Today, we get to the surface of things... That's right! Today's subject is the Skin, which includes Nails and Hair.
Skin, Nails, and Hair
Now, it might surprise some of you to see these three things grouped together. Other than being on the surface of us, they don't seem like they have much in common. BEEP! Wrong! All these three things are made of a protein called keratin. And what we see is the dead part of the object. Now we covered some similarities, let's chop down to the more personalized parts.
Skin! We all know it. But did you know that it is an organ? The biggest organ in the body? And it can sure multitask! It keeps our body at a healthy temperature of around 95.8 degrees Farenheit (sp?), keeps water out of our bodies (yep, it's waterproof!), keeps the water we have inside our bodies in, keeps dirt and germs out, keeps all our organs, bones, and stuff inside, allows us to feel, sends the brain messages on what we feel, protection... That's a ton of stuff!
And remember how I said it was big? An adult's skin, when laid out, could cover a bed! And such a big thing is heavy too... an average person's can be over ten pounds heavy! Whoa! And skin can change sizes... when you grow, it grows. When a woman gets pregnant, the tummy-area skin grows over the bump, and then shrinks again. When you gain weight or big muscles, the skin grows.
Skin comes in different colors. Why? It's because of a chemical skin makes call meratin (sp?). It's anti-sunburn protection. Skin may make Vitamin D from sunlight, but too much sunlight causes sunburns or even skin cancer! Part of the skin's natural protection is making this chemical, which darkens the skin. That's how you tan. Some people naturally have darker skin, and therefore, better protection, but they still have to be careful.
Skin is made of layers. The top is called the epidermis, and the next one down is called just the dermis. Then there's a fatty layer which cushions the skin and has a lot of blood vessels and stuff.
The skin has a lot of stuff for its multiple jobs. It grows hair, which is major in temperature control. It has tons of nerve endings, for its touching job. It has blood vessels and muscles (connected to hairs to help with jobs, since they have to stick up to catch and keep warm air [cold weather] and then flatten in warm weather). And there's sweat glands, which release sweat, which cools you down (since evaporation takes heat, and sweat-evaporation takes body heat-energy, which in turns cools us down since it's taking heat away). In other words... a lot of stuff!
Hair grows out of hair follicles. It's almost all over our bodies, and in a variety of sizes from so-tiny-need-magnifying-glass-to-see to the clearly-visible hairs on our heads. There are a few places where there's none... but only a few. Humans have thousands of hair follicles. And the base of different hair types is different per type of hair (for example, curly hair has a kidney-shaped base). Typically, healthy hair is thick and shiny.
Hair follicles are party responsible for zits (pimples)... inside the follicle is a gland that makes and releases subum (sp?), a chemical that's meant for cleaning hair. But when the gland does an overdose job, the follicle's pore is blocked, and nothing can get out. This includes the oil, and bacteria. This in turn makes a swelling (a red bump), which is then called a zit. These overdose jobs happen a lot in the teenage years, when the extra hormones bouncing around tells the gland to make even more of this oil.
Nails! The nail's job is protection from bumping (helps when you stub your toe!). It's also handy for other stuff, like scratching itches, opening envelopes, and prying stickers off surfaces. The Nail is hard, primarily because the top is dead. But there's a living nail base which produces the keratin. Why is this area pink? Because of the blood vessels inside and flowing to the nail base! There's also a flap of skin underneath for protection (the crescent, white part), and a fold of skin helps protect the nail base and root.
Since nail and hair bits that can be seen are dead, that means we can't see them. So it's the only things on our body we cut often. But if we don't, they'll keep growing longer and longer (and nails that grow super-long not only curl up, but look gross!). For some folks, hair and nail keeping are parts of their personalities. There's products for dying and making hair shiny, and coloring nails. Stuff like this has been made and used since Ancient Egyptian days! And millions of hair-and-nail products are sold today! Yikes!
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