The gaseous exchange system in mammals

• Role of Goblet cells?

  Line the airways, secrete mucus - traps microorganisms prevents them from going to alveoli
• Role of Cilia?

  On the surface of cells lining the airways, beat the mucus. Prevents lungs getting infected.
• Role of Smooth muscle in the walls of the trachea, bronchi and bronchioles?

  controls their diameter, relaxed at exercise so less resistence to airflow.
• Role of the rings of the cartilage in the trachea and bronchi?

  provides support

  stops them from collapsing when breathe in and pressure drops
• Role of elastic fibres?

  helps exhaling, they stretch and then recoil to push air out.
• role of squamous epithelial cells


  thin flat cells that line the alveoli to allow for efficient diffusion