12. Which of the following epithelial types is correctly matched with its major function?
Answer: D
Simple columnar epithelium is correctly matched with its major function of secretion or absorption.
Simple columnar epithelium is primarily involved in secretion and absorption, making it the correct match among the options provided. This type of epithelium is often found lining the gastrointestinal tract, where its functions are essential for nutrient absorption and secretion of digestive enzymes.
A) Simple squamous epithelium—secretion or absorption
Simple squamous epithelium is not primarily associated with secretion or absorption; rather, its major functions include diffusion and filtration. This type of epithelium consists of a single layer of flat cells and is typically found in areas where passive transport processes occur, such as the alveoli of the lungs.
B) Stratified squamous epithelium—changes shape when stretched
Stratified squamous epithelium does not change shape when stretched; this description is more applicable to transitional epithelium. Stratified squamous epithelium provides protection against abrasion and is found in areas subject to wear and tear, such as the skin and lining of the mouth.
C) Stratified squamous epithelium—diffusion
Stratified squamous epithelium is not involved in diffusion; this function is characteristic of simple squamous epithelium. The stratified structure of this epithelium serves a protective role, making it unsuitable for diffusion processes.
D) Simple columnar epithelium—secretion or absorption
Simple columnar epithelium is indeed correctly matched with its function of secretion or absorption. This epithelial type is specialized for these functions, particularly in the digestive system, where it aids in the absorption of nutrients and secretion of mucous and enzymes.
Conclusion
The correct match of simple columnar epithelium with its primary functions of secretion or absorption is clearly supported by its anatomical and physiological characteristics. In contrast, the other options either misrepresent the functions of the epithelial types or incorrectly describe their properties, reinforcing that D is the only accurate choice.