3. Use what you know about the physiology of neurons and action potential (AP) p

Question

3. Use what you know about the physiology of neurons and action potential (AP) propagation to answer the following questions. a. Imagine that you decrease the extracellular concentration of K' around a neuron. Would this bring the neuron closer to or further from, its threshold potential? b. Describe the subsequent effect on the resting potential: identify the ions responsible, and explain why they move as they do. c. Imagine that in a different neuron, voltage-gated K channels open quickly, only 0.3ms after voltage- gated Na" channels. Predict changes in timing, amplitude and shape of the AP (if any) by drawing one labeled diagram comparing a normal AP (solid line) to your AP (dashed line), and by explaining in words why these changes occur. Label the axes, depolarization and repolarization phases of your curve. (6) 4. Describe your perception of a pressure wave that initially stimulates many organs of corti, at about 5mm from the oval window, but steadily decreases the total number of organs it stimulates, and begins crossing the basilar membrane further and further from the oval window.

Explanation / Answer

If the concentration of K+ ion outside the cell were to decrease the driving force for potassium to move outside the cell would increase. Thus when concentration of K+ ion outside the cell were to decrease the cell potential become more negative. K+ ion being a cation means that if you decrease the amount of ionizing calcium ion in extracellular fluid it is nearly equivalent to having more positively charged intracellular fluid. This in turn means that the cell will be closer to its threshold potential.

In neurons, the resting film potential depends for the most part on development of K+ through potassium spill channels

Resting film potential is created by the blend of sodium and potassium pump and the break channels of these particles. The capacity of the pump is to take out three sodium from the cell and two potassium into the cell with the utilization of ATP (changes the state of pump to discharge these particles), as of now with the stoichiometry distinction, we see a charge contrast. Moreover, in light of the fact that it is more postive outside of the cell, and negative inside the cell, plasma film turns out to be more porous to Potassium on our break channels. Thusly, even with spill channels of the two particles, potassium is more porous. Causing a standard estimation of - 70mV resting potential

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