1. The Digestive System

2. Introduction
The digestive system is used for breaking down food into nutrients which then pass into the circulatory system and are taken to where they are needed in the body.

3. Components Esophagus Stomach Small Intestine Large Intestine
Gall bladder
Liver
Pancreas

4. There are four stages to food processing:
Ingestion: taking in food
Digestion: breaking down food into nutrients
Absorption: taking in nutrients by cells
Egestion: removing any leftover wastes

5. I. The Digestive Process Begins
       
1. Digestion:
The process by which
your body breaks down
food into small nutrient
molecules.
(mechanical and chemical)

6. 2. Absorption: The process by which nutrient molecules
pass through the wall of your digestive
system into your blood.

7. 3. Elimination:
Materials that are not absorbed are eliminated from the body as waste (ie. Fiber)

8. Diagram of Digestive System

9. Mouth Chemical and mechanical digestion.
Food is chewed (masticated) mechanically.
A bolus (lump) is formed with saliva and the tongue.

10. B. Mouth
Saliva: Fluid released when your mouth waters and plays an important part in both mechanical and chemical digestion.
Types of Digestion
Mechanical Digestion- Teeth begin digestion by cutting, tearing, and grinding food

11. mouth
break up food
digest starch
kill germs
moisten food

12. C. Esophagus- Total Time 10 seconds.
1.           1. Epiglottis:
Flap of tissue that seals off your windpipe preventing food from entering.
2. Esophagus:
Food enters a muscular tube that connects the mouth to the stomach.
3. Mucus:
Thick, slippery substance that lines the esophagus in order to make food easier to swallow and move along

13. You have a trap door called the epiglottis to cover your windpipe when you swallow.

14. Peristalsis
series of involuntary wave-like muscle contractions which move food along the digestive tract

15. Stomach Food is temporarily stored here. Gastric juices are secreted.
Has layers of muscle that line the inside.
Mechanically and chemically breaks down food.

16. Mechanical Digestion: Three strong layers of smooth muscle contract to produce a churning motion. (similar to a washing machine)
2. Chemical Digestion: Churning food makes contact with digestive juices.
a. Enzyme Pepsin- Works best in an acid environment.
    b. Hydrochloric Acid (HCl).-Kills many bacteria that you swallow with food, mucus protects stomach lining from this acid.
c. Food remains in the stomach until the entire solid has been broken down.

17. Your stomach mashes your food the way a baker kneads dough for bread.

19. Your stomach stretches when you eat like a balloon being filled with air

20. mouth
break up food
digest starch
kill germs
moisten food
stomach
kills germs
break up food
digest proteins
store food
sphincter
sphincter

21. Small Intestine Most chemical digestion takes place here.
Simple sugars and proteins are absorbed into the inner lining.
Fatty acids and glycerol go to lymphatic system.
Lined with villi, which increase surface area for absorption, one cell thick.

22. 3. Absorption in the Small Intestine
Villi:
Fingerlike structures increase the surface area of the small intestines and allow nutrient molecules to pass into the blood

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

24. Large Intestine Solid materials pass through the large intestine.
These are undigestible solids (fibers).
Water is absorbed.
Vitamins K and B are reabsorbed with the water.
Rectum- solid wastes exit the body.

25. Large intestines (colon)
Function
re-absorb water
use ~9 liters of water every day in digestive juices
> 90% of water reabsorbed
not enough water absorbed
diarrhea
too much water absorbed
constipation

26. B. The Large Intestine
-The last section of the digestive system that contain bacteria that feed on material and make vitamins (1.5 meters long)
-The role is absorb water into the bloodstream and get remaining material ready for elimination.

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

28. Rectum Last section of colon (large intestines) eliminate feces
undigested materials
extracellular waste
mainly cellulose from plants
roughage or fiber
masses of bacteria

29. Accessory Organs
Pancreas
Gall Bladder
Spleen

30. Pancreas
An organ which secretes both digestive enzymes (exocrine) and hormones (endocrine)
** Pancreatic juice digests all major nutrient types.
Nearly all digestion occurs in the small intestine & all digestion is completed in the SI.

31. Gall bladder
Pouch structure located near the liver which concentrates and stores bile
Bile duct – a long tube that carries BILE. The top half of the common bile duct is associated with the liver, while the bottom half of the common bile duct is associated with the pancreas, through which it passes on its way to the intestine.

32. BILE Bile emulsifies lipids (physically breaks apart FATS)
Bile is a bitter, greenish-yellow alkaline fluid, stored in the gallbladder between meals and upon eating is discharged into the duodenum where it aids the process of digestion.

33. mouth
break up food
digest starch
kill germs
moisten food
stomach
kills germs
break up food
digest proteins
store food
liver
produces bile
- stored in gall bladder
break up fats
pancreas
produces enzymes to
digest proteins & starch

34. Healthy Habits
Eat foods that are high in fiber like fruits and vegetables

35. Drink plenty of water

36. Chew your food completely before you swallow

37. Avoid foods high in fat

38. Interesting Facts
Food is in your digestive system for about 24 hours