The gas exchange system

HideShow resource information

The gas exchange surface in the lungs is extensive, very thin, well supplied with blood and well ventilated. The trachea and bronchi provide little resistance to the movement of air to and from the alveoli.

1. Describe the gross structure of the human gas exchange system

  • (
  • Air is breathe din through the nose or the mouth and it travels down to the trachea
  • The trachea splits into two, one going into the right lung and the other going into the left lung; these pipes are called the bronchi (singular: bronchus)
  • Each bronchus will then divide into many bronchioles
  • Each of these bronchioles will end in a sac called an alveoli
  • The trachea and bronchi are supported by rings of cartilage to prevent collapse due to the difference in pressure
  • The rings of cartilage also allow some movement e.g. for them to expand
  • There is cilia on the walls that line the trachea that help to move the mucus to the back of the throat to be swallowed

2. Observe and draw plan diagrams of the structure of the walls of the trachea, bronchi, bronchioles and alveoli indicating the distribution of cartilage, ciliated epithelium, goblet cells, smooth muscle, squamous epithelium and blood vessels





  • Cartilage: It is found in the walls of the trachea and bronchi to provide support and prevent them from collapsing when the air pressure in them is low. It also keeps the airways open
    • The cartilage is C-shaped in the trachea
    • (
    • While it is irregular shaped blocks in the bronchi
  • Ciliated epithelium: It is found lined in the walls of the trachea and bronchi and even some bronchioles. It is a single layer of cells which is covered with many extensions called cilia on its outer surface. The cilia are able to move to sweep mucus up to the larynx where it is swallowed when it reaches the top of the trachea, so that pathogens are destroyed by the stomach acid
    • (


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Health, illness and disease resources »