• The heart is a muscular organ in the chest.
  • It pumps blood through blood vessels by repeated, rhythmic contractions.
  • The heart has four chambers: two upper atria (singular, atrium) and two lower ventricles.
  • Valves between chambers keep blood flowing through the heart in just one direction.
  • The left side of the heart carries the oxygen-rich blood back from the lungs and pumps it to the rest of the body.
  • The right side collects oxygen-poor blood from the body and pumps the blood to the lungs.
Select from the frequently asked questions below