Nerve Impulses Resting Potentials Electrical potential across plasma

Nerve Impulses

Resting Potentials • Electrical potential across plasma membrane of a cell • Not conducting impulse

Action Potentials • Reversal & restoration of electrical potential across the plasma memebrane of a cell • Electrical impulse passes along it

Stages in Passage of Nerve Impulse • Diffusion of sodium ions • Local currents reduce resting potential

Depolarization • Sodium channels open • Sodium ions diffuse into neuron

Repolarization • Potassium channels open after short delay • Potassium ions diffuse out of neuron

Ion Movements • Concentration gradient of Na & K are restored • Restores resting potential • Ready to conduct next nerve impulse

Page Number & Vocabulary Study Guide: p. 53 Course Companion: p. 240 -243 HL Pearson: p. 176 -178 Resting Potential: electrical potential across plasma membrane of cell that is not conducting impulse • Action Potential: reversal and restoration of electrical potential across plasma membrane of cell, as electrical impulse passes along it • •

Vocabulary • Depolarization: change in cell’s membrane potential, making more positive • Repolarization: change in membrane potential that returns membrane potential to negative value after depolarization phase of action potential has just previously changed membrane potential to positive value