ACTIVITYACTIVITY

Can you identify these Can you identify these organs?organs?

Large IntestineLarge Intestine

OesophagusOesophagus

Small IntestineSmall Intestine

StomachStomach

Can you guess the Can you guess the length of the above length of the above

organs?organs?

Name of OrganName of Organ Length of Organ Length of Organ (cm)(cm)

OesophagusOesophagus

StomachStomach

Small IntestineSmall Intestine

Large IntestineLarge Intestine

Entire Digestive Entire Digestive SystemSystem

Name of OrganName of Organ Length of Organ Length of Organ (cm)(cm)

OesophagusOesophagus ~25~25

StomachStomach ~20~20

Small IntestineSmall Intestine ~700~700

Large IntestineLarge Intestine ~150~150

Entire Digestive Entire Digestive SystemSystem

~925~925

5 Processes of Nutrition5 Processes of Nutrition

1)1) IngestionIngestion

2)2) DigestionDigestion

3)3) AbsorptionAbsorption

4)4) AssimilationAssimilation

5)5) EgestionEgestion

IngestionIngestion

• The taking-in of foodThe taking-in of food

DigestionDigestion

• The breaking down of large The breaking down of large molecules into smaller molecules molecules into smaller molecules

• Rely on action of digestive Rely on action of digestive enzymesenzymes

AbsorptionAbsorption

• The entrance of digested food The entrance of digested food molecules into blood streams by molecules into blood streams by diffusion or active transportdiffusion or active transport

AssimilationAssimilation

• The transportation of food The transportation of food particles to various parts of the particles to various parts of the body via blood streamsbody via blood streams

EgestionEgestion

• The removal of undigested or The removal of undigested or unabsorbed food from the body unabsorbed food from the body in the form of faecesin the form of faeces

Can you match each Can you match each process to different process to different

parts of the alimentary parts of the alimentary canal?canal?

• IngestionIngestion: mouth: mouth• DigestionDigestion: mouth, : mouth,

stomach and stomach and small intestinesmall intestine

• AbsorptionAbsorption: : mainly in small mainly in small intestine; some in intestine; some in stomach and stomach and large intestinelarge intestine

• AssimilationAssimilation: all : all over bodyover body

• EgestionEgestion: anus: anus

IngestionIngestion

Types of TeethTypes of Teeth

IncisorsIncisors

• Located at front of jawsLocated at front of jaws• Sharp and chisel-like edgeSharp and chisel-like edge• For cutting food into piecesFor cutting food into pieces• Single root embedded in jaw boneSingle root embedded in jaw bone

CaninesCanines

• Located next to the incisorsLocated next to the incisors• Sharp and pointed Sharp and pointed • For piercing and tearing foodFor piercing and tearing food• Single root embedded in jaw boneSingle root embedded in jaw bone

PremolarsPremolars

• Located on the sides of jawsLocated on the sides of jaws• Large with a flattened top Large with a flattened top • Cusps for crushing and Cusps for crushing and

grinding food grinding food

MolarsMolars

• Located at the back of the jaws, Located at the back of the jaws, behind the premolars behind the premolars

• Larger than the premolars Larger than the premolars • For crushing and grinding foodFor crushing and grinding food

root

enamel

dentine

gum

pulp cavity

jaw bone

cement

periodontal membrane

crown

neckcapillary

nerve endings

External Structure of a External Structure of a ToothTooth

1)1) Crown – the part above the gumCrown – the part above the gum

2)2) Neck – the region between the Neck – the region between the root and the crown that is root and the crown that is bounded by the gumbounded by the gum

3)3) Root – the part embedded in Root – the part embedded in the jaw bonethe jaw bone

Internal Structure of a Internal Structure of a ToothTooth

1) Enamel1) Enamel- Outermost regionOutermost region- Hardest region of the toothHardest region of the tooth- 97% of it is made of calcium and 97% of it is made of calcium and

magnesium saltsmagnesium salts- Contains no living cellsContains no living cells- Protects the tooth from mechanical Protects the tooth from mechanical

damagedamage

Internal Structure of a Internal Structure of a ToothTooth

2) Dentine (Ivory)2) Dentine (Ivory)- Middle region of a toothMiddle region of a tooth- Bone-like substanceBone-like substance- 73% is inorganic matter (mainly 73% is inorganic matter (mainly

calcium and phosphate crystals)calcium and phosphate crystals)- Make up the bulk of a toothMake up the bulk of a tooth- Contains odontoblasts, the dentine-Contains odontoblasts, the dentine-

forming cellsforming cells

Internal Structure of a Internal Structure of a ToothTooth

3) Pulp cavity3) Pulp cavity- Innermost region of a toothInnermost region of a tooth- Filled with living cellsFilled with living cells- Contains blood capillaries (to supply Contains blood capillaries (to supply

nutrients and oxygen to the dentine) and nutrients and oxygen to the dentine) and nerve endings (to produce sensations of nerve endings (to produce sensations of pressure, pain and temperature)pressure, pain and temperature)

