Final answer:
Epithelia exhibit polarity, with an apical surface that is free or facing the body's exterior or internal organ cavity, and a basal surface that is attached to the underlying tissue through the basal lamina and basement membrane.
Step-by-step explanation:
All epithelia exhibit polarity, which is defined by the presence of an apical, or free, surface and a basal, or attached, surface that differ in both structure and function. The apical surface faces the body's exterior or the cavity of an internal organ and may feature structures such as cilia or microvilli.
The basal surface is attached to the basal lamina, a part of the basement membrane, which separates the epithelium from the underlying connective tissue. Epithelial tissues are involved in protections, absorption, filtration, excretion, and secretion, with specific specializations depending on the location within the body and the function of the tissue.