Resting Membrane potentialResting Membrane potential At rest, all cells are negatively charged On inside with respect to charge on exterior
Resting Membrane PotentialResting Membrane Potential The negative charge is the result of an unequal distribution of charged ions across the cell membrane
Resting Membrane PotentialResting Membrane Potential A neuron is said to be polarized This electrical charge difference is called the resting membrane potential potential is just another way of saying “charge difference”
Resting Membrane PotentialResting Membrane Potential How is this resting potential of neurons maintained? Sodium/potassium pumps Use energy from ATP to maintain intra/extracellular concentrations by pumping sodium out and potassium into the cell.
Resting Membrane PotentialResting Membrane Potential Pumps not only maintain concentration gradients to maintain resting membrane potential, The actually generate it by exchanging 3 sodium ions for every 2 potassium ions
Action PotentialsAction Potentials How and when is a neural message generated? A stimulus of significant strength reaches the neuron and opens sodium gates This allows sodium ions to diffuse into the neuron, making the inside more and more positive
Action PotentialsAction Potentials When this depolarization reaches a critical value called “threshold”… Sodium gates open wide and an action potential is formed.