"Into Thin Air" A Case Study in Physiology Part II Gasping for Air by Jennifer Lundmark Department of Biological Sciences California State University, Sacramento John, the assistant expedition leader and a seasoned alpinist, helped Tom guide Mark down the steep trail. Mark's breathing, increasingly labored with every passing moment, was loud enough to worry Emily and Pete, the expedition's final climber. "Geez, do we sound like that?" gasped Pete. "I mean, I'm out of breath, too, but he sounds horrible!" "No, we're not that bad. Remember, that's why we spent the prep month at 15,000 feet. Mark was with us, so he experienced the same physiological changes we did. This," Emily nodded at Mark, "is some sort of problem." Questions: 1. What physiological changes is Emily referring to (above) that will occur when someone lives at altitude for an extended period? 2. How are these changes advantageous?3. What is the specific physiological pathway that results in the changes described?