How a Normal, Healthy Heart Works

It can be helpful to learn about your child's heart problem and how it affects them.

An easy way to gain this knowledge is to review how the normal, healthy heart works.

The Heart's Four Chambers

The heart is a strong muscle that acts as a pump. The pumping action causes the heartbeat or pulse.

The heart's four chambers are the left and right:

• Atria (upper part of the heart).
• Ventricles (lower part of the heart).

The wall that divides the right side of the heart from the left side is the septum.

The size of the heart is about as big as its “owner's" fist.

How the Healthy Heart Pumps Blood

>> See a diagram of how blood passes through the heart.

The heart pumps blood high in oxygen (red blood) to the body.

After the body uses the oxygen, the blood low in oxygen (blue blood) returns to the heart's right atrium. It then flows into the right ventricle.

The right ventricle pumps blue blood into tiny vessels in the lungs where it picks up oxygen and turns red. Red blood returns to the left atrium and flows into the left ventricle.

The left ventricle pumps blood into the aorta, which carries it to the body.

This process happens over and over again.

About The Heart's Valves

As blood moves in and out of the heart's chambers, it passes through four small "flaps" called valves.

With each heartbeat, the valves act as one-way doors that open and close so blood flows in the right direction. When a valve closes, blood can't pass through it.

There are two valves on each side of the heart:

• On the right are the tricuspid and pulmonary valves.
• On the left are the mitral and aortic valves.

The Heart's Blood Vessels

Blood travels to and from the heart in two types of blood vessels.

• Red blood that contains oxygen travels from the heart to the body through vessels called arteries.
• Blue blood without oxygen returns to the heart through vessels called veins.

As the heart pumps red blood to the rest of the body, it causes pressure in the arteries. This is how we measure blood pressure.

• Systolic blood pressure (the top number) measures the force against the arteries when the heart muscle contracts or beats.
• Diastolic blood pressure (the bottom number) measures the force in between beats when the heart muscle is at rest.

The Three Types of Heart Tissue

Three types of tissue make up the heart.

• The myocardium is the large muscle layer of the heart.
• The endocardium is the thin tissue that lines the inside of the heart.
• The pericardium is a thin elastic-like sac that the heart rests in.