1. Digestive System

2. Salivary Glands
Mouth
Esophogus
Liver
Stomach
Pancreas
Large intestine
Small intestine
Rectum
Anus

3. Digestion: Accessory Organs –food does not enter these organs
Liver – produces bile, aids in digestion of fats
Gall Bladder – stores bile
Pancreas – produces pancreatic juices and insulin

4. Chemical Environment of the GI Tract
Neutral in mouth
(pH approx 7)
Acid in stomach
(pH approx 2)
Neutral in small intestine
- (pH approx 7)

5. Digestion The process of PHYSICALLY and
CHEMICALLY……Changing food and nutrients in the digestive tract into particles usable by cells.

6. Digestion: Physical Changes
Grinding and mixing by teeth (MASTICATION) in the mouth and muscular actions of the stomach and small intestine
Liquefying by the addition of water and digestive juices in the mouth, stomach and small intestine (GASTROINTESTINAL TRACT/ GI TRACT)

7. Digestion: Chemical Changes
Complex nutrients are broken down into particles using chemical reactions:
Starch and disaccharides to monosaccharides
Proteins to amino acids
Fats to fatty acids to glycerol

8. Enzymes Big food molecules can’t pass through cell walls
ENZYMES are used to break up big molecules into small ones (they act like chemical scissors).
These small molecules can pass through the wall of the small intestine into the blood then into cells
Chemical changes occur because of digestive enzymes

9. Big food molecules can’t pass through cell walls.
ENZYMES are used to break up big molecules into small ones (they act like scissors).
These small molecules can pass through the wall of the small intestine into the blood then into cells

10. Digestion: Mouth Physical Changes: -Teeth grind food
-Salivary glands add water
Chemical Changes:
-Salivary amylase
-breaks down starches
into sugars

11. Digestion: Esophagus Transport tube
Peristalsis: muscular contractions move the bolus (food) to stomach
Enables swallowing to move bolus (food) from the mouth to the stomach
No enzymes added

12. Digestion: Stomach pH rapidly decreases
Inflow of gastric juice containing HCL (hydrochloric acid)
pH rapidly decreases
Mucus (thick fluid) helps soften and lubricate food
Protein digestion starts with the enzyme pepsin starting this
The mixture of food and juices is called chyme

13. Digestion: Release from stomach to small intestine (SI)
Chyme released in small bolus to small intestine
gall bladder releases bile which is produced by liver and aids in digestion of fats = physical (mechanical) digestion
pancreatic juices released continue to digest proteins and carbs = chemical digestion

14. Digestion: Large Intestine
Water is absorbed with the aid of bacteria which also help make vitamins
NO DIGESTION takes place
Undigested food is solid waste call feces

15. Rectum
Compacts and stores solid waste

16. Anus Opening through which “feces” = solid waste leaves the body
Voluntary Action

17. Match the organ to its function!!
Mouth
1. This is where water is absorbed.
Gullet
2. Makes bile which breaks up fats and it is alkaline to give the right pH for the enzymes in the S. intestine.
Stomach
3. Makes all 3 enzymes.
Liver
4. Mixes the food with enzymes that digest proteins AND contains acid to kill bacteria.
Pancreas
5. Produces more enzymes AND this is where the food is absorbed through the gut wall into the blood.
Small intestine
6. Chew and mix the food with saliva (contains enzymes).
Large intestine
7. Links the mouth to the stomach.
Rectum
8. Here food that can’t be digested is stored as faeces and then leaves through the anus.

18. The End