Skin...Our Personal Bodyguard

Man enjoying the cooling benefits of sweat

Skin is pretty amazing. It is your largest organ and protects you from the outside environment. The skin is designed to protect you from mechanical, chemical and biological damage. The parts that make up the skin are perfectly suited to their jobs. First, the skin is made up of three layers: the Epidermis (outer layer), Dermis (middle layer), and Hypodermis (deepest layer). The Hypodermis isn't actually part of the skin, it just anchors it to the underlying organs, but for now we'll just include it. The outermost layer, the epidermis has an outermost layer of dead cells, so they can be sloughed off without damage to the underlying  layers. Pretty cool right? And even if the damage is deeper than the epidermis and enters the dermis, it's all good. The dermis is made of dense connective tissue, and strong substance designed to protect the organs underneath. Not only does the skin have these three layers, it also has hair and ducts that secrete substances that protect us. The hair increases the sensitivity of the skin, and allows tissue to regenerate in the hair follicles, where it wouldn't be able to regenerate somewhere else. Sebum and sweat are the substances secreted by the skin to protect it. Sebum keeps our skin and hair hydrated and creates an acid barrier that protects us from chemical and biological factors, like bacteria. The skin also regulates the temperature of our body. There are several ways for our body to cool down, including sweating and vasodilation (expansion of vessels). This expansion brings the blood closer to the surface, allowing heat to escape. Vasoconstriction (contraction of vessels) brings blood away from the surface preventing heat loss. Vasocontstriction, along with goosebumps keep the body warm and cozy. Another function of the skin is to protect the body from UV radiation. The skin has these things called melanocytes that produce melanin, which is partly responsible for skin color. Increased exposure to the sun generates more melanin, which darkens the color of the skin (a tan). The darker color actually acts as a barrier to block out some UV rays. So the skin will actually change to protect itself from harmful radiation. Skin is pretty amazing; I don't know what we would do without its protection.

Sweating Man Image From http://en.wikipedia.org/wiki/Perspiration