Structures and functions

• Cartilage- involved in supporting the trachea and bronchi, plays an important role in preventing the lungs from collapsing in the event of pressure drop during exhalation
• Ciliated epithelium – present in bronchi, bronchioles and trachea, involved in moving mucus along to prevent lung infection by moving it towards the throat
• Goblet cells – cells present in the trachea, bronchi and bronchioles involved in mucus secretion to trap bacteria and dust to reduce the risk of infection with the help of lysozyme which digests bacteria
• Smooth muscle – their ability to contract enables them to play a role in constricting the airway, thus controlling its diameter as a result and thus controlling the flow of air to and from alveoli
• Elastic fibres – stretch when we inhale and recoil when we exhale thus controlling the flow of air