Your skin is the largest organ you possess. It's a lot sturdier than it looks, too. Your skin not only protects you from the hazards of the outside world each day, but also literally keeps you from falling apart. This waterproof packaging also insulates you from invading microorganisms, regulates your temperature and removes toxins from your blood. It can even heal itself.
Anatomical Structure
The National Geographic Society says the average human adult supports 8 lbs. of skin, which measures roughly 22 square feet from end-to-end. For each square inch of skin, there are approximately 650 sweat glands. Your entire "body suit" is covered with millions of hair follicles and nerve endings.
According to the University of Maryland Medical Center, or UMMC, skin is made up of three distinct layers called the epidermis, the dermis and the subcutis. The epidermis is the first line of defense from bacterial infection and continuously produces new skin cells to replace dead cells. Melanocytes, which produce the skin pigment melanin, also reside in the epidermis.
The dermis is composed of collagen and houses pain and touch receptors. It also contains a network of lymph glands, blood vessels, sweat glands and hair follicles. After puberty, specialized nodes called apocrine glands release pheromones, which are sex scent hormones that are responsible for the "chemical attraction" between potential mates.
The subcutis, or subcutaneous layer, is the deepest layer of skin and contains fat cells to preserve fuel and to absorb shock from trauma or injury.
Primary Functions
Your skin uses natural sunlight to manufacture vitamin D. However, it also protects you from ultraviolet radiation by secreting more melanin. To protect you from harmful pathogens, Langerhans cells stimulate the immune system to launch a counterattack. Blood vessels and fat cells retain internal heat, while sweat glands lower body temperature and remove cellular waste through perspiration.
Color
Skin adapts to the environment by adjusting the amount of skin pigment produced. People that live in northern latitudes where the sun is not as strong produce less melanin and have lighter complexions. In contrast, those who live in more tropical climates produce more melanin, which results in darker skin.
Touch
Nerves in the skin exist as receptors in one of two forms: those that signal the sense of touch to the brain and those that perceive vibration and pressure. This information is exchanged as physical energy generated from nerves in the skin and delivered as neural energy to the spinal cord and brain. This remarkable feat of mechanical engineering, technically known as transduction, is designed to alert the brain to outside stimulation and stimulate nerves and muscles to respond accordingly.
Wound Healing
When the skin is cut, the epidermis increases the amount of new cell growth at the site. The new cells then surround the site and move laterally across the wound to create a new surface. If the wound is deep, blood pools and clots to form a scab, under which newly formed blood vessels and cells grow to replace the injured tissue.
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