Final answer:
Epithelial tissues are characterized by three cell shapes: squamous (thin and flat), cuboidal (boxy), and columnar (tall and narrow), each with specific functions such as diffusion, absorption, or secretion.
Step-by-step explanation:
The three cell shapes for epithelial tissue are squamous, cuboidal, and columnar. Squamous epithelial cells are flattened and thin, allowing for easy passage of materials through them. This makes them suitable for areas requiring efficient diffusion or filtration, such as the air sacs of lungs and the lining of blood vessels.
Cuboidal epithelial cells are as wide as they are tall, providing better mechanical support and functionality for secretion and absorption, as seen in glandular tissues and kidney tubules. Columnar epithelial cells are taller than they are wide and often feature microvilli, enhancing their absorptive capacity which is beneficial for areas like the small intestine.
These shapes not only define the physical appearance of the cells but also indicate their location and specific functions within the body.