Inside the Heart and Its Vessels

In the picture

1. 1The thick muscular wall of the heart, cut open to show its four chambers; it squeezes to push blood out.
2. 2The wide red artery arching out of the top of the heart, carrying blood away under high pressure.
3. 3The broad blue vein returning blood from the body into the heart at low pressure.
4. 4The 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.

Quiz: Inside the Heart and Its Vessels (Age 13)

1. 1

   What is the heart’s main job in the body?

   • To pump blood so it keeps moving around the whole body
   • To store blood until the body needs it
   • To make fresh blood to replace what is used up
2. 2

   A blood vessel is carrying blood away from the heart under high pressure. What kind of vessel is it?

   • A vein
   • An artery
   • A capillary
3. 3

   Where does blood hand its oxygen over to the body’s cells?

   • Inside the chambers of the heart
   • In the wide arteries close to the heart
   • In the tiny capillaries spread through the tissues

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.