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The Digestive System

The Digestive System. Digestion is the process of breaking down food into molecules the body can use. How is food digested?. Digestion involves: Breaking down of food into smaller pieces The mixing of food Movement through the digestive tract

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The Digestive System

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  1. The Digestive System Digestion is the process of breaking down food into molecules the body can use

  2. How is food digested? Digestion involves: • Breaking down of food into smaller pieces • The mixing of food • Movement through the digestive tract • Chemical breakdown of the large molecules of food into smaller molecules.

  3. Two Types of Digestion • Mechanical – physically changing the size of food • Ex: grinding action of teeth • Ex: churning action of stomach • Chemical – a change in the chemical nature of the nutrients • Ex: amylase (in saliva) working on starch

  4. Gastrointestinal Tract • a series of hollow organs that food passes through • Also known as the alimentary canal • Alimentary: of or relating to nourishment or nutrition

  5. Identify the organs of the digestive system

  6. Identify the organs of the digestive system

  7. Mouth (oral cavity) Teeth -mechanical digestion • Chemical Digestion: • Amylase Enzymes in saliva chemically digest carbohydrates.

  8. Mouth (oral cavity) Tongue: • Keeps food in place • Push bolus to back of mouth • Bolus: a soft mass of chewed food

  9. Uvula Dangling“thing” in back of throat Catches bacteria and dirt particles Can be destroyed by bulimics More to the Mouth

  10. Open area at back of the mouth Passageway for both food & air Epiglottis – thin flap that prevents food from entering the trachea Pharynx http://www.cortexity.com:8080/nicksblog/images/pharynx.jpg

  11. Tube about 25cm long connects the pharynx to the stomach. 2 layers of muscle. Esophagus http://www.massgeneral.org/cancer/crr/types/thoracic/illustrations/images/esophagus_front.jpg

  12. Esophogus • peristalsis • Wavelike, involuntary muscle contractions that pushes food through the digestive tract • http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter26/animation__organs_of_digestion.html http://www.easttroy.k12.wi.us/hs/dept/science/bottum/Adv%20Biology/digestive/danatomy/images/peristalsis.gif

  13. Both mechanical and chemical digestion Mechanical Digestion 3 layers of muscle that twist and turn the stomach Results in churning action = mechanical Makes your stomach “growl” Stomach

  14. Stomach • Chemical digestion: • Stomach lining produces HCl (hydrochloric acid) to breakdown and dissolve nutrients • Enzyme – Pepsin begins to digest proteins • Bolus becomes Chyme http://www.health.com/health/static/hw/media/medical/hw/hwkb17_010.jpg

  15. Small Intestine • 7 meters long (22feet) • Site of nutrient diffusion into blood from mesentary http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/19221.jpg

  16. Small Intestine • Mesentary: • Contains blood vessels that Absorb the nutrients

  17. Large Intestine • Water and Minerals (NaCl) are absorbed back into the blood • The remains are formed into brown, semi-solid feces

  18. Large Intestine • Diarriaha • Water was not reabsorbed • Constipation • Too much water was reabsorbed

  19. Rectum and Anus • Rectum = store the feces. • Anus: ring of muscle that squeezes the feces out of the body.

  20. Accessory Organs • Aid (help with) in digestion but food never travels through • Liver, Pancreas, Gall bladder

  21. Liver • The liver is like a processing factory with more than 200 different jobs. • Produces bile • Bile: breaks down fats in the small intestine. • Stores some nutrients • brought from the blood after the small intestine • Produces cholesterol • Detoxifies

  22. Pancreas • Produce insulin and enzymes • Enzymatic juices travel through the common bile duct into the small intestine http://www.fairview.org/healthlibrary/content/pancreas.gif

  23. Gall Bladder • A small baglike sac under the liver. • It stores bile. • Empties the bile into the small intestine via the common bile duct

  24. Common Bile Duct • Collects from liver, gallbladder, pancreas and empties into the small intestine

  25. To quiz yourself over the parts of the digestive system, click here: http://www.tvdsb.on.ca/westmin/science/sbi3a1/digest/digdiag.htm

  26. Describe water • Most of the nutrients in your body can't be used unless they are carried in a solution. This means that they have to be dissolved in water. • In cells, chemical reactions take place in solutions.

  27. Describe water • Most of the material absorbed from the cavity of the small intestine is water in which salt is dissolved. • The salt and water come from the food and liquid we swallow and the juices secreted by the many digestive glands.

  28. For more information about the digestive system, click here: http://kidshealth.org/kid/body/digest_noSW.html

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