Definition
The mucosa is the innermost layer lining various internal body cavities and surfaces, such as the digestive tract, respiratory tract, and urogenital tract. It is composed of epithelial cells and often includes specialized cells that secrete mucus. This mucus helps to lubricate and protect the underlying tissues, as well as trap pathogens. Think of it as a living shield. The mucosa plays a crucial role in absorption, secretion, and protection.