Skin

Skin is the general outer covering of the body, consisting of the epidermis and dermis (see figure). Below the dermis is the subcutaneous tissue (fiber). The skin performs many functions: protective, thermoregulatory, respiratory, metabolic, including participation in the exchange of vitamins, and is a blood depot (ed.).

The epidermis protects the body from injury and from invasion of various parasites. In addition, it protects the body from dehydration. The combination of erectile hairs, sweat glands and skin capillaries is part of the mechanism that regulates body temperature. If the body is overheated, then its cooling is accompanied by increased sweating and expansion of the capillaries passing through the skin. When the body is overcooled, the sweat glands lose their activity, the capillaries narrow and above the epidermis, due to the contraction of smooth myocytes associated with the hair follicles, the hair is straightened and an additional layer of air is formed between them.

The skin is also an organ of excretion (due to the secretion of sweat) and one of the sense organs - the organ of touch: it contains receptors that can perceive heat, cold, touch and pain. The layer of subcutaneous fat located under the dermis functions as a reservoir of water and nutrients.

Anatomical name: skin (cutis).

There is no more important organ for a person than the skin, since it is what protects our body from the effects of the external environment. In everyday life, we never think about what kind of organ this is. It is not difficult for scientists to explain to us what skin is, to give a complete description of its structure, appearance and the main functions that it performs. Skin is a structural and functional complex of tissues that covers the outside of the body. It consists of 3 layers: epidermis, dermis and subcutaneous fat. The epidermis is represented by multilayered squamous epithelium, consisting of several rows of cells. This layer performs a protective function, preventing foreign bodies from entering the body. The dacryogenic, sebaceous and sweat layers form the dermis. It is necessary to ensure thermoregulation of the body and metabolic processes. For the same purpose, the skin is penetrated by arterial networks and nerve fibers. A thin layer of adipose tissue in the dermis allows you to maintain a constant body temperature during unfavorable weather conditions and sudden changes in temperature. Subcutaneous fatty tissue in some places can reach up to 5 cm. The structure and physical properties of each layer are strictly individual. For example, the subcutaneous fat layer has its own innervation, blood supply and lymphatic drainage.

In addition to its protective properties, the epithelial layer of the skin plays an important role in the processes of touch and pain perception. Nerve endings located in this layer are susceptible to various types of stimuli. These include touch, pressure, heat/cold. The main disadvantage of sensitivity to single stimuli is the lack of information about the current situation at the moment of stimulation. Therefore, the skin is able to evaluate the holistic picture of everything that is happening. Trophic regulation is based on the coordinated work of blood and lymphatic vessels. The movement of blood through the veins occurs against gravity: it flows into the chest cavity as a result of muscle contraction. Moving up through large vessels, the blood is enriched with oxygen, nutrients, carbon dioxide, hormones, cell breakdown products, waste products, etc. The blood moves back through the arteries under the influence of gravity. Venous vessels emerge from under the skin at different levels and flow into deep or superficial venous networks. The discrepancy between the structure of the main and peripheral beds lies in the fact that the former are distinguished by a larger lumen diameter than small veins, which, on the contrary, correspond