Organization of the Integumentary SystemThe major organs of the integumentary system are technically referred to as membranes. We tend to think of organs as discrete entities within the body, but remember that, by definition, organs simply consist of at least two tissue types functioning together towards a common purpose. Looked at this way, the skin, perhaps the most important of these membranes, certainly qualifies as an organ. All of the membranes of the integumentary system line body surfaces or internal cavities, and three major types can be identified and described.
- Serous Membranes: Serous membranes are organs that line internal body cavities which lack any connection with the outside environment, and often surround and line other internal organs. They typically have a simple structure, consisting of a single layer of epithelial tissue attached to a thin layer of loose connective tissue. Examples of serous membranes would be the membranes lining the thoracic and abdominal cavities.
- Mucous Membranes: Mucous membranes, to which we have referred previously, are organs which line internal body cavities that are continuous with the external environment. This includes the inner surfaces of all organs of the digestive tract, the respiratory system, and the urinary and reproductive systems. Like serous membranes, mucous membranes are composed of a combination of epithelial and connective tissues. Mucous membranes get their name from the fact that the cells of these organs secrete mucus, a substance that serves to lubricate the surface of the membrane and protect the organism from infection.
- The Cutaneous Membrane: The cutaneous membrane lines the external surfaces of the body and is also the technical term for the skin. Since the skin is the most complex and versatile organ of the integumentary system, we will explore it in more detail.