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Your skin is the largest organ of your body and accounts, on average, for 16 percent of your bodyweight. It is the first line of defence you have against viruses and bacteria, but cannot protect against insults, the tax man or your mother-in-law, despite how thick it may be.
The skin does all sorts of wonderful things – it regulates your body temperature, it protects your body tissue, it changes colour in the sun, it varies in thickness according to localised need (think of the difference between the skin on your eyelids and your skin soles), it repairs itself every 28 days, and it shows you very quickly when you are allergic to something – hives and bumps or rashes appear on the skin. It glows when you are healthy and takes on a sallow colour when you are not. It can repair itself in a few days from cuts and bruises.
Skin composition
The skin consists of three major components – the hypodermis, the dermis and the epidermis.
The hypodermis is the deepest section of the skin and it refers to the fatty tissue below the dermis that insulates and pads the skin.
The dermis, which lies between the other two layers, provides structure and resilience to the skin. The dermis is usually about 2 mm thick and contains structural proteins, blood and lymph vessels, mast cells and fibroblasts. This level of skin plays an important role in keeping you hydrated. The blood vessels in this layer of skin constrict or dilate to regulate the body’s temperature.
The epidermis consists of five layers, which are all in all not thicker than 0,1 mm. The epidermis acts like a protective shield to the body. The dermis and epidermis contain sebaceous glands, sweat glands, pores and hair.
There are many diseases that can affect the skin – just think of the nasty acne breakout you get before a big date. The skin is very sensitive to stress and allergies and diseases like psoriasis, eczema and urticaria are fairly common.
The skin is a busy part of your body. In one square centimeter on the back of your hand, there are almost three metres of blood vessels, 30 hair follicles, 300 sweat glands, 600 pain sensors, 6 cold sensors, 36 heat sensors 75 pressure sensors, 9000 nerve endings and more than ten metres of nerve endings and four oil glands.
Interesting facts
- The average person sheds about 18 kilograms of skin in a lifetime.
- Skin thickness varies from 0,5 millimetre on your sex organs to about 6 millimetres on the soles of your feet.
- The skin cannot absorb water or solutions with sugar or salt. It can absorb a limited amount of oils and fats.
- Skin produces its own antiseptics and prevents harmful bacteria from entering your body.
- About 10 percent of your blood circulates through your skin.
- Approximately 60 percent of the human body consists of water. Skin prevents that water from evaporating.
- Your skin has more nerve endings than any other part of your body.
- Skin cancer is the most common form of cancer among South Africans, with one in 167 South African men and one in 213 women developing melanomas every hour.
- A single bad case of sunburn during childhood can double the risk of skin cancer later in life.
- Regular application of suscreen with an SPF of at least 15 during the first 18 years of life can significantly lower the risk of some types of skin cancer by more than 75 percent.
- Sun beds and tanning lamps emit UV A rays and are unsafe, even though advertisements may claim the contrary.
(Health24, February 2006)
