1.11 - Clearing the Airways

Cilia and mucus clear the airways

• The trachea and bronchi (the tubes carrying air to the lungs) are lined with ciliated epithelial cells.
• These cells have cilia - tiny hair-like structures - along their upper surface.
• Among them are other cells that produce a sticky substance called mucus.

How they work together

1. The mucus traps small particles of dust and any bacteria breathed in with the air, so they stick to it instead of travelling down into the lungs.
2. The cilia beat back and forth in a steady sweeping motion, moving the mucus (with everything caught in it) up the airways towards the throat.
3. There the mucus is swallowed and passed harmlessly down to the stomach.
4. Working together, the mucus and cilia keep the lungs clear of particles and bacteria in the air.