Valves: structure and characteristics
The morphology of the heart valves has long attractedattention of researchers. Violation of the architectonics or the operation of any part of the valve apparatus leads to a violation of the closing function of the valve and the pumping activity of the heart as a whole.
General principles of the structure of atrio-ventricular septums
Valvular valves contain fibrous rings, valves, chords and papillary muscles.
Valve rings are fibrous formation with the inclusion of muscle elements, which are internally covered with endocardium. Valves valves are covered with endothelium and have a layered structure.
In the direction from the atrial to the ventricular surface, there are 3 layers:
The basis of the valve is a fibrous plate, which comes from a fibrous ring.
Valves, or rather their spongy layer,narrow, has many elastic fibers in the connective tissue, which are concentrated mainly along the free edge of the valve. Relatively more elastic fibers in the petals of the bicuspid valve than in the tricuspid.
In the ventricular layer, collagen fibers predominate.
Valvular valves have two surfaces - atrial and ventricular, and two edges - attached and free.
The area of atrioventricular valves of male hearts is larger than the area of the same valves in female organs. The tricuspid valve of the area is larger than the bicuspid valve by approximately 25%.
Papillary muscles with tendon chords form a subvalvular apparatus of the heart. The chords are attached to the flaps. The length and thickness of them reaches their maximum by 35-40 years.
The number of leaves (petals) is from 2 to 6. Main:
- the front, usually one, sometimes is divided into two parts;
They are always large.
The front leaf is triangular in shape, attached tothe upper-medial third, the posterior to the rest of this valve, it differs in a rectangular shape. Both have a smooth basal and rough apical zones, separated by a crest.
The front lobe of the mitral valve inthe functional ratio is basic, it is more mobile, during the systole it is the main load, as it experiences the pressure of the bulk of the blood ejected by the ventricle.
The rear is more involved in closing the valve. Its functional significance is less.
Valves valves are chordally fixed to the papillary muscles.
- are intertwined from the ventricular side of the valves into the rough zones, each split into three thinner threads.
To the front lobe, which has a 2-leaf valve, 5-10 chords are attached from the papillary muscles, 10-20 to the posterior, and sometimes 20 to 30 tendon filaments.
The left atrio-ventricular opening at the level of the fibrous ring has a slightly oval shape.
With regard to the number of leaflets (petals) and theirsizes in this structure, there is also no consensus. It is generally accepted that it consists of 3 leaflets and a different number of segments or intermediate valves. With age, the number of petals increases due to splitting of the main plates into smaller ones.
The valves of the right atrio-ventricular valve represent a duplicate of the endocardium, which lines the right atrium and ventricle.
The right ventricle, correspondingly to 3 valves, hasusually three groups of papillary muscles. They come from the myocardium of the right ventricle (the anterior one is the most powerful, then the posterior and septal). The number of these muscles, the size and shape of people are not the same. Each papillary muscle sends 2-4 chords, which, branching, attach to the lower surface and the edges of valve flaps. Small intermediate valves are attached to the wall of the ventricle.
Studies of heart valves have a fundamental basis.
The last few years clarified the issues of blood supply to the valves and their ontogeny.
Thus, in this article we considerthe question of the structure of the heart valves, including two- and three-leaved valves. This information will be useful for students of medical institutions, as well as for those who only wish to enter this specialty. Moreover, students who study biology and anatomy, information about what valve valvular heart, will also be very interesting.