Muscles are made up of muscle tissue, which tends to contract under the influence of nerve impulses. They are able to convert the energy of chemical reactions in the body into mechanical work.
There are two types of muscles: smooth and striated. Smooth muscles make up the majority of human musculature, they are part of the internal organs and walls of blood vessels. The striated (skeletal) muscles are attached to the bones of the skeleton. All of them form the human muscular system, which makes up forty percent of the total body weight. With the help of muscles, a person can perform a number of important physiological functions. Move your body in space. Due to the muscles, respiration, blood circulation, movement of food through the digestive organs, maintenance of blood vessels in tone, excrement, etc.
The most important function of muscles is hydrokinetic, with the help of its blood can move through the body. All striated muscles are involved in this process. The skeletal muscles also aid in the movement of blood. During any activity, due to the alternation of contraction and relaxation of skeletal muscles, blood is pushed out of the venous vessels located in the muscles and moved in the desired direction. During rest or sleep, muscles continue to move blood. This is due to the ability of the muscles to tremble with great frequency, a rarefaction is formed in the veins, which makes the blood move. This feature is the most important. A person could not live without this muscle ability. The bedridden person, who has been deprived of all movement by the disease, continues to live only thanks to this muscle function.
The second function of the muscles is posture. It aims to maintain a certain position of the body and its parts while others are moving. For example, the muscles of a person sitting at a table do static work to maintain a fixed body position.
The third function of the muscles is phasic. It provides movement. Thanks to this function, a person can walk, jump, run - in a word, move in space. Also, muscles store energetically valuable material and are a source of heat. If a person has trained strong muscles, then they can protect the internal organs and bones of a person from external injuries.