Teeth at work

The idea

The initial breakdown of food into fine pieces by the teeth through crushing and chewing is called mechanical digestion.

Big bite, small bite

A chapati comes in one big piece. Your throat is narrow.

What do your teeth do to the big piece?

• Break it into fine pieces by crushing and chewing
• Turn it into water
• Keep it in one piece

Chew it

Press Chew four times. Watch the pieces.

Fine pieces

Each chew made more pieces, and each piece got smaller. This is the first step of digestion.

The initial breakdown of food into fine pieces by the teeth, through crushing and chewing, is called mechanical digestion.

Notes

The initial breakdown of food into fine pieces by the teeth, through crushing and chewing, is called mechanical digestion.

Check yourself

What is the first breakdown of food into fine pieces called?

Which body part does mechanical digestion in the mouth?

Mechanical digestion breaks food into …

How do the teeth break the food?

• Egestion. Egestion is passing stool out of the body.
• Absorption. Absorption is digested nutrients passing into the blood.
• Mechanical digestion — correct. Yes!
• The teeth — correct. Yes!
• The liver. The liver makes bile. It does not chew food.
• The lungs. The lungs are for breathing. They do not chew food.
• sugar. Breaking starch into sugar is done by saliva, not by chewing.
• fine pieces — correct. Yes!
• gases. Chewing makes food into smaller pieces, not into gases.
• By heating it. Teeth do not heat food. They crush and chew it.
• By freezing it. Teeth do not freeze food. They crush and chew it.
• By crushing and chewing — correct. Yes!