Local control of breathing the smooth muscle in the

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Local Control of Breathing The smooth muscle in the walls of the bronchioles is very sensitive to the concentration of carbon dioxide. A rising level of CO 2 causes the bronchioles to dilate. This lowers the resistance in the airways and thus increases the flow of air in and out. Diseases of the Lungs Pneumonia Pneumonia is an infection of the alveoli. It can be caused by many kinds of both bacteria (e.g., Streptococcus pneumoniae) and viruses. Tissue fluids accumulate in the alveoli reducing the surface area exposed to air. If enough alveoli are affected, the patient may need supplemental oxygen. Asthma In asthma, periodic constriction of the bronchi and bronchioles makes it more difficult to breathe in and, especially, out. Attacks of asthma can be triggered by airborne irritants such as chemical fumes and cigarette smoke airborne particles to which the patient is allergic .
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CHE-4284/CHE-5292 Industrial Safety _ _______________________________________________________________________ 5 Emphysema In this disorder, the delicate walls of the alveoli break down, reducing the gas exchange area of the lungs. The condition develops slowly and is seldom a direct cause of death. However, the gradual loss of gas exchange area forces the heart to pump ever-larger volumes of blood to the lungs in order to satisfy the body's needs. The added strain can lead to heart failure. The immediate cause of emphysema seems to be the release of proteolytic enzymes as part of the inflammatory process that follows irritation of the lungs. Most people avoid this kind of damage during infections, etc. by producing an enzyme inhibitor (a serpin ) called alpha-1 antitrypsin . Those rare people who inherit two defective genes for alpha-1 antitrypsin are particularly susceptible to developing emphysema. Chronic Bronchitis Any irritant reaching the bronchi and bronchioles will stimulate an increased secretion of mucus. In chronic bronchitis the air passages become clogged with mucus, and this leads to a persistent cough. Chronic bronchitis is usually associated with cigarette smoking. Chronic Obstructive Pulmonary Disease (COPD) Irritation of the lungs can lead to asthma, emphysema, and chronic bronchitis. And, in fact, many people develop two or three of these together. This constellation is known as chronic obstructive pulmonary disease ( COPD ). Among the causes of COPD are cigarette smoke (often) cystic fibrosis (rare) Cystic fibrosis is a genetic disorder caused by inheriting two defective genes for the c ystic f ibrosis t ransmembrane conductance r egulator ( CFTR ), a transmembrane protein needed for the transport of Cl -
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  • Summer '13
  • Pozo
  • pH, Chronic obstructive pulmonary disease

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