Page 127 - Primary Five Science

Chemical digestion is where food is broken down to sim-

pler soluble particles by action of enzymes. These en-

zymes are secreted by digestive system organs.

Characteristics of Enzymes

 They are proteins in nature

 Each enzyme works only on specific types of food

 They work within a specific temperature range

 They work under alkaline or acidic conditions. e.g.

acidic environment; Ptyalin, amylase, lipase, Tryp-

sin. alkaline conditions; Pepsin, Rennin,

This is muscular tubing of the digestive system ex-

tending from the mouth to the anus. It is composed of

the following organs.

Ingestion:

This is the actual taking in of food (through the mouth)

Digestion:

This is the breaking down of food both physically and chemically

to simpler substances that can be absorbed by the body.

Absorption:

Is the taking in of digested food from the digestive tract to the

blood stream.

Egestion

Is the removal of undigested food from the body