What is Skin?
Stretching From 16 to 20 Square Feet (1.5-1.9 m2) and comprising 15 to 20 percent of a person’s body weight, skin is the body’s largest organ. This protective covering acts as a barrier against pollution, radiation, the elements, harmful microorganisms, and physical trauma.
But that’s not all it does: Skin locks in the body’s moisture, which keeps inner organs and muscles from drying out. To ensure that the body doesn’t develop vitamin D-deficiency diseases such as rickets, the skin manufactures vitamin D from sunlight. Skin also helps regulate body temperature by sweating to cool things off and conserving heat when the air grows chilly. And, thanks to its many nerve endings, skin is responsible for our sense of touch, which allows us to sense pain, pressure, temperature, and pleasure.
Skin guards against heat loss in an ingenious way: by constricting its blood vessels. This conserves heat-giving energy, which is needed by the vital inner organs.
Taking a closer look at skin
Skin is composed of three layers. The top layer is called the epidermis. It measures less than 1 millimeter in thickness everywhere except on the palms and soles (where it is thicker) and the eyelids and inner elbows (where it is thinner). It is in the epidermis that new skin cells are created and melanin the pigment that gives your skin its unique color - is produced. The dermis is skin’s middle layer. It lies under the epidermis and is where skin’s collagen and elastin fibers are located. These fibers give the skin structure. However, they lose their resilience as we age, causing skin to grow slack and creased. Blood vessels, oil or sebum glands, nerve fibers, hair follicles, and muscle cells are also found in the dermis. Skin’s bottom layer is the subcutis. It acts as a reservoir for water and fat cells, and serves as a cushion between the upper layers of skin and the body’s bones and muscles.