70. Skin! What’s It Good For, Anyway?

Your skin is the largest organ of your body, covering approximately 20 square feet of space on the average adult body. Skin comprises two main layers known as the epidermis, the layer we see, and the dermis directly underneath the epidermis where collagen and elastin are contained. Deeper still, the subcutaneous layer of skin exists to provide support to the dermis in the form of fatty tissue. In this article, we’ll explore the four main functions of skin – what they are and why we need them.

Protection

Probably the most important function of the skin is its ability to protect the human body from the elements. Your skin is your first line of defense and provides a physical barrier between your internal organs and your environment. In addition to protecting you from physical harm, your skin also helps hold in necessary fluids and moisture while blocking out unnecessary or harmful ones. This important function allows us to immerse our bodies in water without worry.

Radiation and infection would be much more serious concerns for most people if our skin didn’t provide protection. Melanin in the epidermal layer of our skin helps to provide a shield between body tissue and the harmful UV rays of the sun. Our skin helps protect against infection thanks to a thin, oily coat of moisture that covers the skin and creates a barrier to most foreign substances including viruses, bacteria, or fungi. Langerhans cells are also present in the epidermis and regulate immune response to pathogens.

Thermal Regulation

It’s important to maintain a stable body temperature for overall health and well-being. The average human body temperature is 98.6 degrees Fahrenheit, and skin helps to regulate this temperature through blood vessels and sweat glands located in the dermis. If the body temperature goes too high, sweat glands help to cool the body when the secreted sweat is evaporated on the skin. The body is also able to release heat and lower the temperature through the relaxing of small blood vessels in a process called vasodilation.

What happens when outer temperatures are cold and the body is in danger of losing body heat? The fatty tissue in the subcutaneous layer of the skin works like a layer of insulation, helping to prevent the body from losing too much heat and to minimize the effects of cold temperatures on the body. The dermis works through a process called vasoconstriction to maintain the internal body temperature when small blood vessels contract.

Sensation

Our skin detects sensations in our environment including heat, cold, touch, pressure, and pain. Skin is the organ responsible for our sense of touch having nerve endings in the dermal layer of our skin. Without those nerve endings, we may have more injuries as the nerves are able to detect pain to which we can respond.

When injuries to the skin occur, scarring may result. Scarring can damage or destroy nerve endings, resulting in a diminished sense of touch. Cuts and burns are common injuries known to damage nerve endings present in the skin. While first and second-degree burns don’t usually cause long-term damage, third-degree burns can cause permanent destruction of nerve endings which would inhibit you from feeling the pain of the burn resulting in a more severe injury.

Endocrine Function

Even though it is called a vitamin, vitamin D is actually a hormone that helps keep your endocrine system functioning well by regulating blood calcium concentration while simultaneously impacting the immune system. While vitamin D can be made available to the body through intestinal absorption, it is also made available by photosynthesis in the skin. It is the skin’s natural response to exposure to sunlight. 

While the epidermis is the outermost layer of skin, it is actually composed of five sub-layers. Vitamin D is synthesized in the two lowermost layers of the epidermis called the stratum basale and the stratum spinosum. Current research suggests that as little as ten minutes a day in the sun can produce enough vitamin D for a healthy body. 

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