The biggest organ

Valsala R gives a lowdown on human skin and its many functions

Snakes moult. We all know that, don’t we? But did you know that we moult too? Not as dramatically, thankfully! (Can you imagine seeing a large patch of human skin lying around in the corner of your living room?!) But we shed our ‘dead’ skin and have completely new skin every month. We apparently shed 30 to 40,000 cells every minute and some sources say that more than half the dust in our homes is actually dead skin! Ugh!

So, considering that we pay quite a lot of attention cosmetically — on average we spend about Rs 1,500 on skincare every month although at the upper end it’s more like 10 times that — is it really worth all that?

The skin is our largest organ. On average, it covers an area of 2 square metres and accounts for 15% of your body weight. Why do we carry all this around? Well, we have neither feathers nor much body hair to protect us from the elements so the skin has to do all that work apart from everything else. It protects us from heat and cold; and from injury and infection. Don’t put it to the test though — stomach acid would burn right through (that’s how hard our body works to digest all the junk we put into it!).

Bacteria is prevented from getting in and water from getting out by this important organ. However, when you think of an organ, we think of it as ‘doing’ something rather than just acting as a barrier, don’t you? The skin has a more active role as a sensory organ and also in the making of vitamin D.

The outer layer of the skin is thin and is called the epidermis. The epidermis contains melanocytes which produce melanin and which in turn give the skin its colour. Though most of us have the same number of melanocytes, they don’t all produce the same amount of melanin and hence the colour differences. Melanin protects us from the harmful effects of the UV rays from the sun — those of us who don’t have enough of it must add sunblock to our skin care bill. 

The second layer of the skin is called the dermis. This contains blood vessels, lymph vessels, hair follicles, sweat glands, collagen, fibroblasts, nerves and sebaceous glands. The blood and lymph vessels carry nutrients around, also hormones and antibodies besides removing waste. Collagen holds tissue together and gives us a plump, healthy look and nerves tell your brain what’s happening. Some of the nerves are connected to muscles instead of the brain, sending signals to react more quickly to heat, pain, and so on.

Although all of these are important functions, they are not peculiar to the skin alone. Hair follicles and sweat glands are. We have about 5 million hair follicles when we’re born with about 1 million of them on our heads. The hair follicle is one of those rare structures in our bodies that can stop functioning and then start all over again. And so, we spend crazy money to encourage them to get to work when we lose hair.

Do we really want or need to sweat? ‘No’ to the want but an emphatic ‘yes’ to the need. Sweating regulates body temperature. It helps the body cool down when you’re all hot and bothered whether physically or mentally.

Below the dermis lies the third layer of the skin — the subcutaneous fat layer. This layer is a sort of shock absorber that protects the body from injury. It consists of collagen for elasticity and fat cells for energy. Yes, fats are energy efficient and the human body keeps a good stock of it to supply our specially energy-consuming brains. Baby fat isn’t just a term. Babies need the fat to develop their brains that may be vulnerable to a shortfall of energy.

Of course, the skin changes its texture and composition depending on the need. It’s thicker on the soles and palms, for example. And the hair follicles don’t even exist there! How marvellous is that!

The skin is often a good indicator of your general health. If it has a good balance of oil and moisture, an even texture, good elasticity, and is blemish free, you’re healthy (or still young!) About 1000 species of bacteria have taken up residence on your skin. Some good, some not so good. Should you bathe every day? Ah! That is the question.