The heart's four valves play a critical role in ensuring that blood flows smoothly through the heart, from the right atrium to the right ventricle, and from the left atrium to the left ventricle.
The tricuspid valve is located between the right atrium and the right ventricle. It has three cusps or flaps that open and close to control blood flow. When the heart muscle contracts, the tricuspid valve opens, allowing blood to flow from the right atrium to the right ventricle. When the heart relaxes, the tricuspid valve closes, preventing blood from flowing back into the atrium.
The pulmonary valve is located between the right ventricle and the pulmonary artery, which carries blood to the lungs. It is also composed of three cusps and works in a similar fashion to the tricuspid valve. When the right ventricle contracts, the pulmonary valve opens, allowing blood to flow into the pulmonary artery and on to the lungs. When the heart relaxes, the pulmonary valve closes, preventing blood from flowing back into the right ventricle.
The mitral valve, also known as the bicuspid valve, is located between the left atrium and left ventricle. It is named after the resemblance of its two cusps to a bishop's mitre or hat. The mitral valve opens when the left atrium contracts, allowing blood to flow into the left ventricle. When the ventricle contracts, the mitral valve closes, preventing blood from flowing back into the atrium.
Finally, the aortic valve is located between the left ventricle and the aorta, the largest artery in the body. The aortic valve has three cusps and works in a similar way to the pulmonary valve. When the left ventricle contracts, the aortic valve opens, allowing blood to flow into the aorta and out to the rest of the body. When the heart relaxes, the aortic valve closes, preventing blood from flowing back into the ventricle.