The heart is a large, muscular sac located approximately in the middle of the chest, above the level of the breasts.
The heart is hollow, and the inside of the heart is divided into four separate chambers by thin, muscular walls. If you picture the heart as a simple square, there are two upper chambers and two lower chambers, all of which fill with blood at different times during the cardiac cycle. The top chambers of the heart are collectively called atria and the bottom chambers are called ventricles. The four chambers of the heart are the
- Right Atrium
- Right Ventricle
- Left Atrium
- Left Ventricle
The heart is the pump which drives circulation by contracting and squeezing blood out into the body.