An action potential in one segment of axon causes adjacent sections of axon membrane to reach threshold through what mechanism?
na+ ions diffusing across the membrane through leakage channels the generation of local currents
k+ ions diffusing through voltage-gated channels neurotransmitters causing chemically gated channels to open

Na+ ions diffusing across the membrane through leakage channels the generation of local currents

Explanation:

An action potential occurs when the membrane potential of a specific cell location rapidly rises and falls. There is a voltage difference between the exterior and interior of the cell, called the membrane potential, due the Na+/K+ ATPase pump.  

Starting from the resting potential, the action potential starts when the thershold is reached when Na+ ions difusse across the membrane through channels.Then, the interior of the cell becomes positive and the exterior negative.

The K+ channels take place when the repolarization phase stars, letting K+ ions difusse from the inside of the cells to the exterior.  

answer : (a) volume of the gas = 8.67 ×   l

                (b) second virial coefficient b = -1.21226 l/mole

solution :   given,     t = 300k

                                p = 20atm

                                z = 0.86

                                n = 8.2 mmoles = 8.2 × moles

                                r =   0.082 l atm/k/mol

        find,     (a) volume of gas   and (b) second virial coefficient b at 300k.

formula used :            

                          and            

(a)            

                    = \times 0.082\times 300}{20}[/tex]

                    = 8.67 ×   l

(b)      

                    = (0.00867-1) × 8.659

                    = - 8.5839 l/mole