Inside the Heart and Its Vessels

Your heart is a muscular pump that pushes blood around your whole body without ever stopping. Arteries carry that blood away from the heart, and veins bring it back.

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In the picture

The thick muscular wall of the heart, cut open to show its four chambers; it squeezes to push blood out.
The wide red artery arching out of the top of the heart, carrying blood away under high pressure.
The broad blue vein returning blood from the body into the heart at low pressure.
The magnified mesh of hair-thin capillaries in the fingertip, where blood hands over oxygen and changes colour.

Examples

Pressing two fingers on your wrist to feel your pulse — that is an artery swelling each time the heart squeezes.
The bluish lines you can see under the skin on the back of your hand are veins carrying blood back to the heart.

Key takeaways

Arteries carry blood away from the heart; veins carry blood back to it.
A resting heart beats about 60 to 80 times a minute, roughly 100,000 times a day.