Neuro Refractory Period

The action potential is the signal that travels down the axon when a neuron is transmitting information. To understand the action potential, which is essentially the flow of ions in and out of the neuron that differ from the normal flow, one must understand the relation of ions, especially sodium and potassium, with the neuron. Neurons are covered by membranes that regulate the inflow and outflow of chemicals, and certain chemicals, like sodium and potassium can only flow in and out via channels along the membrane. At rest, the membrane maintains a certain polarization between the inside and outside of the neuron, with the inside being a little more negatively charged than the outside, at a resting membrane potential of -70 mV. When a neuron

The refractory period, though very small, is divided into two parts, the absolute and relative periods. In the absolute refractory period, no action potentials can occur, no matter what the stimulation. In the relative refractory period, an action potential can happen if a stimulus stronger than the normal one occurs. When the Na+ channels refract, the K+ channels, open due to the depolarization, allow potassium to leave the cell. Because the inside of the cell has become more positive due to the influx of sodium, the outside is relatively more negative, attracting the potassium. Thus the gradients push potassium ions out of the axon, helping the membrane potential go back to its value at rest. As the resting potential goes back to its original value, it is temporarily hyperpolarized due to the potassium ions just leaving and causing the charge between the inside and outside to differ more than resting potential (the inside is seemingly more negative in comparison to the outside).The resting potential is restored after the potassium ions diffuse away, even though the distributions of Na+ and K+ differ from what they were before the process. This is where the sodium-potassium pump comes back to reestablish the concentrations of the ions before the action