The skin barrier
The skin is the largest organ of the human body.
It has several layers including an outer layer (epidermis), an inner layer with blood vessels, nerves, hair follicles and glands (dermis), and a deeper fatty layer.
Skin plays a vital role in:
The skin barrier functions in two directions:
Most things that we come into contact with do not penetrate the healthy skin. In fact, there is a whole area of drug delivery research focussed on overcoming the formidable challenge posed by the skin barrier. Indeed, one approach that has been resorted to is disruption of the skin, for example using electrical charges, ultrasound and microneedles.
However, some chemicals are able to penetrate the skin. But these are limited to small molecules with particular, exceptional water and oil solubility characteristics.[2]
It is also known that the skin has a self-repairing mechanism. When the barrier function of the stratum corneum is damaged, the skin accelerates processes to repair the damage and restore the barrier properties.[1]
The skin is a remarkable organ, one that is well designed for the many functions it needs to perform.
Sources
[1] Denda, M. 2000, “Skin Barrier Function as a Self-Organizing System”, Forma, Vol. 15, pp 227-232.
[2] Finnin, B. C. 2003, “Transdermal Drug Delivery – What to Expect in the Near Future”, Pharmatech, pp 192-193.
It has several layers including an outer layer (epidermis), an inner layer with blood vessels, nerves, hair follicles and glands (dermis), and a deeper fatty layer.
Skin plays a vital role in:
- Providing a barrier to the outside environment – controlling what is allowed to pass into and out of the body and protecting against physical injury to delicate internal organs.
- Temperature regulation – pores in the skin open and close to regulate movement of gases and sweat across the skin.
- Insulation – the fatty skin layer helps insulate the body.
- Sense of touch – skin receptors send messages to our brain in response to stimuli.
- Production of vitamin D – one of the essential vitamins.
The skin barrier functions in two directions:
- Skin protects the body against water loss. Without this protection, all internal organs and cells would dry out and die. It is known that, in dry environments, the thickness of the stratum corneum increases which means that the skin further decreases water loss.[1]
- Skin provides the first line of defence against foreign substances. These include microorganisms such as bacteria and fungi, and chemical substances. The skin also provides protection against the harmful effects of ultraviolet light.
Most things that we come into contact with do not penetrate the healthy skin. In fact, there is a whole area of drug delivery research focussed on overcoming the formidable challenge posed by the skin barrier. Indeed, one approach that has been resorted to is disruption of the skin, for example using electrical charges, ultrasound and microneedles.
However, some chemicals are able to penetrate the skin. But these are limited to small molecules with particular, exceptional water and oil solubility characteristics.[2]
It is also known that the skin has a self-repairing mechanism. When the barrier function of the stratum corneum is damaged, the skin accelerates processes to repair the damage and restore the barrier properties.[1]
The skin is a remarkable organ, one that is well designed for the many functions it needs to perform.
Sources
[1] Denda, M. 2000, “Skin Barrier Function as a Self-Organizing System”, Forma, Vol. 15, pp 227-232.
[2] Finnin, B. C. 2003, “Transdermal Drug Delivery – What to Expect in the Near Future”, Pharmatech, pp 192-193.
