AP PSYCHOLOGY

Detailed explanation-1: -The fluid inside a neuron is separated from that outside by a polarized cell membrane that contains electrically charged particles known as ions.

Detailed explanation-2: -The movement of a signal through the neuron and its axon is all about ions. An ion is a charged particle, such as Na+, the sodium ion.

Detailed explanation-3: -At rest, there are relatively more sodium ions outside the neuron and more potassium ions inside that neuron.

Detailed explanation-4: -The inside of the cell has a low concentration of sodium ions, and the outside of the cell has a higher concentration of sodium ions. Each sodium ion is counterbalanced by an anion that is found on the same side of the membrane as the sodium ion.