Action Potential

Question 1

action potential

Answer 1

a

Question 2

phases of action potential

Answer 2

rising phase, overshoot phase, falling phase, undershoot phase

Question 3

absolute refractory period

Answer 3

period during which it is not possible for the axon to have an action potential

Question 4

relative refractory period

Answer 4

period when it requires greater stimulation for the axon to produce another action potential.

Question 5

3 different voltage sensitive mechanisms

Answer 5

activation of sodium conductance, delayed activation of potassium conductance, inactivation of sodium conductance

Question 6

activation of sodium conductance

Answer 6

voltage dependent sodium channels open and sodium ions rush into cell, positive charge accumulates inside cell, depolarization of the membrane potential

Question 7

delayed activation of potassium conductance

Answer 7

after a delay, the voltage dependent potassium channels open and potassium ions rush out of the cell, reduction of positive charge inside cell, hyperpolarization of the membrane potential

Question 8

inactivation of sodium conductance

Answer 8

voltage dependent sodium channels transition to a non conductive state as voltage gated potassium channels begin to close. no longer sensitive to changes in membrane potential. stimulation does not result in action potentials. inactivation gates open and sodium channels close.

Question 9

voltage clamp approach

Answer 9

used to determine that sodium and potassium conductances change with time and membrane potential

Question 10

TTX (tetrodotoxin)

Answer 10

blocks sodium channels without affecting potassium channels. TTX is obtained from the puffer fish.

Question 11

TEA (tetraethylammonium bromide)

Answer 11

blocks potassium channels without affecting sodium channels and is also an ACh receptor blocker.

Question 12

Active flow

Answer 12

part of action potential propagation. gating of the voltage gated channels and associated influx of sodium ccurrent

Question 13

Passive current flow

Answer 13

part of action potential propagation. depolarization wave that precedes the action potential. positive ions entering axon via electrode or activated sodium channels passively move down the axon and neutralized negative membrane charges, decreasing the capacitive charge on the membrane and driving the membrane potential to threshold.

Question 14

myelination

Answer 14

wrapping of glial cell membranes around the axon. oligodendrocytes (CNS) and schwan cells (PNS). increases insulation reducing leak of passive flow. decreases capacitance.

Question 15

saltatory conduction

Answer 15

action potential jumps from node to node. disrupted in multiple sclerosis

Question 16

recall

Answer 16

nerve cells generate action potentials to transmit information over a distance to ultimately generate nonelectrical signals.