PSIO 420 exam 3 key - PSIO 420/520 practice problem set #3:...

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PSIO 420/520 practice problem set #3: The respiratory system 1. a. Calculate alveolar ventilation (VA) given the following data: VD = 200 ml/breath VT = 2.5 L/breath FB = 50 b/min VA = (2.5 L/br - 0.2 L/br) (50 br/min) = 115 L/min b. During exercise, large tidal volumes are achieved despite a much lower time available for each breath (since FB has increased). How is this accomplished? By increasing respiratory muscle recruitment, there is an increase in the pressure gradient between the lung and atmosphere, thus facilitating faster air flow 2. The following figures illustrate the relationship between tidal volume and breathing frequency during a progressive intensity exercise test. A B 10% 100% %VO2max 10% 100% a. Which figure represents tidal volume? A B b. At rest, increasing tidal volume increases the quantity of ______ elastic _______ (elastic / resistive) work done by the respiratory muscles. c. At rest, increasing breathing frequency will increase the quantity of _______ resistive _____ (elastic / resistive) work done by the respiratory muscles. d. Given what you know about respiratory muscle work, briefly explain why tidal volume and breathing frequency change the way they do during exercise above 50% VO2max. Since lung compliance decreases at high volumes, it’s too much elastic work to increase VE by increasing V T beyond a certain point. It’s favorable to increase FB to increase VE. While resistive work does increase, the work of breathing is minimized (especially with bronchodilation). 3.
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This note was uploaded on 05/13/2008 for the course PSIO 420 taught by Professor Keen during the Spring '08 term at University of Arizona- Tucson.

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PSIO 420 exam 3 key - PSIO 420/520 practice problem set #3:...

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