1. ACTIVITY

2. Can you identify these organs?

3. Large Intestine

4. Oesophagus

5. Small Intestine

6. Stomach

7. Can you guess the length of the above organs?

8. Name of Organ
Length of Organ (cm)
Oesophagus
Stomach
Small Intestine
Large Intestine
Entire Digestive System

9. Name of Organ
Length of Organ (cm)
Oesophagus
~25
Stomach
~20
Small Intestine
~700
Large Intestine
~150
Entire Digestive System
~925

10. 5 Processes of Nutrition
Ingestion
Digestion
Absorption
Assimilation
Egestion

11. Ingestion
The taking-in of food

12. Digestion The breaking down of large molecules into smaller molecules
Rely on action of digestive enzymes

13. Absorption
The entrance of digested food molecules into blood streams by diffusion or active transport

14. Assimilation
The transportation of food particles to various parts of the body via blood streams

15. Egestion
The removal of undigested or unabsorbed food from the body in the form of faeces

16. Can you match each process to different parts of the alimentary canal?

17. Ingestion: mouth
Digestion: mouth, stomach and small intestine
Absorption: mainly in small intestine; some in stomach and large intestine
Assimilation: all over body
Egestion: anus

19. Ingestion

21. Types of Teeth

22. Incisors Located at front of jaws Sharp and chisel-like edge
For cutting food into pieces
Single root embedded in jaw bone

23. Canines Located next to the incisors Sharp and pointed
For piercing and tearing food
Single root embedded in jaw bone

24. Premolars Located on the sides of jaws Large with a flattened top
Cusps for crushing and grinding food

25. Molars Located at the back of the jaws, behind the premolars
Larger than the premolars
For crushing and grinding food

26. capillary nerve endings
enamel
crown
dentine
capillary nerve endings
gum
neck
pulp cavity
cement
root
periodontal membrane
jaw bone

27. External Structure of a Tooth
Crown – the part above the gum
Neck – the region between the root and the crown that is bounded by the gum
Root – the part embedded in the jaw bone

28. Internal Structure of a Tooth
1) Enamel
Outermost region
Hardest region of the tooth
97% of it is made of calcium and magnesium salts
Contains no living cells
Protects the tooth from mechanical damage

29. Internal Structure of a Tooth
2) Dentine (Ivory)
Middle region of a tooth
Bone-like substance
73% is inorganic matter (mainly calcium and phosphate crystals)
Make up the bulk of a tooth
Contains odontoblasts, the dentine-forming cells

30. Internal Structure of a Tooth
3) Pulp cavity
Innermost region of a tooth
Filled with living cells
Contains blood capillaries (to supply nutrients and oxygen to the dentine) and nerve endings (to produce sensations of pressure, pain and temperature)
Blood vessels and nerves enter the tooth through an aperture at the base of the root

31. Internal Structure of a Tooth
4) Cement
Thin layer of substance covering the dentine in the root
Similar to bone
Attached to a fibrous membrane called periodontal membrane – periodontal fibres connect the cement to the jaw bone
These fibres anchor the tooth firmly in place but still permit slight movement which helps to protect the tooth from mechanical damage

33. What is the difference between their teeth?
I have milk teeth
We have permanent teeth

34. Milk Teeth vs. Permanent Teeth
Milk teeth start to develop after birth
Begin to show when child is about 5 months old
Begin to shed when child is between 7 and 11 years old
Permanent teeth are fully developed by age 17
Permanent teeth stop growing once they are fully developed, and cannot be replaced if damaged

35. Dentition and Dental Formula
Dentition – represents the number and arrangement of different types of teeth
Dental formula – a formula that shows the number of different types of teeth on the upper and the lower jaws
i = incisors c = canines
pm = premolars m = molars

36. Dental Formula of Humans
Milk Dentition
Permanent Dentition
Dental Formula
i 2, c 1, m 2
(or 212)
212
i 2, c 1, pm 2, m 3
(or 2123)
2123
Total Number of Teeth
( ) x 2 x 2
= 20
( ) x 2 x 2
= 32

37. Which of the following is a Human skull?

39. Skull of Human (Omnivore)

40. Skull of Herbivore

41. Dentition of Herbivores
Herbivores – feed on plants only
Their dentition is adapted for cutting and grinding grasses and plant tissues
Diastema – a space in front of the premolars to allow grass to be moved freely inside the mouth

42. Skull of Carnivore

43. Dentition of Carnivores
Carnivores – feed on animals only
Their dentition is adapted for killing preys and eating animal tissues (e.g. gripping, cutting and tearing flesh, etc.)
Carnassial teeth – the last upper premolar and the first lower molar on each side of the jaws. Can cut through flesh and crush bones when the jaws move up and down