A nerve cell has an axon that extends 3 cm with an internode

A nerve cell has an axon that extends 3 cm with an inter-node spacing of 2 mm. calculate the membrane potential at a node just prior to the generation of an action potential given the following information: Membrane length constant = 1 mm Threshold = 35 mv Resting membrane potential (RMP) = -60 mV Action potential overshoot = +20 mv. What is the membrane potential at the next node, and is depolarization sufficient to generate another action potential? %Response = 100(1 - e^) -49 mV and an AP will NOT occur at node 2 -30 mV, and an AP WILL occur at node 2 -69 mv. and an AP WILL occur at node 2 -25 mV, and an AP will NOT occur at node 2 Explain how the length constant is affected following degradation of the myelin sheath, or in other words, how is the length constant affected by decreases in membrane resistance (Rm)? How does demyelination affect conduction along the axon? Name one disease that causes demyelination.

Solution

ans.

3. Disease which cause demylination is multiple sclerosis which is the most common demylinating disease. immune system of individual starts attacking own nerve cell and dgrading myelin sheath.

2. Effect of demylenation on conduction of nerve impulse is as follows

If severe demylenation is present it will lead to total loss of nerve conduction.

whereas less severe demylination allows continued transmission of the nerve impulse but the rate of conductance is slowed down owing to slow conduction velocity and shows a characterstics inabilty to transmit faster rate of impulse because of increase refractoriness in nerve after single imulse transmission