The Digestive System

1. The Digestive System

2. 3 Functions of the digestive system • DIGESTION • ABSORPTION • ELIMINATION

3. 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).

4. Absorption • Digested food enters 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.

5. 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.

6. 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.

7. The Oral Cavity

8. 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.

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

10. 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.

11. Papillae

12. Taste Regions

13. Tonsillitis

14. 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)

15. 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.

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

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

18. Esophagus • Muscular tube that connects your mouth to your stomach. • 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.

19. 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

20. Esophagus Stomach

21. The Stomach 3 parts: Fundus (upper portion) Body (middle section) Antrum (lower portion) FUNDUS ANTRUM BODY

22. 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.

23. 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.

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

25. Small Intestine

26. 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

27. 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.

28. Duodenum • 1 foot long • Receives food from the stomach • 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.

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

30. 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.

31. Large Intestine

32. Large Intestine • The appendix hangs from the large intestine. • The appendix has no clear function but can become inflamed and infected when clogged or blocked. • Thought to be involved with breakdown of plants during primitive life.

33. Large Intestine Sections

34. 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.

35. Gall Bladder • Storage tank for bile (a greenish-yellow liquid) that helps your body break down and use fats • Located under your liver and is shaped like a pear • After you eat the gallbladder contracts, forcing the bile into the cystic duct into the common bile duct.

36. Gall Bladder

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

38. Liver

39. The Liver • Produces BILE • 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.

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

41. Pancreas • Helps you digest food by breaking down carbohydrates, fats and proteins.

42. Recap..can you remember the food path?

43. Hernia • A hernia is the protrusion of an organ through a wall that normally contains it. • There are many different types of hernias and several involve organs in the digestive system. • An inguinal hernia for example is when part of the intestine protrude through the abdominal wall. It appears as a bulge in the skin and can be very painful.

44. Hernia • A hiatal hernia occurs when the upper part of the stomach protrudes upward through the diaphragm. This condition can lead to GERD (gastroesophageal reflux disease).

45. Heartburn • Has nothing to do with the heart - it is a digestive problem • Heartburn is a pain behind the breast bone, often described as ‘burning’ in quality. • Acid is present in the stomach to digest food. Heartburn occurs when small amounts of this acid rise up into the esophagus - the tube which carries food from the mouth to the stomach. This is called reflux. • The gullet, unlike the stomach, does not have a protective lining. So when it is exposed to the acid, it can become inflamed and painful.

46. Anorexia • Anorexia is an eating disorder classified as a refusal to maintain a minimally normal body weight. • Lack of appetite (-orexia = appetite) • A sign of malignancy or liver disease. • It is a loss of appetite caused by emotional problems such as anger, anxiety, and fear. • The individual is intensely afraid of gaining weight and has a disturbance in the perception of the shape or size of his/her body. • Predominantly affects adolescent females, and its principal symptom is a conscious, relentless attempt to diet along with excessive, compulsive over activity, such as exercise, running, or gymnastics. • Most postmenarchal females with this disorder are amenorrheic.

47. Bulimia • Bulimia Nervosa is an eating disorder that is characterized by binge eating (uncontrolled indulgence in food) followed by purging (eliminating food from the body). • Individuals maintain normal or nearly normal weight because after binging they engage in inappropriate purging. • E.g. self-induced vomiting and the misuse of laxatives or enemas.