1. Digestive System

2. A. Functions
a. Break food down into usable nutrients

3. Functions
b. Absorb nutrients into the bloodstream

4. Functions
c. Rid body of indigestible remains

5. Accessory Digestive Organs
Two Main Groups:
Alimentary
Canal
Accessory Digestive Organs

6. B. Alimentary Canal
(gastrointestinal tract) continuous tube from mouth to anus

7. Alimentary Canal
a. About 9 meters long in cadavers

8. Alimentary Canal b. Job – breaks down food and absorbs nutrients
c. Organs – mouth, pharynx, esophagus, stomach, small intestine, and large intestine

9. C. Accessory Digestive Organs
a. Job – aid in the breakdown and absorption of nutrients
b. Organs – teeth, tongue, gallbladder, salivary glands, liver, and pancreas

10. Digestive Processes Ingestion Propulsion Mechanical Digestion
Chemical Digestion
Absorption
Defecation

11. Ingestion
A. Taking food into the body

12. Propulsion B. Moving food through the GI tract
a. Swallowing – voluntary
b. Peristalsis - involuntary

13. Peristalsis
Wave-like muscle contractions that move food through the GI tract
So powerful it defies gravity

14. C. Mechanical Digestion
Breaks food into smaller pieces
a. Chewing – mouth
b. Churning – stomach
c. Segmentation – small intestine

15. Segmentation
Squeezing and mixing food with digestive juices in segments

16. D. Chemical Digestion
Enzymes break food down into smaller, simpler molecules

17. E. Absorption
Movement of vitamins, minerals, water from GI tract to blood
Mostly happens in small intestines

18. F. Defecation Eliminating indigestible substances from the body
a. Feces – solid waste matter

19. Organs of the Digestive System

20. A. Mouth – oral cavity, where ingestion occurs

21. Mouth
a. Lips and Cheeks – keep food inside the mouth while chewing

22. Mouth
b. Palate – roof of the mouth

23. Hard palate
rigid surface helps with food breakdown during chewing

24. Soft palate
initiates swallowing, contains uvula

25. Uvula
Closes nasal passage when swallowing to keep food out

26. Uvula

27. B. Teeth
a. 32 permanent b. 20 deciduous (baby teeth)

28. Teeth
c. Incisors – 8, for biting, cutting, shearing

29. Teeth
d. Canines – (cuspids) 4, for stabbing and tearing

30. Teeth
e. Premolars – (bicuspids) 8, for crushing

31. Teeth
f. Molars – 12, for crushing and grinding

32. Wisdom Teeth – 3rd molars

33. Wisdom Teeth Extraction

34. Teeth

35. Gingiva
g. Gums that surround base of teeth

36. Problems
Gingivitis
Periodontal Disease

37. So take good care of them…

38. C. Tongue
Forms base of mouth, highly muscular

39. a. Jobs of Tongue
Mixes food with saliva
Speech
Taste
Swallowing

40. Bolus
b. Ball of food that is ready to be swallowed

41. Frenulum
c. Membrane that attaches tongue to floor of mouth

42. Tongue-tied

43. Papillae
d. Peg-like projections that cover the tongue surface

44. Taste buds
e. Found in grooves, detect taste

45. Tastes – Sweet, Salty, Sour, Bitter, Umami (steak and cheese)

46. D. Salivary Glands
Produce saliva to begin chemical digestion

47. 3 pairs Parotid – large, in front of ear Submandibular – along the jaw
Sublingual – below the tongue

48. Saliva
b. Made of water, digestive enzymes, mucus, and antibacterial agents

49. Mouths are covered in bacteria

50. E. Pharynx - back of the throat
a. Connects oral cavity to esophagus
Both Respiratory and Digestive Systems

51. What can you see?

52. F. Esophagus
Long muscular tube that carries food to the stomach

53. Esophagus
a. About 10 inches long b. Longitudinal folds collapse when empty

54. Esophagus

55. Esophagus

56. Esophagus

57. Diaphragm
c. Esophagus passes through hole in diaphragm to reach the stomach

58. Lower Esophageal Sphincter
d. Acts as a valve to keep food and juices in the stomach

59. Heartburn
LES is relaxed and allows stomach acids back up into the esophagus

60. Other Damage
Barretts, Acid reflux, Ulcers, Cancer