How Does Skin Work?
The skin is the largest organ of the human body and is the only organ that is not internal. It acts as a protective layer for the rest of the body, keeping out bacteria, viruses, allergens, fungi, and other potentially harmful substances. Along with the skeletal and muscular systems, it helps to hold the other organs in place.
Other responsibilities of the skin include:
- Synthesizing vitamin D from the sun
- Working to support the nervous system in sensing touch, pain, temperature, and pressure
- Regulating temperature
- Provides protection from the sun and weather elements
- Working with the lymphatic system to eliminate fluid waste
Without skin, the rest of the body would literally evaporate.
The skin of an average adult weighs between 10-20 pounds and is made up of three layers. The epidermis, the dermis and the subcutis.
The epidermis is the outermost layer of skin and consists of cells called keratinocytes. These cells continuously form new layers of skin that slowly grow outwards as the top layer dies and flakes off. The entire epidermis layer of your skin is replaced every five weeks or so. The epidermis also houses defensive cells called Langerhans cells, which are responsible for alerting the immune system if any infectious viruses or bacteria are detected.
Dermis is the second layer of skin and is made up mostly of collagen and elastin, which give the skin firmness and strength. It connects to blood vessels which deliver oxygen and vital nutrients to the skin cells as well as help to regulate body temperature. When heat is sensed, the blood vessels signal for an increase of blood flow to allow heat to escape the body. When cold is sensed, they slow down blood flow so as to conserve heat.
The dermis is home for the network of nerve fibers and receptors that respond to touch, pressure, and pain. These nerves send all important signals back to the brain. Another important thing the dermis helps support is the hair follicles, glands, and sweat ducts. These also help to regulate body temperature and are part of the lymphatic system which removes waste from the body.
The subcutis is the deepest layer of skin. It holds a layer of fat which acts as food storage for the body in case of calorie shortage. This layer of skin and fat also acts as insulation for the body and helps to cushion the muscles and inner organs from falling and bumping into things.
Why There Are Different Skin Colors
People around the world have different skin colors because of a pigment called melanin. Melanin is produced by the epidermis as a means of protection from the sun’s ultraviolet (UV) rays. Ethnicities that comes from tropical regions where the sun’s UV rays are the strongest have the darkest colored skin. Ethnicities that come from northern countries where the solar rays are weaker developed white, fair skin.
Interesting fact: Australia has the highest rates of skin cancer. It is also the country that has the highest population of northern European people. It is believed this is due to their fair skin color and the harsh, hot environment of Australia complete with strong UV rays that their ancestors did not have to deal with.
Common Skin Problems
Here are the most common skin-related disorders:
- Acne: Small red bump caused by infected hair follicles, pus-filled bumps, solid nodules, or cysts below the skin.
- Cold Sore: Fluid-filled blisters that appear on or near the mouth.
- Canker Sore: A painful, open mouth ulcer.
- Psoriasis: Thick patches of red, dry skin. Generally occur around the torso, limbs, scalp and face.
- Rosacea: Flushing, redness, broken blood vessels that result in breakouts and oily skin. May also affect the eyes.
- Eczema: Extremely dry, itchy skin that may appear irritated and inflamed.
- Hives: Itchy, raised red bumps that appear on the skin as part of an allergic reaction to something.
- Skin Cancer: Cancer of the skin. May cause irregular coloring on the skin.
- Lupus: Disc-shaped rash that appears on the skin, accompanied by fever, headaches and swollen joints.
- Rubeola (Measles): A viral infection that causes tiny red spots with blue-white centers inside the mouth and a rash over the entire body.
- Vitiligo: Loss of pigment in the skin.
- Warts: Rough, grainy bumps on the skin that are pink, brown or yellow.
- Cellulitis: When bacteria enters through a break in the skin (a scratch, crack or cut) and creates a small infection. Appears red and swollen and may hurt to touch.
- Impetigo: Most commonly seen in children. An itchy rash with fluid-filled blisters and swollen lymph nodes.
- Shingles: Thick red patches with fluid-filled blisters, accompanied by rash that wraps around the abdomen and spine.
For more information about various skin conditions and their treatments, please see the articles above.