The skin is a multi-layered outer covering of the body made up primarily of the epidermis, dermis and hypodermis (subcutaneous tissue). The epidermis is about 0.1 – 0.4 mm thick and is the outermost layer that provides a waterproof, protective wrap over the body and consists of several sublayers.
The dermis is the layer beneath the epidermis and is several times thicker.
It consists of connective tissue and cushions the body from stress and strain. The dermis has many nerve endings that provide the sense of touch and heat.
It contains hair follicles and glands such as sweat glands and blood vessels.
The hypodermis is rich in fat cells, and is not part of the skin, lying below the dermis. It’s purpose is to attach the skin to the bone and muscle and supplying it with blood vessels and nerves. It consists of loose connective tissue and elastin. The main cell types are fibroblasts, macrophages and adipocytes (the hypodermis contains 50% of body fat). Fat serves as padding and insulation for the body.
Overall, the skin regulates body temperature, the secretion of sebum and sweat, and respiratory and excretory systems. The skin has an important role as a sensory organ in terms of sensing temperature, touch, pressure, and pain.