This article is not medical advice. If you have concerns, please consult your physician or medical professional.
Movie superheroes have flashy, form-fitting outfits with accessible weapons and devices to save the planet, or at least the city. Reflecting cosmic rays, their shields block incoming laser beams and projectiles.
The inventive gear could come in handy for average earthbound people, as we fight off attacks by germs, bites, allergens, cuts and many more intrusions. But we have something even better than a shiny shield. We have skin.
Our largest organ, weighing about 3.5 kilograms, the three layers of skin cover the entire human body to create a delicate but durable defence. It is part of the integumentary system. (The integumentary system includes skin, hair, nails, glands and nerves.) The epidermis, dermis and hypodermis act like a barrier to prevent intrusion from the toxins and germs of the external world. Skin guards the body against wintry weather and rays of summer sun. It sends warning signals to cover up against the cold and heat to ensure a regulated body temperature.
The visible outer skin of humans is called the epidermis. Similar in thickness to a sheet of paper, the epidermis is made of several types of cells — keratinocytes, melanocytes, lymphocytes, Langerhans cells and Merkel cells.
A tight layer of keratinocytes makes up about 90 per cent of the epidermis. A type of structural fibrous protein supplying the surface skin’s structural and barrier functions, keratin also helps to form the tissues of