The Digestive System

1. The Digestive System

2. Homework • Chapter 6.3 – Practice Problems 1-3 • Section 6.4 – Practice Problems 1-5 • Section 6.5 – Practice Problems 1-6 • Copy Figure 2 (p. 217) into your notes in your own words • Copy Figure 3 (p. 217) into your notes.

3. This week • Today – Powerpoint Digestive System • Tuesday – Quiz (Label the Dig. System) • Villi, Absorption, Proteins, Carbs and Lipids • Extra Help After School • Wednesday – Review • Thursday – Worm Overview/ Test Review Sheets • Friday – Worm Lab • Sunday – Extra online help • Monday – Unit Test

4. 4 Functions of the digestive system • INGESTION • DIGESTION • ABSORPTION • EGESTION

5. Digestion • Starts in the mouth • Ends in the anus • Food can be broken down mechanically (chewing) and chemically (with enzymes) to be digested (broken down).

6. Absorption • Digested food into the bloodstream through the walls of the small intestine. • Cells burn the energy (sugar, fatty acids, and amino acids) in the presence of oxygen to release stored energy within the food.

7. Absorption • Cells also use larger proteins to help build larger protein molecules needed for growth and development.

8. Elimination • The digestive system eliminates materials that cannot be used in the body via elimination. • The large intestine concentrates these solid wastes, called FECES, and finally the waste passes out of the body through the anus.

9. Inside the Oral Cavity • The gastrointestinal tract (GI tract) begins with the oral cavity. • Oral (or/o = pertaining to the mouth) • The cheeks form the walls of the oval shaped oral cavity, and the lips surround the opening of the cavity. • The hard palate form the anterior portion of the roof of the mouth. • The soft palate consists of the muscular membrane that lies posterior to it.

10. The Oral Cavity

11. The Oral Cavity • The uvula is the small tissue projection that hangs from the soft palate (hangy ball) • The uvula helps with the production of the sounds of speech. • The tongue covers the floor of the oral cavity, aids in moving the food during mastication (chewing) and deglutition (swallowing). • Ruage are the bumps on the top of the hard palate.

12. The Oral Cavity

13. The Oral Cavity • Papillae, small raised bumps on the tongue, contains taste buds. • Sensitive to food chemicals and allow discrimination of different tastes as the food moves across the tongue.

14. Papillae • Some people think that every bump on their tongue is, itself, a taste bud, but that is NOT true.  • Each papillae has many taste buds within it.  • In addition, we have taste buds that are not even on our tongues.  • Some taste buds are found in our throats, cheeks, and in the roof of our mouths.

15. Papillae

16. Taste Regions

17. Tonsillitis

18. The Oral Cavity • The gums are fleshy tissue that surrounds the sockets of the teeth. • The adult human has 32 teeth (16 permanent teeth top/16 bottom arch). Central incisor (1) Lateral incisor (2) Canine (3) First premolar (4) Second premolar (5) First molar (7) Third Molar (wisdom tooth) (8)

19. Salivary Glands • 3 pairs in the oral cavity • Produce Saliva, that contain digestive enzymes. • Saliva is released from the parotid gland, submandibular gland and sublingual gland on EACH side of the mouth. • Narrow ducts carry saliva into the oral cavity.

20. The Oral Cavity • Together the teeth and saliva breakdown food in the oral cavity.

21. Components of the Digestive System • Esophagus • Stomach • Small Intestine • Large Intestine • Gall bladder • Liver • Pancreas

22. Esophagus • the tube that connects your mouth and your stomach

23. Esophagus • Muscular tube • 9-10 inches from the pharynx to the stomach • Peristalsis is the involuntary, progressive, rhythmic contraction of muscles in the walls of the esophagus (and other gastrointestinal organs) propelling a bolus(mass of food) toward the stomach.

