What are heart valves ?

Your heart is a strong muscle about the size of the palm of your hand. Your body depends on the heart’s pumping action to deliver oxygen- and nutrient-rich blood to the body’s cells. When the cells are nourished properly, the body can function normally. Just like an engine makes a car go, the heart keeps your body running. The heart has two pumps separated by an inner wall called the septum. The right side of the heart pumps blood to the lungs to pick up oxygen. The left side of the heart receives the oxygen-rich blood from the lungs and pumps it to the body.

The heart has four chambers 1), two on the right and two on the left:

  • Two upper chambers are called atrium (two is called an atria). The atria collect blood as it flows into the heart.
  • Two lower chambers are called ventricles. The ventricles pump blood out of the heart to the lungs or other parts of the body.

The heart also has four valves that open and close to let blood flow from the atria to the ventricles and from the ventricles into the two large arteries connected to the heart in only one direction when the heart contracts (beats). The four heart valves are:

  • Tricuspid valve, located between the right atrium and right ventricle
  • Pulmonary or pulmonic valve, between the right ventricle and the pulmonary artery. This artery carries blood from the heart to the lungs.
  • Mitral valve, between the left atrium and left ventricle
  • Aortic valve, between the left ventricle and the aorta. This aorta carries blood from the heart to the body.

Each valve has a set of flaps (also called leaflets or cusps). The mitral valve has two flaps; the others have three. Valves are like doors that open and close. They open to allow blood to flow through to the next chamber or to one of the arteries. Then they shut to keep blood from flowing backward. Blood flow occurs only when there’s a difference in pressure across the valves, which causes them to open. Under normal conditions, the valves permit blood to flow in only one direction.

The heart four chambers and four valves and is connected to various blood vessels. Veins are blood vessels that carry blood from the body to the heart. Arteries are blood vessels that carry blood away from the heart to the body.

The heart pumps blood to the lungs and to all the body’s tissues by a sequence of highly organized contractions of the four chambers. For the heart to function properly, the four chambers must beat in an organized way.

When the heart’s valves open and close, they make a “lub-DUB” sound that a doctor can hear using a stethoscope 2).

  • The first sound—the “lub”—is made by the mitral and tricuspid valves closing at the beginning of systole. Systole is when the ventricles contract, or squeeze, and pump blood out of the heart.
  • The second sound—the “DUB”—is made by the aortic and pulmonary valves closing at the beginning of diastole. Diastole is when the ventricles relax and fill with blood pumped into them by the atria.

Figure 1. The anatomy of the heart valves

heart valves anatomy

Figure 2. Top view of the 4 heart valves


Figure 3.  Normal heart blood flow


Figure 4. Heart valves function

heart valves function

Heart valves function

Blood Flow

  • The Right Side of Your Heart

In figure 3 above, the superior and inferior vena cavae are shown in blue to the left of the heart muscle as you look at the picture. These veins are the largest veins in your body.

After your body’s organs and tissues have used the oxygen in your blood, the vena cavae carry the oxygen-poor blood back to the right atrium of your heart.

The superior vena cava carries oxygen-poor blood from the upper parts of your body, including your head, chest, arms, and neck. The inferior vena cava carries oxygen-poor blood from the lower parts of your body.

The oxygen-poor blood from the vena cavae flows into your heart’s right atrium.  From the right atrium, blood is pumped into the right ventricle. And then from the right ventricle, blood is pumped to your lungs through the pulmonary arteries (shown in blue in the center of figure 3).

Once in the lungs, the blood travels through many small, thin blood vessels called capillaries. There, the blood picks up more oxygen and transfers carbon dioxide to the lungs—a process called gas exchange.

The oxygen-rich blood passes from your lungs back to your heart through the pulmonary veins (shown in red to the left of the right atrium in figure 3).

  • The Left Side of Your Heart

Oxygen-rich blood from your lungs passes through the pulmonary veins (shown in red to the right of the left atrium in figure 3 above). The blood enters the left atrium and is pumped into the left ventricle.

From the left ventricle, the oxygen-rich blood is pumped to the rest of your body through the aorta. The aorta is the main artery that carries oxygen-rich blood to your body.

Like all of your organs, your heart needs oxygen-rich blood. As blood is pumped out of your heart’s left ventricle, some of it flows into the coronary arteries (shown in red in figure 3).

Your coronary arteries are located on your heart’s surface at the beginning of the aorta. They carry oxygen-rich blood to all parts of your heart.

For the heart to work well, your blood must flow in only one direction. Your heart’s valves make this possible. Both of your heart’s ventricles have an “in” (inlet) valve from the atria and an “out” (outlet) valve leading to your arteries.

Healthy valves open and close in exact coordination with the pumping action of your heart’s atria and ventricles. Each valve has a set of flaps called leaflets or cusps that seal or open the valve. This allows blood to pass through the chambers and into your arteries without backing up or flowing backward.

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