Most often when discussing peripheral tissues, a speaker is referring to tissues in the immune system and the skin or other tissues mucosal in nature that have the potential to be exposed to bacteria and pathogens in the environment. These tissues are referred to as peripheral tissues because they are the tissues situated closest to the outside of the body.
The word "peripheral" can also be used as a means to reference to the specific organ or tissues being examined at the time. Context clues may need to be used to determine specifically what peripheral tissues are being referred to. An example of a specific function of peripheral tissues is melatonin receptors. Melatonin receptors are distributed throughout peripheral tissues and are important in regulating things, such as hair growth, skin pigmentation, heart function, cancer cells, reproductive functions and aging. The peripheral tissues can be affected by peripheral perfusion, particularly in very ill patients. Peripheral perfusion refers to how much blood is being provided to the peripheral tissues. This can be indicative of cardiac failure or cardiac arrest because blood is being sent to vital organs and directed away from the peripheral tissues. This can be determined by the temperature of the skin, particularly in the feet.