1. Animal
Digestive
System

2. 3 main groups
• Herbivore
–Plants only
• Carnivore
–Meat only
• Omnivore
–Both plants and meat

3. The Digestive System

4. Mechanical breakdown of food
1. Teeth
2. Contractions in stomach wall
3. Peristalsis
Rhythmic muscular contraction
and relaxation in the wall of the
alimentary canal causing the food
to move along the canal

5. Animal Teeth
Incisors Cutting
Canines Tearing
Pre molars
Crushing
and
grinding
Molars

6. Oesophagus
A muscular tube
Connects Pharynx
to stomach
Food moves down
the Oesophagus by
Peristalsis

7. Stomach
J shaped muscular bag
Stores food for about 4 hours
Churns and mixes food
with gastric juice
forming Chyme
Digest food

8. Digestion in the Stomach
1. Mechanical Digestion
Peristalsis physically breaks up food particles
2. Chemical Digestion
using Gastric Juice containing
a. Mucus
b. HCl
c. Pepsinogen

9. Small Intestine
Muscular tube
Functions
Digestion
Absorption
Has three parts
1. duodenum
2. jejunum
3. ileum

10. Villi
Infolding in the lining of the small intestine
Function
Increase
surface area
for absorption
of digested
food

11. Large Intestine
Colon
Caecum
Appendix
Rectum Anus

12. Large Intestine Functions (Colon)
1. Reabsorb water
2. Produce B group vitamins
3. Digest cellulose

13. Large Intestine
Functions
Caecum
Appendix
Function unknown
in humans
Rectum
Stores Faeces

14. Role of the Liver
in digestion
The liver produces bile
Bile is a yellow-green liquid
Bile is stored in the gall
bladder
Bile enters the
duodenum through the

15. Bile consists of
1. Water 2. Bile salts 3. Bile pigments
Function of bile
1. Emulsifies fat This increases the surface
area of the fat droplets
2. Neutralises the acidic chyme from stomach

17. • At the mouth the large food molecules are taken
into the gut - this is called ingestion.
• They must then be broken down into smaller
ones by digestive enzymes – digestion.
• they can then be taken from the gut into the
blood stream - absorption.
• The cells of the body can then use these small
molecules - assimilation.
• The indigestible waste products are eliminated
from the body by the act of egestion.

18. Three enzymes involved in digestion
Enzymes are biological catalysts
1 Amylase
2 Pepsin
3 Lipase

19. Common Ailments of the Digestive
system
• Constipation
– Failure to pass faeces
– Caused by dehydration, poor fibre in diet
– Improve fibre in diet to treat
• Diarrhoea
– Passing abnormal amount of faeces (usually watery)
– Caused by infection, stress, colitis
– Withhold food and treat with medicine
• Pancreatitis
– Inflammation of the pancreas
– Caused by viral infection
– Withhold food for 72h and introduce low-fat diet, fluid therapy
and antibiotics

20. End