What is pleurisy

What is pleurisy - What is pleurisy? . BREATHING (PULMONARY...

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What is pleurisy? . BREATHING (PULMONARY VENTILATION ) A. Breathing consists of two phases: inspiration (the period when air flows into the lungs) and expiration (the period when gases exit the lungs). B. Pressures Associated with Breathing 1. Atmospheric Pressure(P atm )-the pressure exerted by the air (gases) surrounding the body. At sea level, atmospheric pressure is 760 mm Hg (or 1 atm). a. A negative respiratory pressure indicates that the pressure in that area is less than atmospheric pressure. The opposite is also true. 2. Intrapulmonary Pressure (P pul ) is the pressure in the alveoli. It rises and falls with the phases of breathing but it always eventually equalizes with atmospheric pressure. 3. Intrapleural Pressure (P ip )-pressure in the pleural cavity. This is always about 4 mm Hg less than P pul ; therefore, P ip is always negative relative to P pul . a. How is this negative pressure established ? 1) By the natural recoil of the lungs -the lungs are elastic, so they tend to assume the smallest size possible. 2) Due to the surface tension of the alveolar fluid -alveolar fluid surface tension draws the alveoli to their smallest size. b. However, the above 2 forces are countered by the natural elasticity of the
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What is pleurisy - What is pleurisy? . BREATHING (PULMONARY...

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