The Integumentary System, Part 1 - Skin Deep: Crash Course Anatomy & Physiology #6

When you hear about your “organs,” you probably think of your heart, or your liver, or your lungs. Maybe you picture Captain Nemo playing the organ aboard the Nautilus. Why do they have an organ on a submarine? That is - that doesn’t make any sense. But your first associations with that term probably overlook your biggest organ.

I’m talking about your skin. The glorious fleshy shroud that keeps the world out, and you in. Your skin protects your body against infection and extreme temperatures, maintains your balance of fluids, and even synthesizes vitamin D for your own personal use. Its many nerve endings allow you to sense the outside world, and its sweat glands and

blood vessels help you maintain a proper temperature and communicate a whole range of stuff -- from your health to your emotions -- through things like blushing, and flushing, and sweating. It also accounts for about 3 to 5 kilograms of your body weight, and if you could spread it out, it would measure up to two square meters, enough to cover your bed -- the most

disgusting, paper-towel-thin, waterproof, insulating, stretchy, self-repairing, lifetime-lasting quilt on the planet! It comes in lots of different colors, you can cover it up, or show it off, or tattoo the periodic table on it if you want. And of course, without it, you would basically shrivel up and die in no time. Together with your hair, nails, and sweat and oil glands, your skin forms your integumentary system.

And if you’ve ever been burned, or had surgery, or stepped on a nail, you know how fast complications arise when it gets damaged. But it also heals up quite quickly.

LAYERS. Like an everlasting gobstopper, the key to your integumentary system is layers. And although you can’t tell by looking at it, your skin actually has three of them, each with particular types of cells that have their own skin jobs, to borrow a phrase from Blade Runner or BSG… whichever you like! The epidermis is the only layer you can actually see, assuming that your skin is intact, which is