 Dear students, in this module, we shall discuss the voltage-gated potassium channels in detail. The potassium channels are slightly smaller in size than the sodium channels. The potassium channel gates are on the intracellular ends. The opening of these gates results in an outflow of potassium ions. Potassium ions come out of the cells due to the opening of the channels. These channels remain closed in the resting neuron and they open during the action potential when the inside of the membrane has become positively charged due to depolarization, that is, at the peak phase of action potential. Dear students, the potassium channels are known as delayed rectifiers. They respond more slowly to depolarization as compared to the fast-acting sodium channels. They start opening when the action potential has reached its peak phase. That is why they are called delayed rectifiers. The opening of potassium channels results in an increase in the conductance of potassium across the membrane. The potassium conductance begins to increase when action potential is near its peak and it remains high in the falling phase. The outward flow of potassium ions results in decreasing the membrane potential to potassium equilibrium potential, that is, about minus 90 millivolts. Dear students, the actual role of potassium channels is not to generate action potential but actually they are involved in the acceleration of membrane repolarization that is a step towards ending the action potential. Activation of more potassium channel in a membrane means that action potential will be shortened. That is why more potassium channels open when membrane is producing action potentials of short duration. This helps the neurons to generate action potentials at higher frequency. Dear students, the number of potassium channels in different types of neurons also varies. They occur abundantly in those membranes which are involved in generating action potentials of shorter duration while they are present in lower number in the neurons that generate action potentials of longer duration. They are even absent in some myelinated mammalian neurons that produce action potentials of very long duration.