Case Study Chapter 22

Case Study Chapter 22

1. Intrapulmonary pressure and atmospheric pressure are the usually equal at 750mmHg (at sea level). During normal inspiration, muscles contract and pull on lungs increasing their volume. According to Boyle’s law pressure and volume are inversely proportional. This causes the intrapulmonary pressure to decrease, since there is a greater pressure outside of the lungs, air flows in from the atmosphere following pressure gradients. During normal expiration, as muscles relax, the lungs volume is reduced, increasing intrapulmonary pressure causing air to follow pressure gradients and flow out into the atmosphere.

2. Airway resistance is the friction encountered by air in the airways. The bronchial tree branches 23 different times, as airways gets smaller, there are more branches. Although individual bronchioles are tiny, there are tons of them parallel, leading to a huge cross-sectional area. Due to the large cross-sectional area in smaller bronchial tubes, the greatest amount of resistance takes place in the medium-sized bronchi.

3. Lung compliance is the degree of change capable in transpulmonary pressure, in other words the distensibility or “stretch” the lungs have. Alveolar Surface tension effects the lungs capability to exchange gases, it keeps alveoli easy to reinflate after exhalation and is regulated via surfactant. Lastly airway resistance is the friction encountered by air in the airways, gas is reduced as airway resistance increases. The one affecting Mike is airway resistance, as his airways are becoming inflamed and increasing airway resistance.

4. In order for for Mike to maintain normal air flow when his airways are inflamed, his intrapulmonary pressure must decrease more than it does during quiet inspiration, meaning the lungs must increase in volume more than normal. During exhalation, his transpulmonary pressure must increase more than it does during quiet expiration, meaning his lungs must...