In the middle of Asha's chest is a lump of muscle the size of her fist.

This lump of muscle is called the heart.

The heart in the middle of the chest, with a lung on each side of it.

A muscle squeezes and lets go.

The heart is a muscle. It squeezes and lets go again and again, all day and all night.

Each squeeze pushes blood out of the heart along tubes.

The tubes reach every part of the body: the brain, the fingers, the toes.

Other tubes bring the blood back to the heart, and the next squeeze pushes it out again.

The heart: a fist-sized lump of muscle, with tubes leading away from it.

A thing that pushes liquid along is a pump. So the heart pumps blood all round the body.

Blood goes out of the heart along the red arrow to every part of the body, and comes back along the blue arrow.