Skin Functions

The skin is a multifunction organ. Its structure is uniquely designed to enable it to undertake each of these functions and cope with a range of environments.

1) Barrier function
The skin is an incredibly effective barrier to the outside world – at its simplest, it keeps the outside world out and the inside in – quite literally it holds the human body together. However, the skin is not just a simple inert envelope; the barrier
it provides is complex and offers physical, chemical and immunological protection.

2) Physical protection
The analogy that is most commonly used to describe the physical barrier properties of the skin is that of a brick wall. In this instance, the layer that really is of interest is the horny layer of the epidermis. Corneocytes form the top layer of skin, these heavily keratinised cells need to be well-hydrated to form a complete barrier – they are the bricks in the wall. These bricks are ‘cemented’ with lipids. As the skin is constantly shedding, it is physically difficult for pathogenic
organisms to take hold.

3) Chemical protection
The surface of the skin is covered in commensal organisms. These ‘friendly’ bacteria and fungi live in harmony with humans and indeed offer a level of protection from pathogenic or disease- causing organisms. The commensals have
evolved to be able to thrive in the slightly acidic environment of the skin surface.
Skin cells are provided with inbuilt protection from UV radiation by melanin. In the upper layers of the epidermis, melanin is scattered throughout the cells providing protection, whilst in the lower layers the protection is specifically
targeted as the melanin granules form ‘umbrellas’ over the nuclei of the basal and spinous cells. Physical and chemical barriers form part of the body’s innate defence system.