What is the largest organ in the human body? Some people might guess the liver or maybe even the small intestine. Often overlooked in speculation of seemingly more essential body parts is the skin. All humans and most animals are completely covered by this special organ and rely on it for preservation as well as individuality.

The skin is responsible for protection, sensation, body temperature control, and the synthesis of Vitamin D. At any given point on the human body, the skin is around two millimeters thick. This width allows for the skin to prevent harmful microbes from easily entering the body while also holding all other organs inside. Additionally, the skin enables our sense of touch as it contains a multitude of touch receptors. The touch sensors in the skin can identify coldness, warmth, smoothness, and various other physical attributes. When something comes into contact with the skin, these receptors send signals to the brain which excite a physical response. When receiving a flu shot, for example, the sensory receptors recognize the pinch as the needle goes into the arm and sends messages to the brain, consequently triggering an understanding of discomfort. Equally as important as protection and sensation, the skin holds the ability to regulate body temperature. When body temperature rises above normal levels, the skin begins to perspire. The sweat causes the evaporation of water which results in the cooling effect on the skin’s surface. Blood vessels in the skin, moreover, widen so the blood can be cooled. Conversely, when body temperature drops, the blood vessels in the skin become narrower to help the body retain heat. Some parts of the skin are capable of generating Vitamin D, an essential nutrient that helps to absorb calcium and other minerals. The various complexities of the skin play a large role in the maintenance of homeostasis, a state of internal, physical, and chemical equilibrium.

The skin not only contributes multiple functions to the body but is also inherently elaborate in its structure. The skin has three main layers that each serve a unique function: the epidermis, dermis, and hypodermis. The epidermis is the top-most layer of the skin and acts as the first barrier of protection against dust particles and pathogens. The outermost cells in this layer are constantly replaced by new skin cells as they don’t receive a steady blood supply, therein having to rely on the atmosphere for oxygen. The middle layer, the dermis, is thicker than its counterparts and provides the body with cushioning against outside stress or stain. The dermis contains nerve endings that result in sensation and also blood vessels. The hypodermis is the inner-most layer of the skin and connects muscles and bones with the dermis, thus supplying the skin with blood flow. The intricacies of the skin are pivotal to survival and are greatly beneficial to overall preservation.