True or false: Epithelial cells serve as a barrier to prevent the non-specific movement of chemicals.

Epithelial cells are indeed fundamental in functioning as a barrier to prevent the non-specific movement of chemicals. They form tightly packed layers that line both the outer surfaces and internal cavities of organs and structures throughout the body. This arrangement is critical because it helps to maintain the integrity of bodily systems, controlling the exchange of substances in and out of tissues.

For example, in the skin, epithelial cells provide a crucial barrier to protect underlying tissues from pathogens, harmful substances, and dehydration. Similarly, in the respiratory system, the epithelial cells not only serve as a barrier but also play roles in filtering and facilitating gas exchange, while still preventing unwanted chemicals from passing through indiscriminately.

The barrier function of epithelial cells is a universal characteristic across various types of epithelial tissues, not limited to specific systems or locations in the body, making the statement true.