Our skin consists of three layers of tissues: the epidermis, the dermis and the subcutaneous layer. The epidermis is the paper-thin outer layer of the skin. The outer layer of the epidermis consists of dead cells that are always flaking or washing off. These are replaced by new cells manufactured in the lower portion of the epidermis, which move upward to the outside of the skin. As they do so, the cells harden and die. This cycle of cell production and replacement takes about 4-5 weeks.
The epidermis also contains melanocytes, the cells that contain melanin – the pigment that gives skin its color. Skin color is determined by the amount of melanin in these cells, not cell number. The more melanin, the darker the skin.
The dermis, the middle layer of the skin, contains blood vessels, nerves, hair follicles, sweat glands and oil glands. It makes up about 90 percent of the skin's thickness and is made up of collagen and elastic fibers that give the skin strength and elasticity.
The subcutaneous layer, the deepest layer of skin, is mostly composed of fatty tissue. It also contains blood vessels and nerves. The fat insulates the body from extreme heat and cold and provides a cushion to protect the body from injuries.