Which membrane secretes mucus and lines parts of the body that are open to the outside?

• A. Serous membrane
• B. Mucous membrane
• C. Synovial membrane
• D. Cutaneous membrane

Answer: (B)

Mucous membranes line cavities and passages that open to the outside and secrete mucus. This mucus, produced by goblet cells in the epithelium, moistens and protects the surfaces of the digestive, respiratory, urinary, and reproductive tracts and helps trap debris and microbes. The membrane is known as mucosa (mucous membrane) and sits over a layer of connective tissue called the lamina propria. By contrast, serous membranes line closed body cavities and secrete a watery serous fluid to reduce friction; synovial membranes line joints and secrete synovial fluid; and the cutaneous membrane is the skin. So the membrane that fits the description is the mucous membrane.