In which direction do cilia in the respiratory system move?

The movement of cilia in the respiratory system is critical for maintaining airway hygiene and protecting the lungs from pathogens and debris. Cilia are tiny, hair-like structures that line the respiratory tract. They beat in a coordinated, wave-like motion that primarily moves mucus and trapped particles upward toward the throat. This sweeping action is essential for the mucociliary escalator mechanism, which helps clear mucus away from the lungs and prevents infection by moving contaminants out of the airways, allowing them to be swallowed or expelled.

While cilia do exhibit some movement in other directions, their primary and most significant role is in moving materials upward towards the pharynx. This action ensures that harmful substances are kept out of the lower respiratory tract, thereby playing an essential role in respiratory health.