The muscular system is one of the most important biological subsystems with which the body performs various movements.
It can be represented as a combination of muscle fibers capable of contraction. Fibers are connected together in bundles that form muscles as special organs, or enter the internal organs themselves. Muscle mass is much higher than other organs: in some animals, it makes up 50 percent of the total body weight, and in humans - 40 percent. The muscular system converts chemical energy into heat and mechanical energy.
Muscular system
In vertebrates, muscle is divided into the following groups:
- Somatic, enclosing the innards and forming the muscles of the limbs. Skeletal muscles belong to it.
- Visceral (part of the viscera). This is smooth and hearty muscles.
Human muscular system
Skeletal muscles are arbitrary and striated. They are attached to the bones and are cylindrical fibers 1-10 cm long.
Each muscle fiber is an undifferentiated cytoplasm (sarcoplasm) with a large number of nuclei located on the periphery. The periphery includes differentiated striated myofibrils. The periphery is surrounded by a transparent membrane (sarcolemma), which includes collagen fibrils. A small group of fibers is surrounded by endomysium; large muscle joints are bundles of fibers enclosed in internal intermissions; each muscle is surrounded by an external remission. Muscular and connective tissues of each other continue and are interconnected. The entire muscle is enclosed in a case called fascia. The muscular system consists of muscles, each of which is connected to and penetrated by nerves and blood vessels.
Muscles help maintain the balance of the body, carry out movement in space and the vital movements of all parts of the body.
Smooth muscles are located in the walls of blood vessels and internal organs. The length of the muscles of this species is 0.02-0.2 mm. They are striated, their shape resembles a spindle. Smooth muscle cells have an oval nucleus in the center.
Smooth muscles facilitate the transport of what is contained in the hollow organs (food in the intestines, for example). They participate in the regulation of pressure, the expansion and contraction of the pupil, and other movements in the body. The autonomic nervous system is responsible for smooth muscle contraction.
The muscular system also includes the heart muscle, which is only in the heart walls. It is continuously reduced throughout life, providing blood circulation through the vessels and nourishing the necessary tissues and organs.
Musculoskeletal system
The human body contains about 400 striated muscles, which contract under the control of the central nervous system.
The musculoskeletal system includes muscles, bones, tendons, joints, ligaments and cartilage, which make up almost 75% of a person’s weight. This system gives the human body a certain shape, allows it to stand and move. The skeleton is the skeleton for organs and tissues, it also reliably protects important organs from damage. Minerals such as phosphorus and calcium accumulate in bones. The inside of the bones is represented by bone marrow participating in the formation of all blood cells (red blood cells, white blood cells and blood platelets).
With injuries and diseases of any part of the musculoskeletal system, the statics and dynamics of the whole organism are disturbed. In addition to the fact that the entire musculoskeletal system suffers, the internal organs also cease to function properly. For example, when one of the limbs is shortened, the spine bends, which causes deformation of the chest, as a result, the circulatory and respiratory organs suffer.