The heart is a muscular organ about the size of a fist, whose job is to pump blood throughout the entire body. The heart has two sides, right and left, each with two chambers: an upper chamber (atrium) and a lower chamber (ventricle). These four chambers work together in a constant cycle to circulate blood in order to keep the body functioning:

  • The right atrium receives oxygen-depleted blood from the body and sends it to the right ventricle.
  • The right ventricle then sends the oxygen-depleted blood to the lungs to absorb more oxygen.
  • The left atrium brings oxygen-rich blood from the lungs into the left ventricle.
  • The left ventricle then sends the oxygen-rich blood out to the rest of the body through the largest blood vessel in the body, the aorta.
  • The circulated blood eventually returns to the right atrium and the cycle continues.

This video describes the normal function of a healthy heart.