Your Skin!

Your skin is the ultimate vessel for the human body; it receives and transports, accepts and expels according to the body?s
needs. It is container, defender, regulator, breather, feeler, and adaptor. But success in these roles is not accomplished
automatically. As sturdy as it is, the skin requires attention and maintenance to function properly. Without such care, the
complex organization of the skin breaks down, making it and the body it protects susceptible to injury and disease. Thus, the
body's coverall organ is as fragile as it is seemingly unyielding.

The skin is the largest organ of the body and is as indispensable as the body's other major organs. But the skin is perhaps
the organ that brings us closest to an understanding of organ function, because its anatomy and function can be partially
observed by the naked eye. In addition to its ability to communicate internal physiological information, like the presence of
fever, the skin also reacts to external stimuli, like sun exposure, toxins, and even psychological stimuli. From poison
indication and warning, to the "cold sweats" and "goosebumps," the skin is a constant and dynamic interface between the body
and its environment.

Skin is made up of two primary layers that differ in function, thickness, and strength. From outside to inside, they are the epidermis and its sublayers, and the dermis, after which is found subcutaneous tissue, or the hypodermis. The two layers are further differentiated by their respective amounts of hair follicle, pigmentation, cell formation, gland makeup, and blood supply. Moreover, these layers are present in the two general types of skin, thin and hairy, and thick and hairless. The former is more prevalent on the body, while the latter is found on parts of the body that are used heavily and experience extreme friction, like the palm and the heel.

skin is an organ that forms a protective barrier against germs (and other organisms) and keeps the inside of your body inside your body, and keeps what's outside of your body outside. Skin also helps maintain a constant body temperature. Human skin is only about 0.07 inches (2 mm) thick.
Skin is made up of two layers that cover a third fatty layer. The outer layer is called the epidermis; it is a tough protective layer that contains melanin (which protects against the rays of the sun and gives the skin its color). The second layer (located under the epidermis) is called the dermis; it contains nerve endings, sweat glands, oil glands, and hair follicles. Under these two skin layers is a fatty layer of subcutaneous tissue (the word subcutaneous means "under the skin").

On average, an adult has from 18-20 square feet (about 2 square meters) of skin, which weighs about 6 pounds (2.7 kg).

Epidermis
The epidermis, the outermost layer of skin, is thin but complex. Melanin, which is responsible for skin pigmentation, is found throughout the epidermis. The epidermis also keratinizes (described below) to produce nails, hair, sweat, and to regenerate. It is the foremost initiator of cell death and regeneration, the final boundary between body and environment. It is useful, however, to itemize the epidermis layer and its progressive keratinization from its innermost sublayer to its outermost, because cell growth naturally follows this pattern.

Dermis
The second, larger layer of skin is called the dermis. Its main roles are to regulate temperature and to supply the epidermis with nutrient-saturated blood. The dermis is made up of fibroblasts, which produce collagen connective tissues and which lend elasticity and support to the skin. It is the seat of hair follicles, nerve endings, and pressure receptors. Furthermore, the dermis defends the body against infectious invaders that can pass through the thin epidermis, the first defense against disease