks down, nutrients are absorbed into cytoplasm • 4. egestion across cell membrane REPRESENTATIVE ORGANISMS Paramecium • 1.oral groove Cilia “sweep” food to oral groove • 2.vacuole storage • 3. lysosome Breaks down food and nutrients are absorbed into cytoplasm • 4. anal pore Undigested material is egested REPRESENTATIVE ORGANISMS Hydra • 1. tentacles Have stinging cells Help to “sweep” food into mouth • 2. mouth/site of egestion Food comes into and out of same area • 3. gastric cavity Digestion Cells in lining secrete enzymes REPRESENTATIVE ORGANISMS Earthworm • **tube within a tube digestive tract** 1. mouth • Uses sucking action to pull food in 2.esophagus • Pulls food into crop 3. crop • Storage chamber 4. gizzard • Thick walled muscle that MECHANICALLY crushes food 5.intestine • Enzymes break down food • Absorption 6. anus REPRESENTATIVE ORGANISMS Grasshopper • 1. mouth Mechanical and chemical digestion • 2. crop Temporary storage • 3. gastric area/gizzard Thick muscular walls of teeth-like plates (chitin) that break food into smaller pieces • 4. stomach Chemical digestion by enzymes • 5. intestine Connects stomach to anus • 6. anus Has rectum for storage and re-absorption of water