Neuron resting and action potential

BiologyHuman & Animal PhysiologyAges 16–17

A cross-section of the neuron membrane shows Na⁺ and K⁺ ions on both sides, Na⁺ channels, K⁺ channels and the Na⁺/K⁺ pump; click Stimulate (or tap the axon) to depolarize the membrane. A subthreshold stimulus only causes a small graded change that fades out; once the −55 mV threshold is reached, Na⁺ channels open in a rush, the potential spikes to +30 mV, then K⁺ channels open to repolarize and hyperpolarize back toward −70 mV. The membrane potential vs. time (ms) graph scrolls continuously, with the refractory period marked.