- Blood vessels and nerves enter the tooth Blood vessels and nerves enter the tooth through an aperture at the base of the through an aperture at the base of the rootroot

Internal Structure of a Internal Structure of a ToothTooth

4) Cement4) Cement- Thin layer of substance covering the Thin layer of substance covering the

dentine in the rootdentine in the root- Similar to boneSimilar to bone- Attached to a fibrous membrane called Attached to a fibrous membrane called

periodontal membrane – periodontal periodontal membrane – periodontal fibres connect the cement to the jaw fibres connect the cement to the jaw bonebone

- These fibres anchor the tooth firmly in These fibres anchor the tooth firmly in place but still permit slight movement place but still permit slight movement which helps to protect the tooth from which helps to protect the tooth from mechanical damagemechanical damage

What is the difference between What is the difference between their teeth?their teeth?

I have I have milk milk teethteeth

We have We have permanepermanent teethnt teeth

Milk Teeth vs. Permanent Milk Teeth vs. Permanent TeethTeeth

• Milk teeth start to develop after birthMilk teeth start to develop after birth• Begin to show when child is about 5 months Begin to show when child is about 5 months

old old • Begin to shed when child is between 7 and 11 Begin to shed when child is between 7 and 11

years oldyears old• Permanent teeth are fully developed by age Permanent teeth are fully developed by age

1717• Permanent teeth stop growing once they are Permanent teeth stop growing once they are

fully developed, and cannot be replaced if fully developed, and cannot be replaced if damageddamaged

Dentition and Dental Dentition and Dental FormulaFormula

• Dentition – represents the number and Dentition – represents the number and arrangement of different types of arrangement of different types of teethteeth

• Dental formula – a formula that shows Dental formula – a formula that shows the number of different types of teeth the number of different types of teeth on the upper and the lower jawson the upper and the lower jaws

• i = incisorsi = incisors c = caninesc = canines

pm = premolarspm = premolars m = molarsm = molars

Milk Milk DentitionDentition

Permanent Permanent DentitionDentition

Dental Dental FormulaFormula

i i 22, c , c 11, m , m 22 2 1 22 1 2(or (or 212212)) 212212

i i 22, c , c 11, pm , pm 22, , m m 33 2 1 2 2 1 2 3 3(or (or 21232123)) 21232123

Total Total Number of Number of TeethTeeth

(2 + 1 + 2) x 2 (2 + 1 + 2) x 2 x 2 x 2

= 20= 20

(2 + 1 + 2 + 3) (2 + 1 + 2 + 3) x 2 x 2 x 2 x 2

= 32= 32

Dental Formula of Dental Formula of HumansHumans

Which of the Which of the following is a following is a Human skull?Human skull?

Skull of Human Skull of Human (Omnivore)(Omnivore)

Skull of HerbivoreSkull of Herbivore

Dentition of HerbivoresDentition of Herbivores

• Herbivores – feed on plants onlyHerbivores – feed on plants only• Their dentition is adapted for cutting Their dentition is adapted for cutting

and grinding grasses and plant and grinding grasses and plant tissuestissues

• DiastemaDiastema – a space in front of the – a space in front of the premolars to allow grass to be premolars to allow grass to be moved freely inside the mouthmoved freely inside the mouth

Skull of CarnivoreSkull of Carnivore

Dentition of CarnivoresDentition of Carnivores

• Carnivores – feed on animals onlyCarnivores – feed on animals only• Their dentition is adapted for killing Their dentition is adapted for killing

preys and eating animal tissues (e.g. preys and eating animal tissues (e.g. gripping, cutting and tearing flesh, etc.)gripping, cutting and tearing flesh, etc.)

• Carnassial teethCarnassial teeth – the last upper – the last upper premolar and the first lower molar on premolar and the first lower molar on each side of the jaws. Can cut through each side of the jaws. Can cut through flesh and crush bones when the jaws flesh and crush bones when the jaws move up and downmove up and down