Organ of the Month: The Skin
Did you know?
Hair, nails, and some glands are accesory structures to the integumentary system, the official name for system of the skin. Different proteins, like keratin, are responsible for their shape and texture.3
What is the skin?
Skin keeps our human bodies covered! It holds us together, and conforms to our figures. It is our first line of defense against infections and accidents. It provides us with the sense of touch, and it helps us to regulate our temperature1. Our skin is a symbol of beauty, health, and vitality. Weighing around 20 pounds while covering approximately 20.83 squre feet on the average adult, our skin is our largest organ. Besides acting as our first line of defense against disease and the harsh effects of the environment, the skin is responsible for:
- Preventing the body underneath from drying out.
- Storing fatty tissue to be used as energy for the body.
- Synthesizing vitamin D by the light of the sun.
- Providing sensory input to the brain, such as hot and cold sensations, and pressure.3
Healing Properties of the Skin
When the skin is punctured or otherwise wounded blood vessels from the dermis leak into the affected area. The blood clots, and the outside layer of the clot hardens, forming a scab. A scab is a natural bandage, so that injured tissue may heal from the inside out.3
The Layers of the Skin
The skin is divided into three layers: the epidermis, the dermis, and the hypodermis.
The Epidermis is the top outermost layer of skin, and it protects our bodies from the environment by serving as an avascular (meaning no blood vessels), waterproof barrier.2 Five percent of the epidermis is composed of cellular melanocytes which produce the substance melanin. Melanin is responsible for protecting our skin against the sun's damaging Ultraviolet rays, and also determines the color and tone of our skin.1 While all people are born with the same number of melanocytes, skin color and tone actually depends on how much melanin is produced and where it is distributed. For some people, melanin "congregates in patches on the skin, forming freckles", while others may tan more evenly. Carotene is a skin pigment that gives the skin a yellow hue, and pink skin tones derive rosiness from hemoglobin in the blood.3
Our bodies are constantly shedding dead skin cells, which began their cycle at the bottom of the epidermis, and over the span of 2-4 weeks make their way to the surface. The dead cells are strong, and protect the surface of our bodies for a small amount of time before shedding. In fact, every day the body sheds 500 million cells a day, or 1.5 pounds of dead skin every year. This cycle is healthy and beneficial because it allows our bodies to recover from injuries quickly.
The Dermis lies just below the epidermis, or surface of the skin. It is made up of thick, dense, and irregular connective tissue. It is highly complex, and very alive. Within the dermis there will be capillaries, collagenous and elastic fibers, involuntary muscles, nerve endings, lymph vessels, hair follicles, and both sweat and oil glands.3 All of these structures work together to keep the skin flexible, healthy, and cool. This layer is also responsible for communicating sensory information to the brain.
The hypodermis, also known as the subcutaneous fascia, connects the skin to underlying muscles. It is layer of skin which produces lipocytes (fat cells), which provide protective padding to deeper tissue, as well as insulation to the body for thermal regulation.
When skin has been destroyed by disease processes and injury beyond the scope of natural healing, a skin graft may be necessary to protect the wound from contamination. Grafts may be taken from the patients own body, pig skin, amniotic membranes, and engineered skin substitutes.4
For more information please go to organdonor.gov, where you can learn about what it means to be an organ donor.
The Skin Care Answer Book
1) KidsHealth. Your Skin. Retrieved from http://kidshealth.org
2) WebMD. Skin Problems and Treatments Health Center. Retrieved from http://www.webmd.com
3) Colbert, Bruce J., Jeff Ankey and Karen T. Lee. Anatomy and Physiology For Health Professionals 2nd Edition. Upper Saddle River, New Jersey, 07458: Pearson Education, 2011. Print.
4) Fuller, Joanne Kotcher. 2013. "Surgical Technology Principles and Practices sixth edition." St. Louis, Missouri: Elsevier.