What are the hairlike projections on cells called?

The hairlike projections on cells are referred to as cilia. These structures are typically short and numerous and extend out from the surface of many types of cells, serving critical functions related to movement and sensory reception. Cilia can help in the movement of fluid or the clearing of airways in the respiratory tract, as they can beat in coordinated waves. This is essential for maintaining clear passages in the lungs and for various other cellular processes.

Flagella, which are longer and typically fewer in number compared to cilia, also serve the purpose of movement but are found mainly on sperm cells and certain microorganisms. Pseudopodia are temporary extensions of the cell membrane used for movement and feeding in certain cells, particularly amoebas, allowing them to flow and engulf food particles. Microvilli, on the other hand, are smaller extensions that increase the surface area of cells for absorption, commonly found in the lining of the intestine. Each of these structures has distinct functions and forms, making cilia specifically recognizable for their role as hairlike projections on various types of cells.