Four-year old Sammy is having a temper-tantrum. In a final attempt to get his way, he yells to his mom, “I'm gonna hold my breath ‘til I die!” What is the primary reason that Sammy’s mom is unconcerned by this statement?

Question

A.  It is impossible for Sammy to control the contraction of his diaphragm and intercostal muscles since they are made up of smooth muscle.
B.  As Sammy holds his breath, the decreasing levels of oxygen in his blood will lead to stimulation of the respiratory control center in his brain.
C.  Sammy is too young to hold his breath for more than 30 seconds.
D.  As Sammy holds his breath, the increasing levels of carbon dioxide in his blood will lead to stimulation of the respiratory control center in his brain.


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 respiration? 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.  As Sammy holds his breath, the increasing levels of carbon dioxide in his blood will lead to stimulation of the respiratory control center in his brain.

Clarify Question
  What is the key concept addressed by the question?
        · This question is asking you to explain the regulation of breathing.
What type of thinking is required?
Choose from the following samples to streamline your writing:
        · Apply level:
            o You are being asked to take what you already know and apply it to the involuntary initiation of breathing.

Gather Content
What do you already know about respiration? What other information is related to the question?
        · A normal child that voluntarily holds his or her breath does not suffocate, as breathing resumes within a few seconds.
        · The respiratory control center stimulates an individual to take a breath.
        · As carbon dioxide accumulates in the blood, the pH of the blood decreases.
        · A decrease in the pH of the blood is detected by chemoreceptors, which in turn stimulate the respiratory control center to initiate a breath.
 
Choose Answer
Given what you now know, what information is most likely to produce the correct answer?
        · The diaphragm and intercostal muscles are skeletal muscles, not smooth muscles, and are therefore under voluntary control.
        · It is changing carbon dioxide levels, not changing oxygen levels, that stimulate the respiratory control center.
        · As Sammy .holds his breath, carbon dioxide would build up, and pH would decrease. Decreased pH would stimulate the respiratory control center and Sammy would take a breath.
 
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 regulation of breathing in a new situation. If you got an incorrect answer, did you remember that breathing is stimulated by the respiratory control center, or that increased carbon dioxide lowers pH and stimulates the respiratory control center? Did you have trouble extending the regulation of breathing to determine the correct answer?