The muscular system corresponds to the set of muscles present in the body that allow the movements to be carried out, as well as guarantee posture, stabilization and support of the body. The muscles are formed by a set of muscle fibers, the myofibrils, which are organized in bundles and surrounded by tissue.
The muscles are able to perform the movement of contraction and relaxation and this is what favors the performance of daily movements, such as walking, running, jumping, sitting, in addition to others that are essential for the correct functioning of the body, such as circular the blood, breathe and perform digestion.
Classification of muscles
Muscles can be classified didactically according to their structure, function and contraction characteristics. According to their contraction characteristics, the muscles can be:
- Volunteers, when their contraction is coordinated by the nervous system, which is influenced by the person's desire; Involuntary, in which the contraction and relaxation of the muscle does not depend on the person's will, happening on a regular basis, as in the case of the cardiac muscle and the muscle present in the intestine that allows peristaltic movements, for example.
According to their function, they can be classified into:
- Agonists, who contract in order to generate the movement; Synergists, who contract in the same direction as the agonists, helping to produce the movement; Antagonists, who are opposed to the desired movement, that is, while the agonist muscles are generating the contraction movement, the antagonists promote relaxation and gradual stretching of the muscle, allowing the movement to happen in a coordinated way.
In addition, according to structural characteristics, muscles can be classified as smooth, skeletal and cardiac. These muscles act directly connected with the nervous system in order to allow the movement to happen in a correct and coordinated way.
Muscle types
According to the structure, muscle tissue can be classified into three different types:
1. Cardiac muscle
The cardiac muscle, also called myocardium, is the muscle that covers the heart and allows the movements of this organ, favoring the transport of blood and oxygen to other organs and tissues of the body, maintaining the proper functioning of the body.
This muscle is classified as involuntary, because its function is performed regardless of the person's desire. In addition, it has striations, which can also be called a cardiac striatum, and consists of elongated and branched cells that contract vigorously and rhythmically.
2. Smooth muscle
This type of muscle has an involuntary and slow contraction and can be found in the wall of hollow organs such as the digestive system, bladder and artery, for example. Unlike the cardiac muscle, this muscle has no streaks and, therefore, is called smooth.
3. Skeletal muscle
Skeletal muscle is also a type of striated muscle, however unlike other types of muscle, it has voluntary contraction, that is, for movement to occur, the person must give this signal for the muscle to contract. This type of muscle is attached to the bones through the tendons, allowing the movement of the muscles of the arm, legs and hands, for example.
