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Learn about the process of digestion, from the mechanical and chemical breakdown of food in the mouth to the absorption of nutrients in the small intestine. Explore the role of accessory organs and common digestive disorders.
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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 • 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 • ***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 • 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