The Skin

The skin is generally made up of 3 layers: the epidermis, dermis and subcutaneous layer. The outermost layer of skin, known as the epidermis, acts as a relatively thin yet tough layer varying in thickness from 100 - 200 μm. The epidermis is said to have five of its own sub layers (in order of inner to outermost: basal layer, prickly layer, granular layer, transparent layer and horny layer) each playing a crucial role in the functionality of the avascular epidermis. A process of mitosis allows for the continual production of cells in the basal layer, known as keratinocytes. These are then pushed up through the epidermis by the newly formed cells on the surface of the basal layer. In the process of travelling through these sub layers, the cells change shape, gradually flattening and dying as they reach the upper layer, within approximately fourteen days. In this layer, the cells are said to be scale like in shape and contain a vast amount of keratin, a protein which protects the skin from harmful substances. The middle layer of skin, known as the dermis, is mostly made up of collagen, elastin and fibrilin, which gives skin its property of smoothness, strength and flexibility. It is structural divided into two layers, the upper papillary and the deep reticular layer. The upper papillary is named after the papillae that extend into the epidermis. These papillae create a bumpy surface which strengthens the connection between the epidermis and dermis. The deep reticular layer lies below the papillary region and consists of various interwoven fibres. This layer also contains hair follicles, blood vessels, special nerve endings (detecting heat, cold, pain, pressure and touch) and lymph vessels which act to enhance the skins functions. Although not generally regarded as a main layer, the subcutaneous layer is the deepest layer of skin consisting of a network of fatty tissue and elastic fibres which act to conserve heat in the body, whilst also acting as somewhat of a shock...