Compare the distribution of ion channels along unmyelinated versus myelinated axons and explain how this accounts for the difference in conduction velocity between these two types of axons. Predict the effects on action potential propagation of demyelinating diseases, such as multiple sclerosis.

Myelinated Axons; leak channels are insulated by myelin leading to less loss of current flow and better conduction velocity. Ion channels omly located at nodes of ranvier; thus signal has sultatory conduction along myelin sheaths and jumps and move much quicker

Demyelinating diseases; along locations where myelin sheaths once was current links occur and conduction slows, the signal cannot make it very far because it looses energy as it travels through the axon

Unmyelinated axon; Ion channels are sequentially placed all along axons; thus it takes longer to send signal down axon. the energy isn't leaked out, it still contains the same signal but it is simply slower. distance between voltage gated channels needs to be small enough so local current flow can depolarize the membrane.

N/B; Harder to generate action potential in demyelinating disease

axon diameter( bigger diameter= less resistance= faster current).

The speed of action potential conduction is faster in the myelinated neurons.

Myelinated Axons:

Unmyelinated axon:

Therefore, the speed of action potential conduction is faster in the mylinated neurons.

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