The skin

The skin has many purposes; it:

• acts as a barrier to protect the body from injury and keeps out infection
• keeps in necessary fluids and proteins
• protects the body from the harmful effects of ultraviolet light
• helps to control our body temperature.

Structure

The skin is divided into two main layers. The layer nearest the surface is known as the epidermis and the layer underneath is known as the dermis.

The epidermis contains three types of cells. On the surface are flat cells, known as squamous cells. Under the layer of squamous cells are rounder cells called basal cells. In between the basal cells are melanocytes.

The dermis contains nerve endings, blood vessels, and oil and sweat glands. It’s held together by a protein called collagen.

Structure of the skin

Melanocytes

Melanocytes are cells which produce a pigment called melanin. Melanin is responsible for the natural colour of our skin and protects it from the harmful effects of the sun. Melanocytes are found in the lower part of the epidermis.

When our skin is exposed to a lot of sun our melanocytes increase the amount of melanin to absorb more ultra violet rays. This makes the skin darker and gives it a suntanned appearance. A suntan is a sign that the skin has been damaged and is trying to protect itself.

People with brown or black skin have the same number of melanocytes but make more melanin. This means that they have more natural protection from the sun’s ultra violet rays.

Moles (sometimes called naevi) are just a group or cluster of melanocytes that lie close together. Most people with white skin have about 10–50 moles on their skin. Some young adults can have as many as 100.