In order to understand acne and other conditions of the skin, it is essential to have a good understanding of skin structure and function. This chapter focuses on basic anatomy and physiology of the skin, and on how genetic factors, bacteria, and biological activity of the skin affect and contribute to acne and oily-problem skin conditions. The skin is an amazing organ that is necessary for life. You cannot live without skin. It performs many vital functions that help many other functions of the body.
It responds to hormones, biochemicals, and signals sent from many other organs and tissues in the body. It is the first line of defense to disease and foreign invaders trying to enter the body. When we think of body organs, we might think about the heart or the liver or the brain. An average size person’s skin weighs about 8 pounds or 15 percent of a person’s body weight, and if you stretched all the skin out from the average person’s body, it would take up about 18 square feet!
The skin is a complicated covering that helps to cushion and protect the rest of the body and internal organs. It has many physiological functions:
- Containing 25 percent of all the blood in the body, the skin regulates body temperature by decreasing blood flow when the environment is cold, and the skin secretes sweat to cool the body through evaporation when exposed to heat. Blood vessels in the skin expand to assist the body in cooling the blood during hot weather. The fat in the subcutaneous layer of the skin helps insulate the internal organs from cold, and it also cushions the bones of the body.
- The skin keeps water from leaving the body, preventing dehydration.
- The skin as the epidermis prevents skin dryness and helps prevent irritation by blocking irritants from entering the skin.
- The skin contains a variety of immune cells that detect, identify, and help defend against foreign invaders, irritants, and pathogenic organisms.
- The skin contains 12 feet of nerves per square inch, and nerve endings that sense cold, heat, pain, and pressure.
- The skin can repair itself when it is injured or torn by generating new cells.
- The skin manufactures melanin skin pigment to protect the body from sunlight.