1. Digestion - a process of breaking down large food molecules into smaller molecules.
2. Human digestive system are alimentary canal (mouth, oesophagus, stomach, small intestine, large intestine, rectum and anus), liver and pancreas.
3. Flow of food:
4.Process of digestion:
a) Mouth - Physical digestion by teeth ( grinding, chewing)
- Chemical digestion by saliva which contain amylase will digest starch to maltose.
b) Oesophagus - pass food form mouth to stomach by peristalsis.
c) Stomach - produce gastric juice which contain Hydrochloric acid, protease and casein
i) Hydrochloric acid - stops the action of amylase, kills bacteria and provides acidic medium
ii) Protease - break down proteins into polypeptides
iii) Casein - coagulate liquid milk into solid form
d) Duodenum - the first part off small intestine. It is joined to the liver and pancreas
i) Liver - produce bile to emulsify fats and oil into small droplets.
ii) Gall bladder - stored bile
iii) Pancreas - produce pancreatic juice which contains:
Amylase: breakdown starch into maltose
Protease: breaks down proteins into polypeptides
Lipase: break down fats into fatty acids and glycerol
e) Ileum - lower part of small intestine which produce intestinal juice that contains:
Maltase: break down maltose into glucose
Protease: break down polypeptides into amino acid
Lipase: break down fat into fatty acid and glycerol
f) Large intestine - reabsorption of water
g) Rectum - stored faeces
h) Anus - removed faeces
5. End products of digestion:
Carbohydrates -----> Glucose
Proteins ---------> Amino acid
Fats --------> Fatty acid and glycerol