Your heart is a muscle. Just like any muscle in your body, your heart needs
blood and oxygen in order to work. It can also get stronger and weaker depending
on your fitness level.
However, the heart is much more important than the rest of the muscles in your
body. The heart's purpose is to pump blood around the body and supply your organs,
joints, and muscles with oxygen.
How does my heart work?
Your heart has four chambers. It has two "atria" and two "ventricles",
with one atrium and ventricle on the right and one atrium and ventricle on the
left.
