Most of us think of our skin like the bag in a bag of peanuts: Little more than a handy container that keeps all the good stuff together in one place. Our skin has a lot more to offer than being the equivalent of a brown paper bag, though. Here’s everything it does, as explained by dermatologist Lisa Chipps.
It’s a Triple Threat
The skin is made up of three layers that work together — like the three musketeers, only with fewer silly hats. The outermost layer, known as the epidermis, is the bruiser of the trio, acting as a waterproof barrier between our internal organs and the outside world. Meanwhile, the dermis, which lies just beneath the epidermis, is the brains, housing all of the skin’s supportive structures. “The dermis is full of collagen, which gives the skin its structure, and it contains blood vessels, hair follicles, sweat glands, oil glands and nerve endings,” Chipps explains (don’t worry, we’ll get to what all these things do later). Lastly, you have the deeper subcutaneous tissue, the comedic relief of the trio, which doesn’t do an awful lot that’s useful besides storing fat.
While the actual thickness of these layers remains fairly constant around the body, there are a few spots that need more or less padding. “The palms and soles are covered in thick epidermis tissue to protect from wear and tear, while the eyelids are made up of thinner tissue,” says Chipps. That’s because the thinner skin allows the eyelids to better regulate how much light actually enters our eyes.
While skin always consists of these three layers, it comes in a few slight variations. For instance, African skin features a particularly thick epidermis, which can provide extra protection against the sun. On the flip side, Asian skin has a relatively thin epidermis that can be especially prone to scarring and other kinds of damage. Caucasian skin, meanwhile, consists of a less compact dermis, which can contribute to making wrinkles more noticeable.
It’s a Germ Zapper
As well as acting as a barrier to keep our insides in, the skin also helps to keep the bad stuff out, as it’s equipped with a whole horde of germ-busting cells. “The skin is full of immune cells called langerhans cells, which are constantly surveying the skin for germs,” Chipps explains. “When they find something trying to enter the body that shouldn’t be, they stimulate the immune system to fight against it.” In other words, they’re the guys that yell, “SOUND THE ALARMS!”
But that’s not all they do: Langerhans cells also act as mediators between the immune system and any type of “good” bacteria making a home of our epidermis — that is, other microbes that keep our skin healthy by fighting off any foreign invaders — to ensure that no friendly fire goes down.
It’s an AC Unit (and a Heater)
Everyone knows the skin cools us down by sweating, which increases the amount of body heat we expel through evaporation. But there are other ways the skin keeps us at a pleasant temperature. “When we’re hot, capillaries — which are tiny blood vessels in the skin — dilate, so blood flows to the surface of our skin, where it’s cooled down by the outside air,” Chipps explains. “This now-cool blood then flows through the rest of the body, bringing down our internal temperature.”
These same capillaries contract when we’re too cold, which prevents our warm blood from losing heat near the surface of the skin. Our skin also signals our body hair to stand up when we’re cold so that they trap heat, and to lay flat when we’re hot, which has the opposite effect.
It Has Feelings
Not those kind of feelings, but rather the sense of touch. Thanks to our skin, touch is the first sense we develop as a fetus. The nervous system depends on nerve cells (aka, touch receptors) embedded in the skin to sense the outside world. “Some detect heat, some detect cold, some detect pressure, some detect itch and some detect pain,” Chipps says. There are two main types of touch receptors: Thermoreceptors, which detect heat and cold, and mechanoreceptors, which detect pressure.
While the thermoreceptor group is fairly self-explanatory, the mechanoreceptor group contains three different sensory receptors. The Pacinian corpuscles are located throughout the body and detect deep pressure — say, a punch to the face. The Meissner’s corpuscles are located in our fingertips, lips, nipples and genitals, and they detect light pressure, like a soft smooch. Lastly, the Merkel’s discs are located in the ridges of our fingertips and detect texture, like sandpaper.
It Helps Prevent Cancer
Several types of cancer — including colon, breast and prostate cancer — have been associated with vitamin D deficiency, which is something your skin can help with: The skin produces vitamin D when it’s exposed to sunlight. This doesn’t mean you should hang out at the beach all day long without applying sunscreen, of course. You only need to expose your skin for around half the time it would normally take to start to burn to produce more than enough vitamin D for one day.
Remember: Your skin does you a whole lot of good in addition to keeping your insides from being just a heaping glob on the floor. The least you can do is rub it down with a little sunscreen every once in awhile.