The Skin

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The skin is the largest organ in the human body (both by surface area and weight – an adults skin is approximately 16% of the total body weight), serving as a protective barrier between the body’s internal environment and the external ambient environment. It controls our temperature and protects us from injury and many other environmental influences, but its ability to provide its own protection against the harmful effects of the sun’S UV radiation is limited.

The skin consists of two main layers, the outer and the inner layer.
The layer covering all is known as the ‘horny’ layer. The outer layer of this is the epidermis. It contains, among other things, cells including the melanocyte cell that produces melanin. Melanin gives our skin the colour we call a suntan. The inner layer beneath the epidermis is the dermis. It contains hair roots, sweat glands, blood, lymph vessels and nerves.

Cells
The human body is made up of millions of cells, which work together to perform different functions. They constantly reproduce themselves exactly, except when they have been damaged or are abnormal. This is the case with cancerous cells.

The Epidermis
The epidermis is the surface layer of the skin and is responsible for continuously making new skin cells. The new cells are made within the lower part of the epidermis and rise to the surface.

Approximately 95% of the cells in the epidermis perform this function, while the other 5% produce melanin. Melanin is the natural colouring of the skin and gives us our colour or tone depending on how dark we naturally are. The darker you are the more melanin your skin contains. When the skin is exposed to the sun we produce more melanin, as this is the skin’s natural sun protection. This makes us darker and this is what we call a tan.

If the skin is overexposed to the sun then it cannot produce enough melanin to protect itself, resulting in sun burn.

Melanocytes

Melanocytes are the cells in the epidermis and elsewhere that produce melanin. Melanin is the colour in the skin that makes us darker and is the skin’s natural sun protection. When melanocytes are overexposed to and damaged by UV radiation, melanoma or skin cancer results.

Basal Cells
These are small round cells found in the lower part of the epidermis – the first layer of the skin.

The Dermis
This is the innermost layer of the two that make up the skin. It contains the hair roots, sweat glands and blood cells. It also contains nerve endings that give the feelings of touch and pressure. The erector muscles also indicate closeness to the skin, wind and other environmental influences.

Subcutaneous Layer
The subcutaneous layer consists of a multitude of blood vessels that feed the dermal layer with the blood flow it requires. It also contains fat known as subcutaneous fat.