24. Food Passage thus far • Oral cavity (teeth, tongue, saliva) • Pharynx • Esophagus • Stomach

25. Stomach • A stretchy bag that holds your food after you eat • Helps to break food into smaller pieces so your body can use it for energy and nutrition

26. Esophagus Stomach

27. The Stomach • From the esophagus into the stomach • 3 parts: Fundus (upper portion) Body (middle section) Antrum (lower portion) FUNDUS ANTRUM BODY

28. Inside the Stomach • Folds in the lining of the stomach are called rugae. • The rugae contain digestive glands that produce the enzyme pepsin (to begin digestion of proteins) and hydrochloric acid. • Food leaves the stomach in 1 to 4 hrsor longer, depending on the type/amount of food eaten.

29. Sphincters • Rings of muscles • Control the opening and closing of the stomach • Lower esophageal sphincter (cardiac sphincter) relaxes and contracts to move food from the esophagus to the stomach. • Pyloric sphincter allows food to move from the stomach to the intestine.

30. Small Intestine • Tube that is 20 feet long. • Continues to digest food • Food stays in your small intestine for 4 to 8 hours

31. Small Intestine

32. Small Intestine • 20 feet from the pyloric sphincter to the first part of the large intestine. • 3 parts of the small intestine: • 1. DUODENUM • 2. JEJENUM • 3. ILEUM

33. The Small Intestine • Lined with VILLI • Tiny microscopic projections • Microscopic blood vessels in the villi absorb the digested nutrients into the bloodstream and lymph vessels.

34. Duodenum • 1 foot long • Receives food from the stomach • Bile from the liver • Bile from the gallbladder • Pancreatic juice from the pancreas • Enzymes and bile help digest food before it passes to the second part of the small intestine.

35. Large Intestine • Tube that is 5 feet long • Gets waste from small intestine • Waste stays for 10 to 12 hours

36. The Large Intestine • Receives the fluid waste from digestion (the material that is unable to pass into the bloodstream). • It stores the waste until they can be released from the body.

37. Large Intestine

38. Large Intestine • From the small intestine to the anus • 6 sections • The APPENDIX hangs from the large intestine. • The appendix has no clear function but can become inflammed and infected when clogged or blocked. • Thought to be involved with breakdown of plants during primitive life.

39. Large Intestine Sections

40. The Large Intestine • Absorbs water within the waste material allowing the body to expel solid feces (stools). • Defecation is the expulsion or passage of feces from the body through the anus. • Diarrhea, or watery stools, results from reduced water absorption into the bloodstream through the walls of the large intestine.

41. Gall Bladder • Storage tank for bile (a greenish-yellow liquid) that helps your body break down and use fats • Located under your liver • Shaped like a pear

42. Gall Bladder

43. Gallbladder • Pear-shaped sac • Stores and concentrates bile for a later use. • After you eat the gallbladder contracts, forcing the bile into the cystic duct into the common bile duct.

44. Liver • Factory for antibodies and bile • Stores vitamins and sugars until your body needs them

45. The Liver • Produces BILE (a thick, orange-black, sometimes greenish fluid). • Bile contains cholesterol (a fatty substance), bileacid, and bile pigments. • Bilirubin – produced from the breakdown of RBCs in normal RBC destruction. • Bilirubin travels to the liver through the bloodstream, where it is conjugated with another substance and added to bile. • Bilirubin enters the intestine with bile. • Bacteria in the colon breakdown bilirubin into pigments that gives feces its brown color. • Bilirubin and bile leave the body in feces.

46. Liver

47. Other Functions of the Liver • Maintain proper sugar levels (glucose) • Manufacture blood proteins (blood clotting) • Releasing Bilirubin, a pigment in bile • Remove Poisons (toxins) from the blood.

48. Jaundice • Occurs when bilirubin can’t leave the body. • Causes a yellowish discoloration of the skin, whites of the eyes, and mucous membranes.

49. Pancreas • Helps you digest food by breaking down sugars

50. Functions • Digest the food we eat • Take the nutrients out of your foodso your body can use it