Bio/Biochem CR Question: Section 4 Question 45

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Bio/Biochem CR Question: Section 4 Question 45

Postby ArielM » Thu Nov 16, 2017 9:54 pm

Question 45 asks:

Which of the following initiates systole?
A. Contraction of atria
B. Relaxation of ventricles
C. Contraction of ventricles
D. Relaxation of atria

The correct answer is C, contraction of ventricles. Just to make sure, is this question asking what initiates, as in comes right before, systole? Also, is this question asking about atrial or ventricular systole? In the cardiac cycle, doesn't atrial systole come before ventricular systole? I've included an attachment.
Wiggers Diagram.pdf
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Re: Bio/Biochem CR Question: Section 4 Question 45

Postby NS_Tutor_Andrew » Tue Nov 28, 2017 6:06 pm

Hi ArielM,

Thanks for the excellent question! I believe this question is asking about ventricular systole, which is where the blood is pushed out into the body (and what is responsible for the pulse). However, you're right that this question could be clearer in terms of specifying ventricular vs. atrial systole -- we'll make a note of it!

In terms of the wording of the question, "initiates" is meant to mean more like "what causes it to start/happen" -- that is, it's not just that contraction of the ventricles happens before ventricular systole, but that contraction of the ventricles can be thought of as what "drives" ventricular systole. (Of course, ventricular contraction has its own causes, but we're not being asked to follow the cause-and-effect chain that far back).

Hope this is helpful, and keep up the great questions!
Andrew D.
Content Manager, Next Step Test Prep.

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