1. The Digestive System

3. Mechanical digestion is the first step of the digestion process and begins immediately after ingestion.

4. Mechanical digestion is the actual process of mastication (chewing) of food by teeth, to break the ingested food into smaller pieces that are more readily digested through chemical digestion. This mastication is mixed with saliva, which contains some enzymes to begin the chemical digestion process. Mechanical digestion also involves the process known as peristalsis. Peristalsis is accomplished by smooth muscle within the body and is responsible for the movement of food through the intestinal tracts.

5. Mechanical digestion is the actual process of mastication (chewing) of food by teeth, to break the ingested food into smaller pieces that are more readily digested through chemical digestion.

6. This mastication is mixed with saliva, which contains some enzymes to begin the chemical digestion process. Mechanical digestion also involves the process known as peristalsis.

8. Chemical digestion is accomplished through the use of chemicals known as digestive enzymes. These enzymes and water are responsible for the breakdown of complex molecules.

9. These complex molecules, such as fats, proteins, and carbohydrates, are digested (broken down) into smaller molecules.

12. Esophagus

13. Stomach

14. Small Intestine

15. Pancreas

16. Liver

17. Gall Bladder

18. Large Intestine

19. Rectum

23. The stomach’s main function: storing the food we eat, breaking down the food into a liquidly mixture called chyme, mixing enzymes which is are chemicals that break down food, and slowly empties that liquidly mixture into the small intestine.

24. The stomach is a hollow organ, or "container," that holds food while it is being mixed with enzymes that continue the process of breaking down food into a usable form.

26. By the time ingested food reaches the small intestine, it has been mechanically broken down into a liquid. As this liquid flows across the inner surface of the small intestine (which has many small folds to increase the surface area), nutrients within the food come into contact with the many small blood vessels which surround the small intestine.

27. The large intestine is the thick, lower end of the digestive system, containing the appendix, colon and rectum.

29. These enzymes break down protein, fats, and carbohydrates.

30. The pancreas also makes insulin, secreting it directly into the bloodstream. Insulin is the chief hormone for metabolizing sugar.

31. The main function of the liver is to process the nutrients absorbed from the small intestine.

32. Bile from the liver secreted into the small intestine also plays an important role in digesting fat.

33. The liver is the body’s chemical "factory." It takes the raw materials absorbed by the intestine and makes all the various chemicals the body needs to function.

35. The ingestion of food and especially fats cause the release of a hormone, cholecystokinin, (CCK) which in turn signals the relaxation of the valve at the end of the common bile duct (the sphincter of oddi) which lets the bile enter the small intestine.

38. It is the rectum's job to receive stool from the colon, to let the person know that there is stool to be evacuated, and to hold the stool until evacuation happens.

39. When anything (gas or stool) comes into the rectum, sensors send a message to the brain. The brain then decides if the rectal contents can be released or not. I

40. f they can, the sphincters relax and the rectum contracts, disposing its contents.

41. If the contents cannot be disposed, the sphincter contracts and the rectum accommodates so that the sensation temporarily goes away.

42. The anus is the last part of the digestive tract. It is a 2-inch long canal consisting of the pelvic floor muscles and the two anal sphincters (internal and external).

43. The anus is surrounded by sphincter muscles that are important in allowing control of stool.

44. The pelvic floor muscle creates an angle between the rectum and the anus that stops stool from coming out when it is not supposed to.

45. The internal sphincter is always tight, except when stool enters the rectum. It keeps us continent when we are asleep or otherwise unaware of the presence of stool.