1 / 23

Digestive System

Digestive System. What is digestion?. Digestion is the conversion of food into small substances that are useful to your body carbohydrates  monosaccharides protein  amino acids lipids  fatty acids & glycerol Takes place in mouth (oral cavity) & stomach. Digestive System. Parts.

Download Presentation

Digestive System

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.


Presentation Transcript

  1. Digestive System

  2. What is digestion? • Digestion is the conversion of food into small substances that are useful to your body • carbohydrates  monosaccharides • protein  amino acids • lipids  fatty acids & glycerol • Takes place in mouth (oral cavity) & stomach

  3. Digestive System Parts Mouth Pharynx Esophagus Stomach Small Intestine Large Intestine Anus • aka. gastrointestinal tract or alimentary canal • Contains accessory organs • i.e. salivary glands, pancreas, liver, gall bladder • Provide enzymes needed for digestion

  4. Types of Digestion • Mechanical • Occurs in mouth & stomach • Involves tearing, chewing, grinding, peristalsis • Chemical • Occurs in mouth, stomach, small intestine • Food is coated with saliva which contains digestive enzymes that break down food

  5. Parts & Functions DIGESTIVE SYSTEM

  6. OralCavity PARTS • Teeth • Tongue • Salivary glands • Pharynx

  7. Oral Cavity: Teeth • Carnivores • Enlarged canines for biting & tearing meat • Herbivores • Premolars & molars used to grind & crush rough fibrous plants • Incisors angled for cutting • Ominvores • Eat plants & animals so their teeth resemble both carnivores & herbivores

  8. Oral Cavity: Saliva • a fluid/ secretion from the salivary glands • made of digestive enzymes • i.e. amylase  breaks down carbohydrates • Function: to lubricate & breakdown food

  9. Oral Cavity: Tongue • Tongue manipulates food during chewing • Helps food form the bolus • Pushes food back to molars for grinding

  10. Oral Cavity: Bolus • Bolus = moist ball of food • Easy to swallow b/c it is lubricated • Does not damage esophagus lining & digestive tract • Digested bolus = chyme • Movement of bolus: • Tongue • Roof of mouth • Pharynx • Epiglottis • Esophagus

  11. Esophagus • Muscular • Diameter = 2 cm • Connects pharynx & stomach • Cardiac (lower esophageal) sphincter prevents food from going back up the esophagus • Food moves by peristalsis • Wave like muscle contractions that push food along

  12. Stomach • What type of digestion takes place in the stomach? • Mechanical: churning • Chemical: gastric juices contain enzymes that breakdown food • Gastric juices are made of HCl & pepsinogen • pH of stomach = 2 • Enzymes in the stomach: pepsin & renin • Pepsin breaks down proteins into a.a. • Renin slows down movement of milk to allow proper digestion

  13. Stomach • Pepsinogen • Pepsinogen = inactive pepsin • Pepsin causes proteins to be broken down into a.a  • Hydrochloric Acid (HCl) • Secreted from gastric glands • Sterilizes upper digestive tract & destroys invading microbes • causes the stomach to have a low pH which is optimum pH for pepsin to function • mucous, secreted by mucous cell or gastric gland, protects stomach from HCl

  14. Small Intestine • Site of digestion & absorption • 6 m long • Smaller in diameter than large intestine • Secretes intestinal juices • Receives intestinal secretions from pancreas & liver • Ileocaecal valve separates small intestine from large intestine

  15. Small Intestine • What is intestinal absorption? • Nutrient absorption through walls of small intestine • Uses active & passive transport Nutrients  intestinal wall  liver  blood  body

  16. Small Intestine: Absorption • Villi • Found in the small intestine • 80% of absorption occurs here • are projections of the mucosa into the lumen • Increase surface area for absorption • Why are the villi nestled within capillaries? • For quick absorption of nutrients into blood stream for distribution around body

  17. Large Intestine • Function: reabsorption of water, salts, some vitamins • Parts: • Caecum: receives material from small intestine • Colon: ascending, transverse, descending • Rectum: Feces passes through here • Anus:Feces exits here

  18. Large Intestine • Chyme enters caeccum near appendix • Appendix was part of lymphatic system • Microorganism that live here help body • i.e. absorption of vitamin K • Feces/stool: final product leaves body from here

  19. Factoids • HOW LONG ARE YOUR INTESTINES? At least • 25 feet in an adult. • Be glad you're not a full-grown horse -- their coiled-up intestines are 89 feet long • It takes 3 hours for food to move through the intestine • In your lifetime, your digestive system may handle about 50 tons!!

  20. Animations • http://www.medtropolis.com/VBody.asp • http://www.tvdsb.on.ca/westmin/science/sbi3a1/digest/digdiag.htm • http://www.pennhealth.com/health_info/animationplayer/

  21. Assignment • TB: Read chapter 3 pages 97 to 99 • Course Package B 25 to B27

More Related