chap 02_2-3

Human Digestive System

Digestive system

Chapter

2.3

mouth

rectum

liver

gall bladder

large intestine

small intestine

pancreas

stomach

oesophagus

salivary glands

anus

duodenum

1

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TRG Science Form 2

Chapter 2 : Nutrition

Chapter

2.3

Digestion start hereTeeth chewed and breakdown the food into small piecesSalivary amylase changes starch into maltose (complex sugar)
starch

maltose

salivary amylase

Mouth

2

Physical Digestion Stage


TRG Science Form 2


Chapter

2.3

The salivary gland secretes saliva that is alkaline and contains salivary amylase
enzymes

Salivary gland

3

Chemical Digestion Stage


TRG Science Form 2


Chapter

2.3

Food passes through the oesophagus into the stomach by peristalsisNo digestion takes place in the oesophagus
Oesophagus

4


TRG Science Form 2


Chapter

2.3

Food is mixed with gastric juice Gastric juices containhydrochloric acidHydrochloric acid helps tokills bacteriaprovide an acidic medium for enzymes to take actionneutralize and stop the action of salivary amylase enzymesPepsin changes protein into peptonesRennin coagulates milk in the stomach
to help in the enzymic action of pepsin

protein

peptones

pepsin

liquid milk

protein

solid milk

protein

rennin
enzymes pepsin and rennin
Stomach

5


TRG Science Form 2


Chapter

2.3

The first part of the small intestineReceives pancreatic juice and bilePancreatic amylase changes
starch into maltose
Pancreatic protease changes
peptones into amino acid
Pancreatic lipase changes fat
into fatty acid and glycerol
The bile breaks down fats into small droplets for enzymic action
starch

maltose

pancreatic amylase

peptones

amino acids

pancreatic

protease

fat

fatty acid + glycerol

pancreatic

lipase

Duodenum

6


TRG Science Form 2


Chapter

2.3

Produces bile and stored in the gall bladder before it is flows into the
duodenum through the bile duct
Bile helps to prepared an alkaline medium for enzymic action
Liver

7


TRG Science Form 2


Chapter

2.3

Produces pancreatic juice that contains three types of enzymespancreatic amylaseproteaselipase
Pancreas

8


TRG Science Form 2


Chapter

2.3

The small intestine produces enzymes which changes maltose into glucoseDigestion is completed in hereThe nutrients is absorbed through the thin walls of the small intestine into the
bloodstream

Small intestine

9


TRG Science Form 2


Chapter

2.3

Water is reabsorbed hereUndigested and unabsorbed food goes to rectum
Large intestine

10


TRG Science Form 2


Chapter

2.3

Undigested and unabsorbed food forms a semi solid waste called faecesTemporarily stored the faeces
Rectum

11


TRG Science Form 2


Chapter

2.3

Excreted the faeces out of the body
Anus

12


TRG Science Form 2


Quick Refresh

Digestion is the process of breaking down complex food into simple diffusible molecules that can be absorbed by the body

Enzymes are proteins which speed up the process of digestion

Alimentary canal is the path of the food passes through the digestive system. It start from mouth, oesophagus, stomach, small intestine, large intestine, and ends at the anus

Process of peristalsis is the movement of food by the muscular walls that contract and expand alternately along the alimentary canal

As a result of digestion

Q.R.

2.3

Class of food

Final product

Carbohydrate

Glucose

13

Protein

Amino acid

Fat

Fatty and glycerol


TRG Science Form 2


chap 02_2-3

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