Galen Anatomy and Physiology (A&P) 1 Theory Exam 2 Practice 2026 - Free A&P Practice Questions and Study Guide

Membranes are grouped by where they line and what they secrete. Mucous membranes line cavities that open to the exterior of the body, such as the mouth, nose, digestive tract, and parts of the urinary and reproductive tracts. They secrete mucus to protect surfaces, trap pathogens, and keep things moist. Serous membranes line internal, closed cavities like the chest and abdomen (pleural, pericardial, and peritoneal spaces) and produce serous fluid to reduce friction as organs move. Cutaneous membrane is the skin, and synovial membranes line joint cavities. So, for membranes found in body cavities close to the exterior, mucous membranes fit that description best.