Resting Membrane Potential and Action Potentials in Neurons

Typical resting membrane potential

-70 mV

Ion with highest permeability at rest in neurons

Potassium (K⁺)

Equation to calculate equilibrium potential for a single ion

Nernst Equation

Determines ion movement across the membrane

Electrochemical gradient

Equation that calculates membrane potential considering multiple ions

Goldman-Hodgkin-Katz equation

Typical permeability ratio of Na⁺ to K⁺ in neurons

P_Na⁺ / P_K⁺ = 0.01

Function of the Na⁺/K⁺ ATPase pump

Maintains ion gradients and contributes to the resting membrane potential

Effect of ouabain on Na⁺/K⁺ ATPase

The membrane depolarizes

Ion influx responsible for rising phase of action potential

Sodium (Na⁺)

Trigger for opening of voltage-gated sodium channels

Small depolarization past threshold

What Hodgkin & Katz's experiment showed

Sodium (Na⁺) is essential for the amplitude of the action potential