The Skin’s Anatomy

Did you realize that your skin not only functions as a physical barrier, but it also produces your body’s vitamin D, helping to keep your bones strong? It also serves as a line of defense against harmful things (such as fire) by signaling the brain with sensations of heat and pain. Did you know that your skin helps regulate your body’s temperature and fluids? And of course, you understand that your skin protects you from infection and disease, but did you know that it’s capable of setting off a cascade of immune changes in the entire body? Not to mention that it is fantastically capable of healing itself quickly and entirely after a surgery or injury. Yes, our skin is really, truly an amazing organ!

As you might guess, it isn’t a single layer that does all these things. The skin has three layers, each with its own distinct and specific function. The outermost layer is known as the epidermis. It is comprised of five, unique sub-layers. Each of these plays a unique role in protecting the body from environmental elements. There are two, distinctly different types of cells in the epidermis: keratinocytes and melanocytes.

Keratinocytes are cells that help make the skin waterproof. They also protect our bodies from heat, bacteria and microbes as well as chemical contaminants and irritants. Keratinocytes comprise about 90% of the epidermis.

Melanocytes are specialized cells that produce melanin, which is the pigmentation that gives our skin it’s color. Melanin also has the unique ability to absorb UV radiation which would damage our internal organs and structures. Melanocytes make up roughly 8% of the epidermis.

As mentioned before, there are five different layers of the epidermis. The innermost layer is known as the stratum basale. It is in this layer that new skin cells are formed and then slowly migrate outward to the outermost layer. The stratum spinosum is next, then the stratum granulosum, followed by the stratum lucidum, finally ending with the outermost stratum corneum. The stratum corneum is super important because it is responsible for maintaining the protective outer “film” on our skin known as the acid mantle.

Just beneath the epidermis is the dermis. The dermis is home to our collagen and elastin. These are two components of our skin that give it suppleness, firmness and flexibility. These structures are also responsible for the texture and feel of our skin. We make less of them as we age, which is why we tend to see wrinkles and sagging. The dermis also contains many other important structures. Our pain, touch and temperature receptors can be found in this layer as well as many of the glands that help our skin function: hair follicles, sweat glands and sebaceous glands all have different jobs that are important for our health and appearance. The dermis also contains a dizzying maze of blood vessels that bring much needed oxygen and nutrients to the skin.

The innermost layer is the subcutaneous layer. This layer is comprised of fat cells that are held together by connective tissue. Although we often think of this layer as “bad”, it is vital for our bodies to maintain it. Our subcutaneous layer provides insulation for our internal structures, regulating temperature and providing a layer of protection against trauma. Although today many of us have too much of it, our subcutaneous fat served our ancestors well as a valuable source of energy reserves that were necessary for survival when food became scarce. It is an important contributing factor to the success of our species, even though today, we do all we can to keep it in check or eliminate it all together!

As you can see, there’s a lot more to our skin than meets the eye. It is a dynamic and elegant organ that we simply couldn’t live without!