Aamc 8 bs #110

[dougkaye]

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This one was strange. Passage gives

blood pressure = cardiac output (CO) x vasc resistance (VR).

It asks which type of muscle's enhanced activity will increase blood pressure. I said cardiac muscle because according to equation, if CO increases while VR stays the same, BP will increase. Why is this not a valid answer? The passage does mention vasoconstriction being a cause of hypertension, but according to the passage information, increased CO can ALSO cause htn. hmm...

 

[rrmix]

This one was strange. Passage gives

blood pressure = cardiac output (CO) x vasc resistance (VR).

It asks which type of muscle's enhanced activity will increase blood pressure. I said cardiac muscle because according to equation, if CO increases while VR stays the same, BP will increase. Why is this not a valid answer? The passage does mention vasoconstriction being a cause of hypertension, but according to the passage information, increased CO can ALSO cause htn. hmm...

I think your missing something in the passage or question, but the since smooth muscle lines the the vessels if you vasoconstrict, the diameter decreases, therefore the velocity of the blood must also increase. For this to happen CO must increase. *Barring blood is not an ideal fluid, but it still works.

 

[SmokeyJunior]

two ways to have approached that question.
It says according to hypothesis A, enhanced activity of which of the following basic muscle types ....
Under hypothesis A it says "enhanced muscle tone in the vessel walls (vaso-constriction) may be the major cause of systematic hypertension.

Also the answer choices list
Striated
Smooth
Cardiac
Multinucleate

Cardiac and multinucleate are striated muscle types. Smooth isn't striated.

Ps also got that question wrong when going through it, quickly jumped the gun and when with cardiac. Gotta slow down :|

 

[dougkaye]

two ways to have approached that question.
It says according to hypothesis A, enhanced activity of which of the following basic muscle types ....
Under hypothesis A it says "enhanced muscle tone in the vessel walls (vaso-constriction) may be the major cause of systematic hypertension.

Also the answer choices list
Striated
Smooth
Cardiac
Multinucleate

Cardiac and multinucleate are striated muscle types. Smooth isn't striated.

Ps also got that question wrong when going through it, quickly jumped the gun and when with cardiac. Gotta slow down :|

I understand your reasoning for why smooth muscle works. But again, based on passage information, CO increasing, and all other factors remaining equal, will increase BP as well. Hence my original argument for cardiac muscle.

 

[SmokeyJunior]

don't disagree. Hmm the the vessel walls are made of smooth muscle. So if according to the passage the major cause (meaning there are other causes) being enhanced (i guess the word enhanced was the hint) muscle tone in the vessel walls. Then CO increasing may indeed cause things to increase but vaso constriction would contribute much more. Sighh this test.....

 

[KhaoticKarma]

this one was bugging me too...until i read the question over. It asks about HYPOTHESIS A specifically. This means that yes, while cardiac out put CAN increase with cardiac muscle usage, it has nothing to do with hypothesis A. B/c hypothesis A is concerned with vasoconstriction of the vessels.

 

[ThirdEye]

This one was strange. Passage gives

blood pressure = cardiac output (CO) x vasc resistance (VR).

It asks which type of muscle's enhanced activity will increase blood pressure. I said cardiac muscle because according to equation, if CO increases while VR stays the same, BP will increase. Why is this not a valid answer? The passage does mention vasoconstriction being a cause of hypertension, but according to the passage information, increased CO can ALSO cause htn. hmm...

Because the passage says vasoconstriction is a cause of hypertension, you can't go against vasoconstriction. People who are hypertensive aren't so because they have a crazy cardiac output but because they have vascular resistance(due to vasoconstriction). This is a fact that you should know, and if you don't... now you do.