Tom is choking on a piece of steak that is stuck in his trachea, and he signals for his young son to call 911. It takes the paramedics four minutes to reach his house. Will this be in time to save Tom (and why), or will Tom already be dead (and why)?

Question

A.  Tom will be alive since the myoglobin in his muscles will release oxygen into the blood after he stops breathing.
B.  Tom will be dead due to the lowered pH of his blood.
C.  Tom will be dead since all the hemoglobin in his arterial blood will unload its oxygen during the first pass through the tissues after his last breath.
D.  Tom will be alive since he had a reserve of about three-quarters of his hemoglobin still bound to oxygen when he started choking.


Clarify Question
What is the key concept addressed by the question?
What type of thinking is required?
 
Gather Content
What do you already know about oxygen transport? What other information is related to the question?
 
Choose Answer
Given what you now know, what information is most likely to produce the correct answer?

Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
 

Answer 1

D.  Tom will be alive since he had a reserve of about three-quarters of his hemoglobin still bound to oxygen when he started choking.

Clarify Question
What is the key concept addressed by the question?
        · This question is asking about whether humans can survive the lack of oxygen for any period of time.
What type of thinking is required?
        · Apply level:
            o You are being asked to take what you already know and use, or apply, it to a situation in which oxygen deprivation occurs for a short time.
 
Gather Content
What do you already know about oxygen transport? What other information is related to the question?
        · Blockage of the trachea prevents oxygen from reaching the lungs.
        · As the final electron acceptor in cellular respiration, oxygen is critical for survival.
        · Hemoglobin carries oxygen to the tissues from the lungs.
        · At rest, most of the oxygen that is bound to hemoglobin remains in the blood.
 
Choose Answer
Given what you now know, what information is most likely to produce the correct answer?
        · Myoglobin binds with oxygen and stores it muscle tissue. This oxygen is used within muscle, but is not released back into the blood.
        · Although increased carbon dioxide in the blood does lower pH, the effects of this change would take longer to become fatal than lack of oxygen.
        · The majority of oxygen does remain bound to hemoglobin, which creates a limited reserve if breathing is interrupted.
 
Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        · Apply level:
            o Answering this question correctly depended on your ability to use the nature of hemoglobin in a new situation. If you got an incorrect answer, did you remember that hemoglobin carries oxygen in the blood, or that hemoglobin does not immediately release all of the oxygen that it carries? Did you have trouble extending the nature of hemoglobin to determine the correct answer?