Solns prob set #4

Solns prob set #4 - BIPN 108, Physiology of...

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BIPN 108, Physiology of Exercise--Solutions to problem Set #4 Page 1 1. a. The resistance to air flow in the respiratory passages, like the resistance to blood flow in blood vessels, is described by Poiseuille’s law, which states that resistance increases with r 4 . Even small decreases in diameter (which would be produced by contraction of smooth muscles in the walls of the respiratory passages) increase the resistance to air flow. Because Q = P/R, an increase in resistance required a compensatory change in pressure difference between the outer atmosphere and the lungs in order for airflow to be held constant. Atmospheric pressure is fixed, so the only way to increase the pressure difference between the outside air and the inside of the lungs is to decrease the pressure inside the thoracic cavity. The ideal gas laws tell us that PV = nRT, so the only way to decrease the pressure inside the thoracic cavity is to increase its volume. Increasing the volume means increased contraction of the muscle of respiration, which are red oxidative fibers. As a result, when they must contract more, they also use more O 2 , leaving less O 2 for other working muscles. b. Smoking has a lot of adverse effects, but because power lifting is a very high-intensity, short duration event, and hence it does not depend on oxidative metabolism, smoking just before a lift is unlikely to affect the performance. c. On the other hand, a 5-minute long dance performance must use at least some oxidative metabolism, and increasing the resistance to airflow through respiratory passages will cause the dancer to have to work even harder than she otherwise would, which could affect the quality of her performance. 2. a. The average tidal volume of a normal healthy adult at rest is about 0.5 liters (page 301, Fig. 9.6). b.
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This note was uploaded on 04/19/2008 for the course BIPN 108 taught by Professor French during the Winter '08 term at UCSD.

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Solns prob set #4 - BIPN 108, Physiology of...

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