Explain, physiologically, how the amount of myelination surrounding a neuron imp

Question

Explain, physiologically, how the amount of myelination surrounding a neuron impacts conduction velocity through that neuron. Be sure to explain the physiology of why this occurs, and include data from the activity to support your answer.

Time (msec) Timescale Axon Type Myeltone im)R to )(msec) Stimulus Distance From R1 to R2 (m) 0.1 0.1 0.1 Time Between APs at R1 and R2 Axon Type A fiber B fiber C fiber Myelination Voltage 30 30 30 Heavy Light None 2 10 100 (sec) 002 010 Conduction Velocity (m/sec) 2/.002 2/.010 21.1 Record Data

Explanation / Answer

To begin with the answer,basic thing is to know the Myelination. " Myelination" is the process of coating the axons of the neurons with a protein (fatty coating) called Myelin.This Myelination helps to protect and conduct the transmission of the signals (impluses) through neurons.

Myelination increases the conduction velocity,Myline protein acts as an electrical insulator which inceases the action potential. The action potential travels through the axon as an ion cascade(inflow of the Na+) in the cell.These Na+ ion stimulates the transmembrane channels to open up(which are at the front of the axons) and inflow becomes more.This is the cycle happens through the axon and result in the action potential.More the myeline and more the Diameter of axon more is the signal transmission .

These action potential generation happens at specific point in the axons called the "Node of Ranvier"(periodic gap in the myeline sheeth) helps to increase the current flow in the segment untill the next node is reach. This phenomenon (jumping from one node to another ) helps to increase the implus transmission much more. Thus myelinated axons transmit the signals faster due to these periodic gap (Node of Ranvier) as compared to the unmylinated axons.

So in the above activity,Axon type fiber A which has got the heavy amount of Myelin conducts the signal transmission at a heigher rate due to the presence of the periodic gap (node of Ranvier) because as the axon is heavily insulated the current cannot loss elsewhere,it will just reach to the node fast (that means the occurence of the action potential time is also less) and will jump to the other node,so only the conduction velosity (2/.002)m/sec.

whereas you can see the Axon type fiber B transmit the impulses in little less as compared to the Fiber A because the amount of myeline is little less here so amount of current during movement gets lost as some points till it reaces to the next node of ranvier,thats how here the conduction velocity is 2/.010 m.sec.

And the Axon type Fiber C which is Unmyelinated thats means no insulation along the axon,the current flows gets loss continously as a result these axons transfer the signals in very very slow rate as compared to the mylinated axons,thus only the conduction velocity is less (2/.1)m/sec.

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