help me out here...Between areas of myelin are non-myelinated areas called the nodes of Ranvier. Because fat (myelin) acts as an insulator, membrane coated with myelin will not conduct an impulse. So, in a myelinated neuron, action potentials only occur along the nodes and, therefore, impulses 'jump' over the areas of myelin - going from node to node in a process called saltatory conduction (with the word saltatory meaning 'jumping'):

what physical phenomena involves in this saltatory conduction?how does the impulse jump?

Question

help me out here...Between areas of myelin are non-myelinated areas called the nodes of Ranvier. Because fat (myelin) acts as an insulator, membrane coated with myelin will not conduct an impulse. So, in a myelinated neuron, action potentials only occur along the nodes and, therefore, impulses 'jump' over the areas of myelin - going from node to node in a process called saltatory conduction (with the word saltatory meaning 'jumping'):

what physical phenomena involves in this saltatory conduction?how does the impulse jump?

anonymous · Answer

The depolarisation of the membrane at the node is key to understanding this process. The action potential is sufficient to depolarise the adjacent node and so the action potential (AP) can travel along the axon. However the closing of sodium channels after depolarisation means that the AP can onlt travel in one direction. There's a good page here: http://en.wikipedia.org/wiki/Saltatory_conduction

anonymous · Answer

yes, that was nice one but my question is how depolarisation at one node of Ranvier  is sufficient to elevate the voltage at a neighboring end???what physical phenomena involves in the process?

anonymous · Answer

This is a good question now I have got the hang of it. The currents of ions are as follows: the initial flow is sodium entering the cell, which depolarises the membrane. This will cause lower potential at the next node, presumably because of a current of ions towards the depolarised node whcih has just fired. This decreases the polarisation at the next node, which depends on high sodium outside because of the sodium ions pumped out. The next phase is a potassium current caused by voltage - gated potassium channels. This tends to repolarise the membrane at the node which has just fired. There's a full description here: http://en.wikipedia.org/wiki/Action_potential

anonymous · Answer

its awesome and i'l get back after studying thoroughly with other resources also....it may take time....thanx ebaxter01 for your help

anonymous · Answer

the process of jumping of impulse can be calculated from CABLE THEORY....but how it is faster in the mylenated nerve fibres is not included in the theory...... http://en.wikipedia.org/wiki/Cable_theory...any idea for the calculation of time factor????