Nerve firing master

Question 1

Resting potential (1st phase)

Answer 1

Voltage differences in nerve cells are a result of pumping sodium ions out of the cell and potassium ions into the cell through the Na-K pump

 Creates a neuron with a negatively charged interior relative to the exterior ~-70mV.

Question 2

Depolarization

Answer 2

A stimulus causes a gate in the Na+ Channel to open

 Since there is a high concentration of Na+ outside, Na+ diffuses into the neuron.

 The electrical potential changes to +30 mV or more.

Question 3

repolarization

Answer 3

Depolarization causes the K+ Channel gate to immediately open.
 K+ diffuses out of the neuron.
 This reestablishes the initial electrical potential of ~-70
mV.

Question 4

Refractory period

Answer 4

During this time (~ 1 msec), the Na+ and K+ Channels cannot be opened by a stimulus.
 The Na+/K+ Pump actively pumps Na+ out of the neuron and K+ into the neuron.
 This reestablishes the initial ion distribution of the resting neuron.