This upload is on the Digestive system.

1. Digestion
Done by: Ooi huiying

2. Digestion
 The process whereby large food
molecules are broken down into smaller,
soluble, diffusible, simpler forms that can
be absorbed into our body.
 Physical-Mechanical breakdown of food
into smaller particle
 Chemical- Enzymatic hydrolysis of food
substances

3. Mouth & Buccal Cavity
Mouth
The opening that food enters & leads to the
buccal cavity.
Buccal Cavity
Tongue- Mixes food with saliva (Amylase)
- Rolls food into Bolus
- Pushes food down the Pharynx
Teeth- Chews food into smaller pieces for
enzymatic reactions. (mastication)

4. Oesophagus ( gullet)
 Consist of the inner circular muscles and outer
longitudinal muscles.
 Does not digest food.
 It is a muscular tube that pushes food down
the body through peristalsis.
 Peristalsis is the strong and rhythmic
movement.
 The inner circular muscles relaxes and the outer longitudinal muscles contracts, the
lumen widens for food to enter.
 When the inner circular muscles contracts and the outer longitudinal muscles relaxes,
the food is pushed forward.

5. Stomach
 A distensible, muscular bag with thick and well-
developed muscular walls.
 It creates powerful muscular contractions called
churning, which mixes food with gastric juices to
form chyme.
 Gastric juice : Hydrochloric acid
Protease(Digest proteins)
 Acidic environment: To kill germs & pasticides.
Provide an optimum environment for protein
digestion (Ph 1-2.5). Stop action of salivary
amylase

6. Small intestine
 6m long connected with liver and pancreas.
 Consists of : U-shaped duodenum
Jejunum
ileum
 Bile
 Pancreatic juice : Pancreatic amylase,
Pancreatic lipase, protease
 Intestinal juice: Peptidase,maltase,lipase
 Mucus is produced.

7. Villus
 Finger-like
structures which increases
surface area for digestion

8. Liver
 Produces a yellowish-green fluid called
bile.
 Bile does not contain enzymes but helps in
fat digestions through the process of
emulsification.
 Emulsification is the breaking down of fats
molecules into smaller droplets to increase
surface area for fat digestion.
 Bile is temporarily stored in gall bladder.

9. Pancreas
 Situated between stomach and small
intestine.
 Secretes pancreatic juice (alkaline)
containing amylase, protease.
 Alkaline juice neutralizes the acid in the
food from stomach.

10. Large intestine
 About 1.5 m long
 Absorbs remaining water and minerals
salts.

11. Rectum
 Near
solid waste called Faeces is
temporarily stored in the rectum.

12. Anus
 Faeces is forced out of the gut through
anus. (Egestion)
 Faeces contains mainly digested food
and unabsorbed material.
 Faeces contains dead bacterial,
cellulose, mucus, cholestrol,water.

13. Enzymes & their reactants
Enzymes reaction
Protease Proteins- Amino acids
Lipase Fats- glycerol + fatty acids
Amylase Starch- maltose
Maltase Maltose- glucose

14. Enzymes.
 Pancreatic juice : Amylase, maltose
protease, lipase.
 Intestinal juice : Maltose, protease, lipase