Why does the build-up of tar in the bronchi limit air flow?

Case Study- Smoking and Lung Cancer Cancer usually begins in the bronchi or bronchioles. Components of cigarette smoke contribute to the development of cancerous tumours. Study the four diagrams below, which show the development and progression of lung cancer. Listen to the video about the effects of smoking in our lungs using the link below. https://www.youtube.com/watch?v=69R0E_Rg_mQ If It is not open in your computer please open on the phone 1. Cigarette smoke travels through the bronchi and irritates the cells. Goblet cells produce mucus, which is designed to trap foreign particles. Compare the mucous layers in diagrams A and B. a) How has cigarette smoke affect the mucous layer? 2 Ciliated cells line the bronchi. Cilia sweep away the debris trapped by the mucus. Unfortunately, the tar found in cigarette smoke slows the action of the cilia. The sludge-like tar becomes trapped in the mucus. b) Why does the build-up of tar in the bronchi limit air flow? 3 Diagram B shows the beginning of a cancerous tumour. c) In what area does the tumour begin to develop? 4 Diagram C shows how the tumour begins to grow. d) Why has the mucous layer in diagram C decreased in size?