Resting Potential

Question 1

What is resting potential?

Answer 1

Resting potential: it is the potential difference between the surface(extracellular medium)
and the cross section(intracellular medium) at rest , without any stimulation . at rest the surface is positively charged and the cross section is negatively charged. This potential
difference at rest is equal to -70 mv.

Question 2

What is the origin (Chemical Cause) of resting potential?

Answer 2

the plasma membrane of the neuron has
selective permeability that allows certain ions to cross the membrane and with different
speed. At rest there is predomination of sodium ions at the surface and potassium ions in
the cross section. Sodium ions diffuse from the surface to the cross section( following the
concentration gradients, from higher to lower concentration) while potassium ions diffuse
from the cross section to the surface(higher to lower concentrations). But the diffusion
potassium ions is faster than sodium ions. This diffusion with different speed creates resting
potential.

Question 3

How is Resting Potential Maintained?

Answer 3

if diffusion continues for a while then equilibrium takes
place , but in living cells this never to happen, this is because of the mechanism that pumps
Na + ions from inside to outside(against the concentration gradient) and K + ions from outside
to inside. This active transport against concentration gradient requires energy in the form of
ATP(adenosine triphosphate). They are transported by transporter proteins (Na + / K + ATP ase
active pump. This pump has conformation X or Y. conformation X fits for K + and
conformation Y fits for Na + . ATP is needed to change X into Y and enzyme is needed to
change Y into X.