Gasping for Air John, the assistant expedition leader and a seasoned alpinist, h
ID: 3479375 • Letter: G
Question
Gasping for Air
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."
Part II Questions
Fill in the following table about the hormone that was released when the expedition spent their prep month at 15,000 feet.
Source of Hormone Stimulus for Release Target TissuePhysiological Hormone ResponseExplanation / Answer
Mark was not able to breath well due to the increase in 2,3BPG levels in his body. Synthesis of 2,3BPG increases in higher altitudes where oxygen concentration is low. It binds to deoxygenated hemoglobin subunits and mediates the removal of oxygen from other subunits of hemoglobin. It favors deoxygenation of hemoglobin. It is synthesized by BPG mutase.
Several studies analyzed the cause for increased 2,3BPG levels. The results showed that thyroid hormone increases the expression of BPG mutase and leads to increased synthesis of 2,3 BPG
Hormone
Source
Stimulus for release
Target
Response
Thyroid hormone (responsible for increased BPG mutase)
Thyroid gland
Low oxygen levels
Red blood cells
Deoxygenation
Hormone
Source
Stimulus for release
Target
Response
Thyroid hormone (responsible for increased BPG mutase)
Thyroid gland
Low oxygen levels
Red blood cells
Deoxygenation
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