In this episode on the basics of asthma I explain about the role of the lungs, and why asthma is a potentially dangerous disease. Different types of asthma are described. Information on the ongoing, chronic, inflammation caused by asthma as well as the fact that asthma flares up with attacks is discussed. Also the episode includes a detailed explanation of how asthma affects the lungs, particularly how the air passages are narrowed due to swelling and tightening (spasm) of their walls results in their obstruction. As a result when asthma flares up (also called an exacerbation or an attack) the person develops respiratory symptoms and it becomes difficult to breathe, and the body gets short of oxygen which is dangerous. This basic information about asthma may also help you to understand the basics of how the different asthma drugs may work.