HMX Physiology 166 Questions with 100% Verified Correct Answers

HMX Physiology 166 Questions with 100% Verified Correct Answers A healthy 21 year old man is mountain climbing in Nepal and is at an altitude of approximately 3,000 meters. Barometric pressure is 530 mm Hg. He is feeling short of breath and the climbing is becoming more difficult. The partial pressure of oxygen in the air he is breathing is approximately: 150 mm Hg 220 mm Hg 110 mm Hg 35 mm Hg - Correct Answer 110 mm Hg Explanation: Atmospheric pressure at sea level is 760 mmHg or one atmosphere (atm). As we ascend, the pressure decreases (~0.012 atm or 9mmHg per 100 meters) and thus the partial pressures of atmospheric gases drop (even though the composition or percentages remain the same). Partial pressure of a gas is calculated as the concentration (percentage) of that gas multiplied by the atmospheric pressure (Pgas = Patm (Fgas) ). Air is composed of 78% nitrogen (N2) and 21% oxygen (O2) and 1% other gases (these values are sometimes simplified to 79% N2 and 21% O2 for calculations). Thus the PO2 or partial pressure of oxygen is 0.21 X 530 = 111.3 or about 110mmHg. It's New Year's Eve and you are eager to drink some champagne. Unable to wait until midnight, you open a bottle and pour yourself a glass. Your date comes by and tells you to recork the bottle, which you promptly do. Several minutes later the champagne is no longer "bubbling." The partial pressure of carbon dioxide in the bottle above the champagne is now: The same as in the partial pressure of CO2 in the atmosphere The same as the partial pressure of CO2 in the champagne Less than the partial - Correct Answer The same as the partial pressure of CO2 in the champagne Explanation: Carbon dioxide (CO2) is dissolved in solution under high pressures as in a champagne bottle. When the cork is removed the high pressure in the bottle begins to equalize with atmospheric pressure outside the bottle. As the pressure rapidly decreases in the bottle, CO2 begins to come out of solution and is represented as bubbles. When the cork is reinserted into the bottle, CO2 coming out of solution begins to accumulate as a gas in the bottle and the PCO2 in the gaseous state increases. When the bubbling ceases, the partial pressure of CO2 in the gaseous state in the bottle equals the PCO2 dissolved in the liquid (champagne). Consequently, the PCO2 in the bottle is greater than the PCO2 in the atmosphere (where it is essentially zero). We cannot know with certainty how much greater the PCO2 is in the gaseous phase in the bottle compared to the atmosphere. Imagine you are on the planet Venus where the atmospheric pressure is ~92 atm (1 atm = 760 mmHg). What are the partial pressures of the component atmospheric gases, given gas fractions of 96.5% CO2 and 3.5% N2? PCO2 96.5 atm; PN2 3.