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  • 1. Digestion Master Traithana ChaowanapreechaMaster Alfredo V. Garcia III
  • 2. DefinitionDigestion the process of breaking down food particles (macromolecules) into smaller, simple molecules that can be absorbed into cells or the bloodstream. EnzymesExamples: Enzymes Starch Glucose Protein Amino acids
  • 3. The digestion of different organisms
  • 4. The digestion of different organisms1. Intracellular digestion food is taken into cells by phagocytosis forming a food vacuole, then lysosome fuses the vacuole and releases enzymes to digest food. Food molecules are absorbed to cytoplasm. Waste is expelled by exocytosis.Examples: Amoeba, paramecium, other
  • 5. Intracellular digestion
  • 6. The digestion of different organisms2. Extracellular digestion organisms secrete enzymes out of their cells. Food is digested and absorbed into cells.Examples: Bacteria, fungi, most animals including humans
  • 7. The digestion of different organisms2 methods to digest:1. Mechanical digestion Food is broken into smaller pieces by chewing, contracting muscles (peristalsis of intestines and a stomach). Food can bind to enzymes better.2. Chemical digestion Macromolecules are broken down into smaller molecules
  • 8. Digestive systems of different organisms
  • 9. Digestive systems of different organismsA sponge has choanocytes engulfing food into cells and
  • 10. Digestive systems of different organismsCoelenterates have a gastrovascul ar cavity, the digestion zone.
  • 11. Digestive systems of different organisms A nematode has a complete digestive system including mouth, esophagus, intestine, and anus.
  • 12. Digestive systems of different organismsAn earth worm also has a completedigestive system including mouth,esophagus, crop, gizzard, intestine,and anus.
  • 13. Digestive systems of different organismsAn insect has a crop storing foodand a gizzard digesting food.
  • 14. Digestive systems of different organismsA birds digestive system has beak and mouth suitable for different kinds of food, esophagus, crop, stomach, gizzard, intestine, rectum and cloaca.
  • 15. Digestive systems of different organismsHerbivorous mammals likes cowsand buffaloes have 4-chamberedstomach suitable for cellulosedigestion.
  • 16. Digestive systems of different organisms Carnivorous animal digestive system
  • 17. Digestive system of a human
  • 18. Human digestive systemAlimentary canalMouth pharynx esophagus stomach-Teeth-Tongue large intestine -Duodenum -Ascending colon -Transverse colon -Jejunum small intestine -Descending colon -Ileum rectum anus
  • 19. Human digestive systemDigestive glands- Salivary glands- Gastric glands- Intestinal glands- Pancreas- Liver
  • 20. Human digestive systemDigestion in the oral cavityOral cavity includes upper jaws, lower jaws, teeth, gum, cheek lining, hard and soft palates.Mechanical digestionTeeth cut, tear, and grind food into small pieces, then a tongue mixes food with saliva secreted from 3 pairs of salivary glands (sublingual, submandibular, and parotid).
  • 21. There are 2 sets of human teeth formed by ectoderm.- Deciduous teeth, D.T., are firstly formed at age 6 months and start to fall out at 6 years old. There are totally 20 D.T.- Permanent teeth, P.T., are completely formed at age 13. There are totally 32 P.T.
  • 22. 32 Human permanent teeth include:1. 4 upper incisors cut food (well- developed in rodents) 4 lower incisors2. 2 upper canines cut, tear, and separate food 2 lower canines (well-developed in carnivores)3. 4 upper premolars cut and tear food 4 lower premolars (well-developed in carnivores)4. 6 upper molars chew and grind food
  • 23. Salivation is controlled by parasympathetic nervous system (cranial nerve pairs no.7 and 9)Stimuli: seeing food, smelling, tasting, toughts amylaseChemical digestion amylaseStarch + water dextrinDextrin + water maltose
  • 24. How is food transferred from a mouth to a stomach?Food travels along esophagus to a stomach by peristalsis (muscle contractions: the waves of involuntary muscle contractions that transport food, waste matter, or other contents through a tube-shaped organ.)
  • 25. Digestion in a stomach- Capacity when its empty = 50 100 mL- Capacity when its full = 1-2 LEpithelial cells line inner surface of the stomach and secrete about 2 liters of gastric juices per day. Gastric juice contains hydrochloric acid, pepsinogen, rennin, lipase, potassium chloride, and mucus; ingredients important in digestion.
  • 26. Secretions are controlled by nervous (smells, thoughts, and caffeine) and endocrine signals.The stomach secretes hydrochloric acid and pepsin. Hydrochloric acid (HCl) lowers pH of the stomach so pepsin is activated. Pepsin is an enzyme that pepsin controls the hydrolysis of proteins into peptides. The stomach also mechanically churns the food.Protein short polypeptides
  • 27. Anatomy of the StomachLocated on the left side of the body, under the diaphragm, the stomach is a muscular, saclike organ that connects the esophagus and small intestine. Its main function is to breMicrosoft Encarta Reference Library 2003. 1993-2002 Microsoft Corporation. All rights reserved.
  • 28. UlcersPeptic ulcers result when these protective mechanisms fail. Bleeding ulcers result when tissue damage is so severe that bleeding occurs into the stomach.Perforated ulcers are life-threatening situations where a hole has formed in the stomach wall. At least 90% of all peptic ulcers are caused by Helicobacter pylori. Other factors, including stress and aspirin, can also produce ulcers.