Action Potential: Conducting Velocity
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| What happens once the action potential is generated? (2) | It is propagated or conducted down the axon. This propagation ensures that the amplitude of the axon does not diminish as it is conducted along the axon.
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| Why does propogation/conduction occur? | B/c there are voltage gated sodium and potassium channels located along the axon & b/c the large depolarisation that constitutes the action potential easily brings the next region of the axon to threshold.
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| How can conduction velocity be calculated? | By knowing the distance the action potential travels and the amount of time it takes
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| What influences the conduction velocity of an axon? | axon diameter & amount of myelination
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| What is myelination? | special wrapping of the membrane from glial cells around the axon
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| What are the names of the glia that wrap around the axons in the CNS and PNS? | CNS: Oligondendrocytes
PNS: Schwann Cells
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| How are myelin sheaths separated? | by gaps called nodes of Ranvier
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| Action potential conduction velocity is fastest in which of the following fibers? | A fibers (large diameter, heavily myelinated)
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| Action potential conduction velocity is slowest in which of the following fibers? | C fibers
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| Why did the timescale have to be changed to measure the conduction velocity of the C fibers? | The total time shown on the oscilloscope would have been too short to see the action potential at R2.
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| The axons from touch fibers are A fibers, and the axons from pain fibers are C fibers. When you stub your toe, which would you expect to perceive first? | your toe touching something
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| How did the conduction velocity in the B fiber compare with that in the A Fiber? How well did the results compare with your prediction? | B fiber conduction was much slower than A fiber
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| How did the conduction velocity in the C fiber compare with that in the B Fiber? | C fiber conduction was slower than B fiber.
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| What is the effect of axon diameter on conduction velocity? | The larger the axon diameter, the greater the conduction velocity.
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| What is the effect of the amount of myelination on conduction velocity? | The greater the amount of myelination, the greater the conduction velocity.
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| Why did the time between the stimulation and the action potential at R1 differ for each axon? | The time between the stimulation and the action potential at R1 differed for each axon because the axon diameter and amount of myelination varied for each axon.
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| Why did you need to change the timescale on the oscilloscope for each axon? | This is necessary in order to see the action potentials. The velocity changes so when it gets very slow you need a longer time scale.
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Created by:
meunid