The permeability of the axon membrane to NA+ and K+ depends on what?

and how and what is it called as ions flow?

gated channels that open in response to simulation.  Na moves in the K moves out. 

This flow of ions and changes in the membrane potential constitute and event called and action potential.

all cells in the body maintain a potential diffference

(voltage)

across the membrane.

this resting membrane potential where the inside is negative compared to outside.  

only a few cells alter their membrane potential in response to stimule..

only a few types of cells react to stimuli.

this is a cental aspect of the physiology of neurone and muscle cells....to produce and conduct changes in membrane potental.   that is called excitability or irritability

Diffusion of that ion down its electrochemical gradient (concentration and electrical gradients considered together)

either into or out of the cell  across places where ion channels are located.

can be measured in voltage

stimulation causes positive charges to flow into the cell  and the line will deflect upward. 

it means the potential difference between the two recording electrodes is reduced.

..line on oscilloscope will deflect downward

if it causes the inside of the cell to become more negative than the resting membrane potential

the changes in membrane potential--

depolarixation, repolarization, hyprpolarization are caused by what?

when the plasma membrane is freely permeal tot Na for an instant ...

the membrane potential moves rapidly toward Na+ equilibrium potential....and even though small it greatly affects the membrane potential

explosive increase in Na permeability results is a rapid reversal of membrane potential in that region   from-7- mV to + 30 mV