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The skin is a very important part of the human body as well as the largest. The skin has three layers of tissue, those are: epidermis, dermis and hypodermis.
The top layer is the epidermis, which is a very tiny layer and contains no blood vessels. Although it is very small it is made up of forty to fifty rows of stacked cells called squamous cells (or keratinocytes). The epidermis is responsible for producing keratin, which makes the skin waterproof. It also contains melanocytes which produce the melanin that give the skin color; Merkel cells, which are involved in touch; and Langerhans cells, which help the immune system fight foreign bodies. If a cell is pushed away from the deepest layer of the epidermis they eventually die because there is no more nourishment being received.
The second layer is the dermis and it has two layers to it. There is the papillary layer which consists of loose connective tissue, and the reticular layer which consists of dense connective tissue and is the deep layer. The function of these layers is to provide elasticity which allows the skin to stretch while also preventing wrinkling and sagging. The dermis layer is where the ending of blood vessels and nerves stay, and where the structure for hair is. It also houses the sweat glands and oils glands which come from hair follicles. This layer also houses the lymph vessels, which supply clear fluid containing white blood cells from the immune system to fight off infections and foreign bodies.
The final and deepest layer of the skin is the hypodermis. It is composed of connective tissue (or adipose tissue) which stores excess energy as fat. This layer helps insulate the body and cushions the internal organs. It is also responsible for connecting the dermis layer to muscles and bones. The blood vessels, lymph vessels, nerves and hair follicles from the dermis layer also run through this layer.
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