Select the one false statement about mucous and serous membranes.
a. The epithelial type is the same in all serous membranes, but there are different epithelial types in different mucous membranes.
b. Serous membranes line closed body cavities, whereas mucous membranes line body cavities open to the outside.
c. Serous membranes always produce serous fluid, and mucous membranes always secrete mucus.
d. Both membranes contain an epithelium plus a layer of loose connective tissue.
The correct answer and explanation is :
The false statement is:
c. Serous membranes always produce serous fluid, and mucous membranes always secrete mucus.
Explanation:
Mucous and serous membranes are two types of body membranes that serve different functions and are located in different parts of the body.
1. Differences in Epithelial Types (Statement A – True)
Serous membranes have a consistent epithelial type—simple squamous epithelium (mesothelium)—which allows for smooth, frictionless movement between organs. However, mucous membranes vary in their epithelial type depending on their location. For example, the respiratory tract has pseudostratified columnar epithelium, the digestive tract has simple columnar epithelium, and the mouth/esophagus has stratified squamous epithelium.
2. Open vs. Closed Body Cavities (Statement B – True)
Serous membranes line closed body cavities (e.g., pleura in the lungs, peritoneum in the abdomen, and pericardium around the heart). Mucous membranes, on the other hand, line body cavities open to the outside (e.g., the respiratory, digestive, and urogenital tracts).
3. Fluid Secretion (Statement C – False)
Serous membranes always produce serous fluid, a watery secretion that reduces friction between organs. However, mucous membranes do not always secrete mucus. While many do (like in the respiratory and digestive tracts), some, like those in the urinary tract, do not produce mucus. Instead, they primarily serve as protective barriers without significant mucus secretion.
4. Tissue Composition (Statement D – True)
Both serous and mucous membranes consist of an epithelium and an underlying loose connective tissue layer (lamina propria in mucous membranes and areolar tissue in serous membranes).
Thus, the false statement is C, as mucous membranes do not always secrete mucus.