The skin forms the outer boundary layer between the human being and the environment, and in this highly exposed place acts on the one hand as a barrier, and on the other as a link between the outside world and the internal organs. With an area of approximately 2 meters, it is the largest organ in the body and must fulfill a large number of vital tasks.
When the surface is intact, the skin prevents the loss of body fluids. It has a great capacity for resistance and preserves the internal organs from attacks that may be caused by external factors. It protects against the invasion of microorganisms and can resist to a certain extent the damaging influences of certain chemicals and UV rays.
The skin has its own cycle of renewal. Skin cells regenerate continually in the deepest layer of the skin and travel to the surface, replacing old cells. However, with age, the rate of cell renewal decreases, causing changes in skin conditions.
Muscle cells are highly specialized and are called muscle fiber. The cytoplasm is designated as sarcoplasm and the cell membrane as sarcolemma. The cytoplasm is full of myofibrils made up of alternating actin and myosin filaments that, when they slide past each other, give the cell contractile capacity. Muscle cells are much longer than they are wide, they are often called muscle fibers, but they should not be confused with the intercellular substance form, that is, collagen, reticular, and elastic fibers, since the latter are not alive.
Depending on its location and different structural characteristics, muscle tissue is divided into three types: skeletal muscle tissue, cardiac muscle tissue, and smooth muscle tissue. Skeletal muscle can contract or relax voluntarily, while smooth muscle and cardiac muscle contract involuntarily or automatically.
There are many diseases that can occur in the skin and muscles, hence the importance of preventing them by providing the necessary nutrients for the cells that make up the dermal and muscular system, preventing symptoms of skin aging and muscle flaccidity from appearing at an early age that only in appearance represents for the population old age.