Cilia - GCSE Biology Definition

Cilia are tiny, hair-like structures that stick out from the surface of certain cells in the human body and other organisms. They can be found in places like the respiratory tract, where they help to keep the airways clear by moving mucus and trapped dirt away from the lungs. Cilia move in a wave-like motion, and this helps to push things along the cell surface. Apart from cleaning airways, they are also found in various organisms where they help in movement or feeding. In single-celled organisms like paramecia, cilia are used to help them move around in water. Overall, these small structures play a big role in many important processes in living things.