Synonym: Valvae cordis
Definition
The heart consists of four cavities, which are separated from each other and from the respective blood vessels by a total of four heart valves. This allows blood to flow in only one direction and only when it is appropriate within the scope of the heart action (systole or diastole). The heart valves are divided into two sail valves and two pocket valves.
Anatomy and Function
The heart valves are anchored in the so-called cardiac skeleton, a fiberboard between the atrium and the ventricle. They are protrusions of the endocardium, i.e. the innermost layer of the heart wall, and ensure that blood can only flow in one direction (unidirectional) through the heart. They also allow blood to flow only at certain times of the heart’s action.
They also function heart. There are two sail valves (Valvae cuspidales) and two pocket valves (Valvae semilunares). The sail valves are also known as atrioventricular valves (AV valves) because they are located between the atrium and the ventricle.
The naming of the heart valves is based on the number of sails. The AV valves prevent blood from flowing back from the ventricle into the atrium during systole, when the ventricle is under tension. The sail valves are connected to the papillary muscles via tendon threads (chordae tendineae).
These are anchored in the wall of the ventricle and ensure that the valves do not strike back too far into the atrium when they close and during the tensing phase. The two pocket valves or semilunar valves are each located between the ventricle and the draining vessel. Thus, the pocket valves prevent the blood from flowing back from the two large vessels into the chambers after systole has ended.
Their name comes from the fact that they each consist of 3 crescent-shaped (semilunar – crescent-shaped) sacs or pockets.
- The tricuspid valve is the AV valve between the right atrium and ventricle. (tri- three, cuspis sail)
- The bicuspid valve (bi – two, cuspis – sail), also called mitral valve, is located between the left atrium and the ventricle.
The additional designation of the bicuspid valve as mitral valve comes from the fact that it resembles a mitre with its two sails.
- In the right heart it is the pulmonary valve, which is located between the right ventricle and the pulmonary trunk (the beginning of the pulmonary tract).
- In the left heart, the aortic valve separates the left ventricle from the aorta.
The heart action can be divided into diastole (relaxation and filling phase) and systole (tension and ejection phase). In the past it was assumed that the closing of the AV valves at the beginning of systole would produce the first of the two heart sounds. Nowadays, however, it is generally accepted that the first heartbeat is only produced after the AV valves have closed, i.e., when the ventricular muscles are tensed.
The 2nd heartbeat, on the other hand, is actually a valve closing tone. It is produced by the closing of the pocket valves at the end of systole, i.e. after the blood has been ejected from the ventricles into the pulmonary or body circulation.
- In the first part (diastole) the heart muscle relaxes and the atria fill with blood.
At the same time, both the valves between the atrium and the ventricle (AV valves) and the valves between the ventricles and the draining vessels (semilunar valves) are closed.
- Then, in the second part of diastole, the AV valves (bicuspid and tricuspid valves) open and the chambers are filled with blood.
- Systole begins with the contraction (tensing) of the chamber muscles. At first, the AV valves close to prevent backflow into the atrium.
- Then the pocket valves (pulmonary and aortic valves) open and the blood is pumped into the pulmonary or body circulation. When the pocket valves are closed, diastole begins again.
