List and describe the three types of epithelial membranes.

Three types of epithelial membranes:
1) Mucous membranes - mucous membranes exhibit a variety of covering epithelia, i.e., stratified squamous, simple columnar or pseudostratified columnar. These epithelia contain mucous producing cells. Mucous provides a physical barrier to microbes. These membranes line internal spaces of the body that open to the outside.

- Mucous membranes are epithelial membranes that consist of a mucous-forming epithelium that is attached to an underlying areolar connective tissue.  The connective tissue layer is called the lamina propria.  These membranes line the body cavities that open to the outside. The entire digestive tract is lined with mucous membranes. Other examples include the respiratory, excretory, and reproductive tracts.


2) Serous membranes - Serous membranes line body cavities (peritoneum) and surround organs such as the lung (pleura) and heart (pericardium). The fluid produced by these membranes reduces friction between internal organs.   

- Serous membranes line body cavities that do not open directly to the outside, and they cover the organs located in those cavities.
- Serous membranes are covered by a single layer of squamous cells and a thin layer of serous fluid that is secreted by the epithelium. Serous fluid lubricates the membrane and reduces friction and abrasion when organs in the thoracic or abdominopelvic cavity move against each other or the cavity wall. 
- Serous membranes have special names given according to their location. For example, the serous membrane that lines the thoracic cavity and covers the lungs is called pleura.


3) Cutaneous membranes - The cutaneus membrane is the skin. 

- Covered with a stratified squamous epithelium, called the epidermis, which manufactures a tough, waterproof protein called keratin.
- The underlying layer of connective tissue is called the dermis. 
- The dermis contains various nerve endings and  glands manufacturing sweat and oil. 
- The dermis is richly endowed with reticular fiber and collagen.  The surface of the skin is dry.