This is an I-Heart podcast.

Guaranteed Human.

Welcome to Brainstuff, a production of IHeart Radio.

Hey, Brainstuff, Lauren Vogelbaum here.

If you've ever watched a medieval era drama or fantasy,

you may have marveled at the elaborate armor the characters wear into battle.

Made of plates or scales or male, armor is built to protect the wearer from specific types of

weapons and attacks. It may not feel like it, but your skin is also a type of incredibly effective armor, built to fend off specific attacks.

It's not great at handling swords or arrows, but to be fair, those are relatively new inventions.

Far older threats, like microbes and ultraviolet light. That's where our skin is a hero.

It's our first line of defense as we move through the world, though it operates more like

the manned walls of a castle than armor on a night. Specialized cells and surrounding structures

form a physical barrier between you and everything that's not you, sort of like a castle wall.

And inside of that, an immune barrier stands at the ready, like a castle's guard, to eliminate any threats that do make it through.

But for our body's most visible organ, all of this happens on a microscopic level.

So today, let's delve into the skin barrier, how it protects us, and what can happen when

something goes wrong. We've talked before on the show about the layers of the skin. The innermost

layer, the hypodermis, provides structural

support. It contains fat to insulate and cushion our underlying muscles and organs, plus

blood vessels to get supplies to the middle layer, the dermis. The dermis contains all of the

skin's equipment, nerve endings, sweat glands, pear follicles, and so on. All of that is sealed

in and protected by the outermost layer, the epidermis. The epidermis itself has two main layers,

...