Excitable tissues in the human body include nervous, secretory and muscle tissue. However, the latter differs from the others in its unique property of contractility due to the presence in the cell structure of microfilaments from specialized proteins - myosin, actin, tropomyosin. This ensures the maintenance of the person's pose, movement in space, promotion of the food lump in the gastrointestinal tract, blood circulation and much more. Depending on the histological features, the functions performed and the origin, there is a classification for smooth and striated muscle tissue, and also for some features the authors sing out the third subspecies of the heart. However, it should be understood that the contractile elements form only the basis of these tissues, and they could not function fully without a dense network of blood vessels providing the delivery of a large amount of oxygen, a protective and energetically significant envelope, the sarcolemma, and a reinforcing loose unformed connective tissue.
Striped striped
Cross-striated muscle tissues, basically, make up all the skeletal musculature and provide movement of the joints and maintaining the posture. Their structural-functional unit is the sarcomere, and they consist, in turn, of myosymplasts - the fibers formed by the fusion of several separate cells in the process of differentiation. On the histological preparation, the striated muscle tissues can be easily distinguished by multinucleation and striation, which is why they got their name. Another important function is heat formation, and as a result of lowering the temperature, a person trembles. Also, the striated muscle tissue forms the structure of the myocardium, only the cardiomyocytes differ in the absence of symplasts. When microscopic, they are single-core fusiform cells. They are subdivided according to their functions into workers (predominate in number), conductive and secretory. It is thanks to the second, cardiac striated muscle tissues possess the property of automatism, that is, they have the ability to self-contract, which ensures the continuous operation of the heart. The third type of cells is a site for the synthesis of hormone-like substances, in particular this atrial natriuretic factor, which contributes to the enhancement of diuresis.
Smooth
If the human muscular tissue providing the movement is transversely striated, then peristalsis of the gastrointestinal and genitourinary tract, reduction of the vascular and bronchial wall provides smooth muscles. It is characterized by rhythmicity, relative slowness, high degree of extensibility and regenerative abilities, as well as vegetative innervation. This is an elongated form of single-nucleated cells, without striation, and with a large amount of actin and collagen in the structure. Each such myocyte is covered with a thin basal membrane, and the groups are endomizium from a loose unformed connective tissue.