1. Digestive System

2. Digestive System Mechanical digestion Food chewed and mixed in mouth.
I. Digestion – the process that breaks food into small molecules so they can be absorbed or taken into body cells.
Mechanical digestion
Food chewed and mixed in mouth.
Food churned in stomach.
Food acted on by bile.

3. Digestive System B. Chemical digestions
Breaks down large molecules to smaller.
In mouth , stomach, small
intestines
3. Enzymes
Proteins vital for chemical digestion
Enters a reaction and helps to join or break up into substances
Are not changed themselves
Can speed up reactions

4. Digestive System Mechanical digestion by tongue and teeth
II. Digestion in mouth
Diagram of the mouth
Mechanical digestion by tongue and teeth
Chemical digestion
Saliva
Produced by the 3 sets of salivary glands
Mostly water, but also contains mucus and enzymes (amylase)
Amylase starts breakdown of starch to sugar.

5. Digestive System Muscular tube 25 cm. long No digestion
C. Esophagus
Esophagus Diagram
Muscular tube
25 cm. long
No digestion
Peristalsis- waves of contractions that move food
Takes about 4 to 8 seconds
Peristalsis found throughout digestive systems

6. Digestive System A muscular bag with folds on the inside
III. Digestion in the Stomach
Diagram of the stomach
A muscular bag with folds on the inside
Mechanical digestion done by walls of stomach and peristalsis.
Real view

7. Digestive System C. Chemical digestion Inside the stomach
Hydrochloric acid
Enzymes work on protein
Mucus
Lubricates food, making it slick
Protects stomach lining from strong digestive juices
D. Food in stomach about 4 hours
E. Food changed to chyme - thin , watery liquid

8. Digestive System Small in diameter, but about 6-7 M long
IV. Digestion in the small intestine
Small intestines Diagram
Small in diameter, but about 6-7 M long
- first part of the duodenum small intestine
Major part of all digestion
Receive digestive juices from outside the digestive tract
Bile
From the liver
Greenish color

9. Digestive System Diagram of gallbladder
Small intestines continue
Diagram of gallbladder
3. Store in small sac : the gall bladder
4. Breaks fat molecules into smaller pieces
(like detergent acts on grease)
b. Pancreas
Produces insulin - helps body use sugar and other carbohydrates
Produces enzymes that break down carbohydrates, fats, proteins still further

10. Digestive System Many ridges and folds Folds covered with villi
C. Walls of small intestine
Many ridges and folds
Folds covered with villi
Tiny, finger like projections
Make surface area larger so there are more places for to be absorbed.

11. Digestive System
D. Chyme is now a soup of Molecules ready to be absorbed through cells on surface of villi.
Capillaries around the villus
Molecules of nutrients pass by diffusion and osmosis or by active transport into blood vessels of each villus.
Remaining materials are moved into large intestines by peristalsis.

12. Small Intestine

13. Digestive System Main job: absorb water from the thin mixture (chyme)
V. Absorption in large intestine
Large intestines
Main job: absorb water from the thin mixture (chyme)
Homeostasis is maintained.
Peristalsis slows down some.
Chyme may stay in large intestine for 3 days
Water and sodium are absorbed.

14. Digestive System Undigested cellulose Bacteria
D. Remaining materials
Undigested cellulose
Bacteria
Feed on undigested matter
Produce vitamins.
This is an example of a symbiotic relationship.

15. Digestive System Controlled by muscles in the rectum and anus.
E. Release of solidified wastes
Controlled by muscles in the rectum and anus.
Release in the form of feces.

16. Digestive System
Remember
Colon:
Food is processed in your digestive system for the purpose of supplying your body with raw materials for metabolism. These raw materials are in the form of nutrients.