American Academy of Professional Coders (AAPC) Practice Exam 2025 - Free AAPC Practice Questions and Exam Prep Guide

The main characteristic of the serous membrane is that it compartmentalizes large cavities to hinder the spread of infection. Serous membranes produce a lubricating fluid that reduces friction between organs and helps prevent the spread of infections by creating spaces that contain them. These membranes line certain internal cavities, such as the pleura (around the lungs), pericardium (around the heart), and peritoneum (abdominal cavity), providing essential separation between organs so that, in the event of an infection or disease process, the spread to adjacent organs is minimized.

The other options describe characteristics associated with different types of membranes or functions within the body. For example, lining joint cavities relates to synovial membranes, which are distinct from serous membranes. Covering the interior walls of organs that open to the outside pertains to mucous membranes, which are specifically designed for areas that come into contact with the external environment. Acting as a barrier to bacteria is more commonly associated with the skin or mucosal membranes rather than the role and function of serous membranes. Thus, the ability of the serous membrane to compartmentalize cavities and hinder infection spread is a defining and critical characteristic of its structure and function.