Friday, December 7, 2012


1) Humans Breathe

We learnt that humans need air to breathe. When we breathe, we inhale (take in) and exhale (take out) air. Our chest moves up and down. The number of chest movement is the rate of breathing.

As we inhale, the chest rises outwards and upwards causing the chest to expand. The air is taken in through the nose, down the windpipe into the lungs. This air contains more oxygen.

As we exhale, the chest moves in causing the chest to contract. The air inside the lungs then flows out from the lungs to the windpipe and then out through the nose. This air contains more carbon dioxide.

Look at the diagram. Let us trace how air moves into the lungs and out of the lungs.

The red arrows show how air moves in and the blue arrows show how air moves out.
Humans use their lungs to breathe.

2) Animals Breathe

All animals breathe. Different animals may have different breathing structures. What are the differences in their structures? How do they breathe?

Animals have breathing structures to help them breathe. They need to breathe to stay alive.


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