| Describe goblet cells | - they secrete mucus
- the mucus traps microorganisms and dust particles in the inhaled air, stopping them from reaching the alveoli |
| Describe cilia | - beats mucus on the surface of cells lining the airway
- they move mucus upward away from the alveoli towards the throat, where it's swallowed
- this helps prevent lung infections |
| Describe elastic fibres | - they are in the walls of the trachea, bronchi, bronchioles and alveoli
- it helps the process of breathing out
- on breathing in, the lungs inflate and the elastic fibres are stretched
- then, the fibres recoil to help push air out when exhaling |
| Describe smooth muscle | - they are in the walls of the trachea, bronchi and bronchioles allowing their diameter to be controlled
- during exercise they relax, making the tubes wider. This means there's less resistance to airflow |
| Describe cartilage | - in the walls of trachea and bronchi
- provides support
- its strong but flexible as it stops the trachea and bronchi from collapsing when you breathe in and the pressure drops |
