What are the small hair-like structures found on the surface of some cells called?

The small hair-like structures found on the surface of some cells are called cilia. These structures are typically short and numerous, providing the ability for certain cells to move or for substances to move along the surface of the tissue. Cilia play vital roles in various organisms, such as helping to propel mucus in the respiratory tract or aiding in the movement of eggs in the female reproductive system.

Understanding the function and structure of cilia is essential in grasping how cells interact with their environment and how they contribute to the overall function of tissues and organs. In contrast, flagella are longer and usually singular, serving a different purpose, primarily in the movement of individual cells, such as sperm. Filaments could refer to various types of cellular structures but do not specifically denote hair-like structures, and microvilli, while also relating to cell structures, are distinct from cilia, being smaller and non-motile, primarily involved in increasing surface area for absorption rather than propulsion. Thus, cilia are uniquely suited for their roles due to their specific characteristics and functions.