Cardiac Valves
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Valvular complex of heart
The heart plays a vital role in ensuring blood flows in one direction: from the atria to the ventricles, and then out to the body or lungs, without any backflow. This unidirectional flow is crucial for the efficiency and effectiveness of the circulatory system. A key component aiding this process is the heart’s valvular complex.
Valvular complex of heart consists of 2 sets of 2 valves that ensure blood flows in the correct direction, preventing any backward movement.
- The first set, the atrioventricular valves, includes the tricuspid valve and mitral valve. These valves act as gatekeepers between the atria and ventricles, ensuring that blood flows forward from the atria to the ventricles without returning.
- The second set, known as the semilunar valves, including the pulmonary valve and aortic valve, are located where blood leaves the heart for the pulmonary artery and aorta, respectively. Their main role is to stop blood from re-entering the heart from these vessels.
Tricuspid valve
Situated between the right atrium and right ventricle, is the atrioventricular valve known as the tricuspid valve. It ensures blood flows only from the atrium to the ventricle, not in reverse. Named for its typical structure, it features three cusps (flaps), hence the term ‘tricuspid.
During ventricular systole, which is the phase of the heartbeat when the ventricles contract, the tricuspid valve closes. This action prevents blood from flowing back into the right atrium from the right ventricle.
Mitral valve
Positioned between the left atrium and left ventricle, the mitral valve serves as the heart’s left side atrioventricular valve. It plays a crucial role in ensuring that oxygen-rich blood from the lungs flows smoothly from the atrium into the ventricle without backflow. In contrast to the tricuspid valve on the heart’s right side, the mitral valve typically features two cusps or flaps. This characteristic gives it the alternative name of the bicuspid valve
During ventricular systole—a phase of the heartbeat characterized by ventricular contraction—the mitral valve closes. This mechanism is crucial as it prevents the backflow of blood into the left atrium, ensuring efficient forward movement of oxygenated blood.
Pulmonary valve
The first semilunar we will examine is the semilunar valve of the right heart pulmonary valve.
It is positioned at the right ventricular outflow tract, right at the entrance to the pulmonary artery.
The pulmonary valve, equipped with three cusps, opens during ventricular systole to allow blood to flow from the right ventricle into the pulmonary artery. It closes during ventricular diastole, preventing blood from returning to the ventricle, ensuring efficient blood flow to the lungs for oxygenation.
Aortic valve
The second semilunar we will examine is the aortic valve of the left ventricle.
It is positioned at the outflow tract of the left ventricle, known as the aortic vestibule, marking the entrance to the ascending aorta.
This valve, equipped with three semilunar cusps, opens during ventricular systole, allowing oxygen-rich blood to flow from the left ventricle into the aorta. During ventricular diastole, the aortic valve closes, preventing blood from returning to the ventricle. This mechanism ensures efficient blood flow out to the entire body, maintaining a unidirectional flow critical for systemic circulation.