The skin covers the human body and the body of many animals, and its main function is to resist microbes and prevent their entry into the body, and contains the sweat glands that help maintain the temperature of the body, and the nervous receptors in it, it helps to sense the cold, heat, And touch, the skin consists of three layers, we will mention in this article. The outer layer is called the epidermis. It is a physical barrier, characterized by its high thickness. The top part is called the corneal layer, which consists of a group of cells known as keratinocytes. These cells produce keratin, a solid protein, Keratinocytes die while living cells younger than the lower part of the skin rise to the surface. Older cells fall, and the skin regenerates once every four weeks. This layer protects the body from solar radiation. More precisely, melanocytes produce melanin, which gives the skin its color and protects it from ultraviolet radiation. The middle layer is called the crust, and is located directly below the skin, which is thicker than the previous layer, and contains blood vessels and lymphatic, collagen, nerves, hair follicles, and glands working on the secretion of fat and sweat, and play blood vessels in this layer a role in preserving Stability of the body temperature through the expansion or constriction. White blood cells guard the cortex, fighting the microbes that try to enter the body through the skin. Fibroblasts work to secrete collagen, which gives the skin its strength and strength. Elastin fibers give skin its elasticity. The inner layer consists of connective tissue, blood vessels, and cells that store fat. This tissue plays a role in protecting the body from blows or injuries. It contributes to the preservation of body temperature as well, and the fat in it increases by increasing the intake of food. The body has extra energy that consumes these stored fats. Types of human skin Dry skin: characterized by rough texture, and the appearance of tight, and narrow pores, and the secretion of sebaceous glands in this skin a little, and is characterized by its sensitivity to severe changes in the air. SKIN SKIN: It is a thick, glossy skin that produces a lot of fat and has good resistance to weather changes, but is more prone to the appearance of grains and pimples. Natural skin: It is a soft and flexible skin, usually a little fat on the chin and the base of the nose, due to the concentration of sebaceous glands in that area, but it is less fat on both cheeks and palms.
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