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Skin is made up of three main layers. The epidermis comprises the top set of five layers and is about as thick as a piece of paper; the dermis is the second main layer and is more complex in structure. The third is called the subcutaneous layer and is made up of fat cells.

The epidermis’s main function is that of protection, as the top surface layers consist of dead skin cells and have no other direct function. Skin cells are constantly shed throughout the day and we lose hundreds of thousands every time we wash our hands, scratch or change clothes! The epidermis protects the underlying tissues from damage and also traps bacteria by secreting a sticky oil called sebum from glands deep in the hair follicle. Sebum is made up of cholesterol and acids and provides a natural moisturiser that gives suppleness to the skin. The acids are used to neutralise many types of bacteria and prevent internal infections. It is in the epidermis that we see physical ageing and the top visible layers of the skin can clearly mirror our inner imbalance or wellbeing.

n A cross-section of skin.

The epidermis’s slightly acidic pH is about 5.5–6 and this protective, mildly acid mantel also helps to ward off harmful infections and bacteria. The epidermis on the palms of the hands and soles of the feet are the thickest in the body and are therefore one of the most protected areas.

Under the epidermis lies the dermis, a layer of skin made up of blood vessels and fibres such as collagen and elastin. It is subdivided into two layers and here is where skin cells are reproduced and grow. The tissue is fresh, new and plump. Collagen in this layer gives the skin a youthful appearance. Skin also needs to move and stretch and this is made possible by elastin found in the dermis. It is a stretchy fibre which allows great movement of the skin. With age, both collagen and elastin diminish in function and so visible ageing of the skin occurs.

Nutrients, oxygen and water, which are vital for skin maintenance, are distributed in the dermis by the blood stream, and nerve endings are also stored here so we can feel textures, heat, cold and pressure easily.

Under the dermis we find the last of the three main layers of the skin: the subcutaneous layer. It is basically made of fat cells which give the body warmth and protection against external damage. Some subcutaneous layers are deeper than others but this necessary layer also protects muscles and bones from damage as well as acting as the body’s internal thermometer.

Together the epidermis and dermis weigh about 3 kg (7 lb), making skin the largest organ in the body. The skin combines together to form a very clever group of cells, as together they are responsible for protection, perspiration, sensation, heat regulation and excretion of unwanted bacterial invaders.

The back of the hands and feet have hair projections that trap air and keep us warm as well as being attached to senses which alert us to particles on the skin, as well as the heat or cold. This vellus hair can be very fine or very thick depending on nationality or hereditary genetics. The back of the hand is very susceptible to ageing, loose elastin and the breakdown of collagen, which, as time goes by, exaggerate the lines and wrinkles on our hands. The sun, too, damages skin texture, making it uneven and creating age or liver spots which once developed are very difficult to eradicate.