What are the structure of the skin and its main layers?
The skin is a complex organ covering a surface area of approximately 2M2 and weighing nearly 3-4kg, it is one of the body’s largest organs. The skin is one of few organisms within the body that self- reinstates and repairs along with hair and nails. It can indicate aspects of a persons’ health and has a strong correlation linked to diet and lifestyle. The skin, also known as the ‘Integumentary System’ is the only barrier a person has against the outside world and environmental effects such as harmful substances and abrasions, moreover skin contains other vital tissues and organs that prevent dehydration, internal tissues from exposure to trauma, ultraviolet radiation and provide synthesis and storage of essential vitamins. Other integral functions include sensory perception, immunologic surveillance, and thermoregulation in the first instance. To begin to understand the essential role skin plays in tissue integrity, we need first to understand its structure and function.
The skin is made up of two main layers and subsequent sub-layers. The two main layers are the epidermis, and dermis which rest on a fatty subcutaneous layer called the panniculus adiposus. These layers are made up of a superficial cellular layer of tissue that provides a robust protective outer surface and basal (deep) regenerative and pigmented connective tissue layer, known as the dermis.
The epidermis consists of a fibrous protein called keratin which is continually renewed and replaced via cell division instead of new cells from the basal layer. This process plays a vital role in tissue integrity as it renews the epidermis of the entire body every 25 to 45 days. Simply, box-like cells multiply from the basal layer rapidly and gradually moving towards the surface as they are forced upwards from new cells below. As this process continues to move cells upwards, they begin developing tiny ‘prickles,’ which bind together tightly and eventually flatten and fill with the protein, ‘Keratin.’ Finally, the cells die upon reaching the surface fully keratinized, resembling flaky inter-locked scales. As the cells die and wear away they are replaced with new cells as the process of skin renewal begins all over again. The entire journey can take up to four weeks.