Smooth muscle and cartilage are two of the tissues present in the walls of structures in the mammalian gas exchange system. Complete Fig. 5.1 to indicate how these tissues are distributed in the gas exchange system of mammals. Select from the four structures listed below: alveolus, trachea, bronchus, bronchiole.
Outline how tobacco smoke can bring about lung cancer.
Fig. 5.2 shows a section through the wall of one part of the gas exchange system in a person with COPD. The tissue in the wall section labelled X is the outcome of changes to the original healthy tissue that lines the lumen of the gas exchange system. The tissue shown is not scar tissue and is not a tumour. The area labelled X on Fig. 5.2 looks different from the original healthy tissue in the same part of the gas exchange system. Describe these differences.