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 Breaking down of food into smaller pieces The mixing of food The mixing of food Movement through the digestive tract Movement through the digestive tract Chemical breakdown of the large molecules of food into smaller molecules. Chemical breakdown of the large molecules of food into smaller molecules.

3. Two Types of Digestion Mechanical – physically changing the size of food 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 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 a series of hollow organs that food passes through Also known as the alimentary canal Also known as the alimentary canal –Alimentary: of or relating to nourishment or nutrition

5. Identify the organs of the digestive system

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

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

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

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

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

12. Esophogus peristalsis 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://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapter26 /animation__organs_of_digestion.html http://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapter26 /animation__organs_of_digestion.html 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%20Biolog y/digestive/danatomy/images/peristalsis.gif

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

14. Stomach Chemical digestion: 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/hwk b17_010.jpg

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

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

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

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

19. Rectum and Anus Rectum = store the feces. Rectum = store the feces. Anus: ring of muscle that squeezes the feces out of the body. 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 Aid (help with) in digestion but food never travels through Liver, Pancreas, Gall bladder Liver, Pancreas, Gall bladder

21. Liver The liver is like a processing factory with more than 200 different jobs. 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 Produce insulin and enzymes Enzymatic juices travel through the common bile duct into the small intestine 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. A small baglike sac under the liver. It stores bile. It stores bile. Empties the bile into the small intestine via the common bile duct 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 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 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. 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. 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. 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. 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/dig est_noSW.html http://kidshealth.org/kid/body/dig est_noSW.html