Our skin is the largest organ we possess and not only protects us from
injury and infection but keeps the body's temperature and moisture content
stable at all times.
The skin is much more than a simple wrapping around our body. It is a
living and versatile organ and, as such, reflects the age and state of
health of the body it encloses. In addition to protecting and cushioning the
body and forming a waterproof barrier on the outside, the skin also seals in
moisture, eliminates body waste into the atmosphere and keeps harmful
bacteria and viruses at bay. It controls body temperature and, through its
network of sensory nerve endings, it transmits information about external
stimuli to the brain. Thus it enables us to feel things, to experience
painful and pleasant sensations and enjoy physical relations with others.
THE SKIN'S STRUCTURE
The skin is made up of two main parts. The outermost layer - the epidermis -
is made up of several layers of cells. On the surface are flattened,
overlapping horny cells which are forever being shed as a material called
keratin which is just visible as tiny scales.
Dead cells are continually being replaced from below and it takes about
three weeks for a new skin cell, formed in the underlying dermis, to dry
out, die and be shed. The epidermis is protected by a naturally acid mantle
which deters bacteria and pollutants.
The epidermis is firmly attached to an underlying layer called the dermis.
Tiny, finger-like bulges from the dermis fit into sockets in the epidermis
and this waviness at the junction of the two layers of skin gives rise to
ridges which are most obvious at the fingertips.
The dermis is madeup of bundles of protein fibres, called collagen, and
elastic fibres. Embedded in it are the sebaceous oil glands, sweat glands,
hair follicles, blood vessels, pigmentation cells and the living skin cells.
This is the working level of the skin where all the essential functions and
processes are carried out and the blood vessels supply oxygen, protein,
vitamins and minerals. The sweat glands are essential in regulating the
body's temperature, while the sebaceous glands lubricate the skin and hair.
The apocrine glands develop at puberty and are a sexual characteristic. The
cells that produce pigment, melanocytes, determine skin colour and can cause
There is a fine network of nerve endings in both layers of the skin and
they are particularly numerous at the fingertips. They transmit pleasurable
sensations of warmth and touch, as well as the less agreeable feelings of
cold, itching and pain.
WHAT CAUSES SKIN COLOUR?
Skin colour is due to the black pigment melanin which is produced by pigment
cells in the lowest layer of the epidermis. There is the same number of
pigment-producing cells in the skin of all people but the amount of melanin
varies. In dark-skinned people there is more melanin than in light-skinned
people. Freckles are caused by the pigment cells' uneven production of
melanin, which can be exacerbated by exposure to the sun's rays.
WHITE WITH FEAR
Other factors contributing to skin colour are the blood in the blood vessels
of the skin and the natural yellowish tinge of skin tissue. The state of the
blood within the blood vessels can dramatically change skin colour. For
instance, we become 'white' with fear when small blood vessels close off,
'red' with anger due to an increased blood flow and 'blue' with cold when
most of the blood moves out to the tissues as the blood flow slows down.