TPR myelin question

[Meredith92]

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This is from the bio review book. Which one of the following is true concerning myelinated and unmyelinated axons?
A. the total amount of energy consumed by all the Na+/K+ ATPases is much less in myelinated axons than in unmyelinated axons
B. Myelinated axons can conduct many more action potentials per second than cna unmyelinated axons.

(C and D i ruled out)
The answer is A, which made sense but i felt like B was for sure the right answer. Im a neuroscience major and I know that axons that are unmyelinated will have a really rough time conduction action potentials because it will be much slower/ the signal will die out sooner... wouldnt this make B the right answer?? myelinated axons definitely conduct action potentials faster and better!!

Thanks for your help- this question is bothering me!

 

[Postictal Raiden]

I could be wrong but here's my speculation:

Due to the refractory period, the period through which another action potential can't be generated, there is a fixed number of action potential that can occur in a given time period. Therefore, regarding of the conduction speed, the refractory period dictates the maximum number of action potential that could occur in any given second.

BTW, I would have chosen option B if you didn't point out the correct answer.

 

[Temperature101]

This is from the bio review book. Which one of the following is true concerning myelinated and unmyelinated axons?
A. the total amount of energy consumed by all the Na+/K+ ATPases is much less in myelinated axons than in unmyelinated axons
B. Myelinated axons can conduct many more action potentials per second than cna unmyelinated axons.

(C and D i ruled out)
The answer is A, which made sense but i felt like B was for sure the right answer. Im a neuroscience major and I know that axons that are unmyelinated will have a really rough time conduction action potentials because it will be much slower/ the signal will die out sooner... wouldnt this make B the right answer?? myelinated axons definitely conduct action potentials faster and better!!

Thanks for your help- this question is bothering me!

Both answers are OK to me...This might be a mistake...

 

[Hemorrage]

This is from the bio review book. Which one of the following is true concerning myelinated and unmyelinated axons?
A. the total amount of energy consumed by all the Na+/K+ ATPases is much less in myelinated axons than in unmyelinated axons
B. Myelinated axons can conduct many more action potentials per second than cna unmyelinated axons.

(C and D i ruled out)
The answer is A, which made sense but i felt like B was for sure the right answer. Im a neuroscience major and I know that axons that are unmyelinated will have a really rough time conduction action potentials because it will be much slower/ the signal will die out sooner... wouldnt this make B the right answer?? myelinated axons definitely conduct action potentials faster and better!!

Thanks for your help- this question is bothering me!

This is a really nit-picky question. If you pick up a physiology book, most of them will state that myelination increases conduction velocity, NOT frequency. A is the correct answer by default if you cross out B,C,D even if you're not sure about the energy usage. A is definitely right because energy usage is one of the evolutionary advantages of myelination. By condensing the Na+/K+-ATPases to a specific region (increasing density) (nodes of ranvier) you're able to restore the ion concentrations more efficiently than if you had an unmyelinated axon with ATPases spread out. This means you spend LESS ATP overall restoring the ion concentrations with nodes.

 

[Meredith92]

This is a really nit-picky question. If you pick up a physiology book, most of them will state that myelination increases conduction velocity, NOT frequency. A is the correct answer by default if you cross out B,C,D even if you're not sure about the energy usage. A is definitely right because energy usage is one of the evolutionary advantages of myelination. By condensing the Na+/K+-ATPases to a specific region (increasing density) (nodes of ranvier) you're able to restore the ion concentrations more efficiently than if you had an unmyelinated axon with ATPases spread out. This means you spend LESS ATP overall restoring the ion concentrations with nodes.

okay thanks that makes sense!