Lunar valves - their definition is given in this article. In addition, having read the information below, you can find out about the operation of such valves in the human body, about their structure, about the places in which they are located. Information, no doubt, will be of interest to anyone interested in human anatomy.
Valve definition
In the body, which is a complex mechanism, there are many devices in order to direct flows in the right direction. Such devices are located in the heart muscle - they are more complex. They are also located in capacitive vessels of various calibers.
The valve apparatus is a set of anatomical structures that, when working together, interfere with the reverse (retrograde) movement of blood.
Varieties of Heart Valves
- The first group is the structures that separate the ventricles and atria.
- The second group consists of valves located at the junction of the aorta and the trunk of the pulmonary artery, in the zone where these vessels leave the ventricles of the heart.
Aortic and pulmonary valves have the following structures:
1. Lunar flaps (lunar heart valves).
2. The spaces between the shutters (inter-shutter triangles).
3. Sinuses.
4. Fibrous rings (whose existence is discussed).
Lunar flaps
Since only the flaps included in them have a lunar shape in these valves, it is correct to call these valves the aortic valve and the pulmonary trunk lunar valve. Both valves have three shutters. The aortic valve has a right, left, and posterior flap. And the valve of the pulmonary trunk instead of the back - the front.
The sizes of the dampers differ in people of different ages, there are also individual characteristics. As a rule, the width of the lunar aortic flaps is wider than the aortic sinuses, and in height they, on the contrary, are smaller. This structure contributes to their displacement down and closing of the valve when filling them with blood. The coronary artery mouths are located in the sinuses of the aorta.
Semilunar valves are located near the fibrous ring. They are formed by an endocardial fold. There are front, left and right sickle-shaped dampers. Their undersides are connected to the ends of the sines. The flaps and sines form the dimples. Crescent-shaped valves are slightly larger in size than the sinuses of the pulmonary trunk.
Sinuses of the aortic valve and pulmonary valve
The sinuses of the aorta and pulmonary artery are the spaces between each of the lunate valves and the vessel wall.
The height of the aortic sinuses of adults is 1.7-2 cm, their depth is from 1.5 to 3 mm. Deepening of the sinuses occurs with age. The spaces between the flaps located next to each other have the form of triangles, with the base facing the ventricles. Triangles consist of collagen and elastic fibers, they connect the dampers to each other and form the fibrous rings of the valves.
At the base of the aorta, an oval fibrous structure with three teeth is formed, resembling a crown.
In the composition of the pulmonary trunk , three sines are usually distinguished: front, left and right. Sometimes there are two sinuses. The sizes of these sinuses differ significantly in different age groups, and also have individual characteristics. In adults, the left sinus is 19-32 mm wide, 12-16 mm high, the right 20-32 mm and 10-15 mm. Front 20-30 mm and 10-15 mm, respectively.
Not everyone recognizes the existence of a fibrous structure at the base of the pulmonary trunk.
Valve mechanism
A crescent-shaped lunar valve prevents blood from returning to the ventricles.
During the contraction of the heart muscle, the blood in the ventricles moves in two directions: towards the lunate flaps, and towards the atria. Having reached the atrioventricular valves, blood strikes against them, and the valves slam shut. The pressure in the cavity of both ventricles increases. Pressure on the crescent-shaped lunar valve rises and exceeds that in the aorta and pulmonary artery. The only way out of the blood is through flow to the aorta, and from the right ventricle to the pulmonary trunk. In this situation, the flap valves are closed and the lunar valves are open.
When the current from the cavity of the left ventricle rushes towards the aorta, then this current presses the lunar flaps against the wall of the aorta. After the expulsion of blood from the cavity of the ventricle, the aortic sinuses are closed. There is relaxation of the ventricles, and the blood thrown into the artery tends to reverse to the heart, to the left ventricle. The sinuses of the artery are filled with blood, and the sickle-shaped valves of the aorta are covered. Blood does not flow back into the cavity of the ventricle.
The pulmonary lunar valve also works.
Aortic and pulmonary valves inhibit the backward movement of blood from large vessels into the ventricular cavity at the end of systole.
Lunar valves
In the body, there is a variety of semilunar valves, which have a simpler structure than heart valves, but their function remains the same. These are structures that prevent the retrograde movement of blood.
Lunar valves are located in some veins (legs, upper limbs), as well as in the lymphatic vessels.
The venous system is represented by a network of resistive vessels, the function of which is to transport blood to the right heart against earth's gravity. The vessels of the venous system have a less developed muscle membrane than in the arteries. They have different mechanisms for supplying blood from the lower parts to the heart. One of the adaptive mechanisms is the presence of lunar valves.
Vein valves have two valves, valve rollers and parts of the vessel wall. Valve structures in a greater number are located in the veins of the legs. For example: a large saphenous vein has up to ten venous valves.
Pathology
If the integrity or function of the valves is impaired as a result of trauma or inflammation, pathological conditions develop that need to be recognized and proper therapy initiated (acute or long-term cardiac inferiority in case of damage to the heart valves).
A known vein pathology associated with a violation of the valves is varicose leg disease, which is dangerous for its complications (thrombophlebitis, leg swelling, obstruction of the pulmonary artery). Currently, modern medicine has a number of effective methods for restoring the normal functioning of the body, in particular, the valves in question. Naturally, in each case, an individual approach to a sick person is determined.
Thus, we examined the functions of semilunar valves, their role in the overall functioning of the human body, problems that can be impaired and pathologies associated with valves.