When we refer to the sun and to tanning, we refer to melanin. Melanin is produced when the sun touches the skin, making us go brown. This pigment darkens the skin to protect it from the damage caused by ultraviolet (UV) rays. Our hair and the iris of the eye also contain melanin. But what exactly is melanin and what is it for?
Melanin is not unique to humans, but is to be found in most living things. Thanks to melanin, some animals can change their colour as camouflage and plants have different colours. The melanin pigment is derived from tyrosine, an amino acid essential for our body to function properly. Melanin is made in the melanocytes (epidermal cells) and also in the hair follicles. It’s a bit like a coloured crayon, responsible for brownish and reddish tones in the skin and hair. But its main function is, in fact, to protect us against the damaging effects of UV radiation. Read More
Manufacturers promise flawless skin if we use cosmetics that they claim penetrate the skin and improve cell functioning. And yes, of course they do penetrate – but to what depth? The skin’s outermost layer, specially designed to act as a barrier, is formed of nearly impermeable tissue. So, how can cosmetics penetrate the skin?
No cosmetic active ingredient has yet been invented that crosses the epidermal barrier and penetrates deep into the skin. In fact, a substance that appears to penetrate the dermis and hypodermis is most likely absorbed by the blood vessels. In that case it would be a drug, not a cosmetic active ingredient, because it affects metabolism. With nicotine patches applied to the skin, for instance, tiny nicotine molecules travel via the skin layers until they reach blood vessels. Does nicotine act on the skin on its way to the blood? The answer is no. Read More
Our skin is equipped with the perfect machinery whose function is to retain water and prevent dehydration. The skin, a vital organ in our body, has the crucial function of protecting all the other organs within it. And it does so through a complex network of molecules called the natural moisturizing factor (NMF), which ensures a delicately balanced epidermis, despite environmental variations in humidity and temperature.
When we are born our skin is already equipped to stay hydrated and protected from UV rays. Time and environmental aggressions wear down the skin’s mantle, with the result that we lose the water-retaining capacity in some of the beneficial substances in the skin, which should contain some 10% to 15% water. If the water level falls to under 10%, dry skin problems develop: the skin becomes brittle, rough and dull and is more prone to eczema and infections. How can we ensure that the skin retains a minimum of water? Read More
It seems to be a simple notion, yet is deceptively so. Since our skin has no receptors to alert us to dampness, how can we know we’re touching a wet surface? How do we know that the rain has soaked our clothes? In fact, we infer rather than feel wetness: our brain remembers wetness because of a combination of stimuli recorded in memory.
The mystery is this: the skin lacks specific receptors for the sensation of wetness, yet we sense dampness when we touch something wet. Researchers at the University of Loughborough (UK) report that the perception of wetness comes from our ability to feel cold and tactile sensations such as pressure and texture. This combination of stimuli is, in short, what tells us that we are touching something wet. Read More