1. Digestive enzymes Recap Starch Proteins Lipids/ Fats maltose
AMYLASE
Starch
maltose
PROTEASE
Proteins
amino acids
LIPASE
Lipids/ Fats
fatty acids &
glycerol

2. identify and describe the main regions of alimentary canal
describe the functions of the parts of the human gut and the associated organs

3. Pathway of Digestion in Alimentary Canal
Mouth ↓
Oesophagus
Stomach
Small Intestines
Large Intestines
Rectum
Anus

4. Digestion is the process of breaking down complex, large molecules (food) into simple, soluble and diffusible molecules so that it can be absorbed by the body and be used to build and nourish cells and to provide energy.

5. Functions of digestive system:
(1) Ingestion: taking food into the body.
(2) Digestion: breakdown of food materials into smaller amounts        (i) Mechanical digestion       (ii) Chemical digestion
(3) Absorption
(4) Assimilation
(5) Egestion

6. Types of digestion: (i) Mechanical digestion
Break down particles into smaller pieces so as to increase the surface area for the action of enzymes.
(ii) Chemical digestion
Involves enzymatic reactions which digest the food into simpler chemical forms.
Hydrolysis splits the large molecules by addition of water.

7. How is Food Digested? Mouth
Ingestion is the process of taking food into the body.
The tongue rolls and lubricates food with mucus and saliva.
Chemical digestion of starch starts here by salivary amylase.
Oesophagus
It takes food down from the throat and into the stomach. Moving food by waves of muscle contraction called peristalsis.

8. The oesophagus
The partially digested food is pushed to the stomach by wave-like contractions known as peristalsis.
Circular muscles contract to push the food ball down.
Circular muscles relax, and the tube widens for food to move.

9. The stomach
Stomach
The stomach lining produces mucus and gastric juices which contains:
i) hydrochloric acid (acidic medium of pH 2 for enzymes and kills micro-organisms in food)
ii) Pepsin: hydrolyze protein to polypeptides.
iii) Rennin: hydrolyze milk caseinogen to casein.
stomach

10. Quick Revision: What is the function of hydrochloric acid?
1) Provides an acidic medium for activation of gastric enzymes.
Inactive forms
Prorennin HCl Rennin
Pepsinogen HCl Pepsin
2) Kills germs and potential parasites.
3) Stop the action of salivary amylase.
Active forms

11. Case Study 1 You should: take multiple small
meal at regular intervals,
take less protein per
meal
clean and cook the food thoroughly……
Dr. Jones, I am suffering from stomach cancer & half of my stomach was removed.
What should I do?

12. Case Study 2
Oh dear….i feel that my chest is burning after having a heavy dinner.
What could have gone wrong?

13. Inflamed
oesophagus
This condition is due to the irritation of the oesophagus that is caused by
too much stomach acid.

14. The Liver & Gall Bladder
A small pear-shaped organ that is greenish-yellow in colour.
Temporarily stores bile secreted by liver.
QUESTION:
Will bile secretion be hindered if the gall bladder is removed?

15. Liver and Gall Bladder Pancreas Small intestines Large Intestines
THE STRUCTURE & FUNCTIONS OF …
Liver and Gall Bladder
Pancreas
Small intestines
Large Intestines
Rectum and Anus

16. Largest gland in the body.
LIVER:
Largest gland in the body.
Lies below diaphragm, on right side of body.
Secretes bile.
QUESTION: Can bile digest food?
Bile is not an enzyme, so it cannot digest food but it aids in digestion of lipids.

17. Emulsification
Bile
Large oil drop
Small oil droplets

18. The Pancreas Connected to duodenum by pancreatic duct
Secretes pancreatic juice that contains digestive enzymes.

19. Small Intestines (Duodenum, jejunum and ileum)
Major site of chemical digestion of all remaining food (carbohydrates, fats and proteins).
Also, main site of absorption of nutrients occur here.

20. The Large Intestine Contains undigested food material.
Main function is to absorb water and mineral salts.
Rectum temporarily stores faeces that are egested through the anus.