Anatomy of the skin
Your skin: amazing stuff. Tough, yet sensitive, permeable, yet waterproof. It’s flexible, yet strong, considering that it’s very thin. It houses millions of tiny units that regulate its fluid levels and temperature. It can change colour. It even repairs itself. Its your body’s biggest organ.
There are two types of skin � hairy and glabrous. Glabrous skin occurs on your lips, the soles of your feet and the palms of your hands. Hairy skin is found everywhere else, although the amount of hair produced will vary.
Your skin is your body’s largest, heaviest organ, usually weighing around 4kg. It measures about two square metres � even more if you’re Marlon Brando.
It can vary in thickness from less than a millimetre to about half a centimetre. Without sounding like a biology lesson, your skin can be divided into three layers, the epidermis, the dermis, and the subcutis.
1. The epidemis: You might find it disconcerting that the skin you see is actually a layer of dead cells called the corneal layer. It’s the final stage in a cycle that lasts around 28 days and started below the surface, in the epidermis. The epidermis comprises keratinocytes, which are living epidermal cells, and the corneal layer.
The keratinocytes are pushed upwards toward the surface, where they die and are sloughed off. That’s why exfoliating and shaving helps keep your skin looking young.
The epidermis has a water-resistant component which prevents the skin absorbing water like a sponge.
2. The dermis: The dermis is a busy place, almost like an industrial area. Within it operate an array of devices such as sweat and oil glands and hair follicles, as well as a network of blood vessels and nerve fibres, some supporting tissue, collagen and subcutaneous fat. It’s the elastin and collagen fibres in the dermis which provide the skin with its elasticity. The dermal layer has elastin fibres which are neatly layered and relatively thick � particularly in children and people whose skins haven’t been damaged by the sun.
But in older people this layer becomes thinner and the elastin fibres less organised. This is why older people are more prone to wrinkles and the effects of ageing.
3. The subcutis: This layer consists of fat and blood vessels.
Revision date: June 18, 2011
Last revised: by Janet A. Staessen, MD, PhD