Respiratory diseases Breathing is the process of taking in and using oxygen. There are three different phases of respiration: external respiration, internal respiration and cellular respiration. External respiration is the intake of oxygen from the environment and the release of carbon dioxide. In internal respiration, oxygen is transported to the cells and carbon dioxide is carried away from the cells. In cellular respiration, oxygen is used in chemical reactions within cells. Some respiratory diseases are: bronchial asthma, common cold and diphtheria. Bronchial asthma is a disease in which the bronchial passages are narrowed and swelling of the mucous lining causes blocked breathing, usually due to dust, animal fur or feathers, or pollen. Many people suffer from asthma caused by allergies, called extrinsic asthma, they usually suffer from hay fever. Non-allergic asthma, which adults usually have, is called intrinsic asthma. Intrinsic asthma is usually caused by respiratory infections and emotional disorders. A typical asthma attack begins with coughing, wheezing, and shortness of breath. Some people have a dry cough as their only symptom. Attacks usually last only a couple of hours. An attack can recur a few hours or even years after the first attack. Asthma attacks can be treated and prevented with the use of medications. The usual treatment is albuterol or terbutaline, which can bring relief within minutes. The common cold is another disease of the respiratory system. The cold affects the mucous membranes of the nose and throat. Causes nasal congestion, sore throat and cough. A cold usually lasts up to seven days on average. There is still no known cure for the common cold. Diphtheria is another respiratory disease that, in most cases, affects