Skin and homeostasis work together to help the body maintain a constant internal environment. The relationship between them consists of three parts: a receptor, a control center and an effector. Human skin contains receptor cells that sense a change in the environment. These receptors send information to the control center, the hypothalamus in the brain. The hypothalamus then tells an effector, such as sweat glands or blood vessels in the skin, to react in order to maintain a stable body temperature.
During temperature homeostasis, or thermoregulation, the skin and homeostasis cause the body to sweat. When the skin senses that the body is heating up because of the environment's temperature, the hypothalamus sends a signal via nerves to sweat glands and blood vessels in the skin. The blood vessels dilate to allow more blood flow through the skin, which — in tandem with sweating — lowers body heat.
Body temperature regulation done by skin and homeostasis also informs the hypothalamus of when the body is cold. This causes the hypothalamus to send signals to the body to tell it to raise its temperature. The body then begins shivering, constricting blood vessels and forming goosebumps in a process called piloerection. Piloerection is when hair follicles make the hair stand up in an effort to warm the body.
The human body contains many types of cells. The cells that make up the body's nervous system work together along with the skin and homeostasis to regulate the body. Specialized cells of the skin make up three different layers: the epidermis, the dermis and the subcutaneous.
The epidermis is the top-most layer of skin that protects the body by preventing water loss and invasion of viruses and microorganisms. Stem cells located in the epidermis maintain the skin by producing new skin cells. These new cells are made to replace lost cells that are naturally shed by the skin and when healing an injury. The skin's top layer also contains melanocytes, which are specialized skin cells that produce melanin — a pigment that protects the body from the ultraviolet radiation made by the sun.
The dermis contains sweat glands, oil glands and hair follicles. The subcutaneous layer, or bottom layer, of the skin is made up of connective tissue, fat cells, nerve cells, veins and arteries. It is the sweat glands, hair follicles and veins in the dermis and subcutaneous layers that are manipulated when the relationship between skin and homeostasis is doing what it should.