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(a)A lung scan reveals cancer of the lung.The colours in the healthy lungindicate normal ventilation. On the leftside, the absence of the normal coloursand the presence of the purple colourindicate a nonfunctioning lung.(b)Smoke descends toward the lungs.(c)Postmortem specimen of a human lungshows a cancerous tumour of theupper lobe as a black and white area.The entire lung is permeated withblack, tarry deposits, suggesting a history of heavy smoking.(a)(b)(c)Simulation—AsthmaBronchial asthmais associated with the inflammation of the bronchioles. In asthma, greatereffort is required to exhale than to inhale. The imbalance between the amount of air enteringthe lungs and the amount of air leaving the lungs must be met by increasing the exertion ofexpiration. In this activity, you will view the events that occur in the lung during an asthmaattack. Why does the imbalance in the amount of air entering and leaving the lungs occur?WEBActivityGObronchial asthmaa respiratorydisorder characterized by reversiblenarrowing of the bronchial passages
296Chapter 9NELcells produce mucus, which is designed to trap foreignparticles. Compare the mucous layers in Figures 8 (a) and(c). Ciliated cells line the bronchioles. Cilia sweep away theFigure 8 (b)shows thebeginning of a cancerous tumour and Figure 8 (c)showshow the tumour advances. Note the location of the tumour andits growth. While the tumour is still walled in by the basalmembrane in Figure 8 (c), it has broken through themembrane in Figure 8 (d). 2520151051currentsmoker1–3 years4–6years7–12years13+yearsnon-smokerquit smokingSmoking StatusRisk of Smokers and NonsmokersDeveloping Lung CancerPersons DevelopingLung Cancer (%)Figure 6When smokers stop smoking, their risk of lung cancerdecreases with time.Figure 7A comparison of the bronchioles and alveoli of a smoker and anonsmoker(a)normal(b)cancer develops(c)cancer advancestumournarrowed bronchiole(d)cancer impairs breathingcancer cellsmucusciliagoblet cellbasal cellFigure 8Development of a tumour in the tissues of the bronchiole wallsCase Study Questions