CBSE Class 10 Answered

When a person is exposed to tobacco smoke, his cilia get immobilized and destroyed. As a result, the foreign particles get trapped in mucous and causes microbial infection, which cause excessive growth of cells secreting mucous. As a result, the lining of bronchi swells and produces excess mucous. Sometimes, the alveoli lose their elasticity and break down due to inflammation from the cigarette smoke. The smoker begins to lose his ability to obtain oxygen and dispose of carbon dioxide and other gases. The lungs of the smoker are coated with tar and nicotine. These substances make the walls of alveoli stick to each other, thereby reducing the surface area available for respiration. So, the rate of respiration increases making it forced and noisy. It even thickens the mucous, making the respiratory path tight and congested and causing a difficulty in breathing.