Science 48

Neurons are specialized cells that comprise the nervous system. They are capable of sending signals to and from the brain by using charge gradients. These differences in charge are created by pumps that move ions (charged molecules) of sodium (Na) and potassium (K), both of which carry a positive charge.

A scientist studying the conduction of neuronal signals determines the following:

1. When a neuron is not conducting a signal, there is a positive charge outside the cell and a negative charge in the cell (measured to be -65 mV). He calls this Resting Potential.

2. When a neuron is conducting a signal, the charges reverse. He calls this Action Potential and determines that the new charge inside the neuron is +50 mV.

3. A signal can not be sent until a neuron reestablishes its original charged state. The time for which it takes a neuron to return to Resting Potential is its Refractory Period.