| The normal heart
is a strong, hardworking pump made of muscle tissue. It is about the size of a person’s
fist. The heart has four chambers. The upper two chambers
are the atria, and the lower two are the ventricles (see figure). Blood
is pumped through the chambers, aided by four heart valves. The
valves open and close so that blood flows in only one direction.
The four heart valves are (1) the tricuspid valve,
separating the right atrium and right ventricle; (2) the pulmonary
(pulmonic) valve, between the right ventricle and the pulmonary
artery; (3) the mitral valve, between the left atrium and left
ventricle; and (4) the aortic valve, between the left ventricle
and the aorta. Each valve is made up of a set of “flaps”, also
called leaflets or cusps. The mitral valve normally has two
flaps, while the others have three.
Blood low in oxygen (illustrated in gray) flows
back to the heart after circulating through the body. It returns
to the heart through veins and enters the right atrium. This
chamber empties blood through the tricuspid valve to the right
ventricle. The right ventricle pumps blood through the pulmonary
valve into the pulmonary artery. From there the blood goes to
the lungs where it gets fresh oxygen (illustrated in red). Blood
returns in the pulmonary veins to the left atrium and then passes
through the mitral valve into the left ventricle. The left ventricle
pumps the red oxygen-rich blood out through the aortic valve
into the aorta. Blood then moves through the aorta into the
rest of the body.
*Modified from “If Your Child Has a Congenital
Heart Defect” by the American Heart Association. |
