The outside of a neuron has more sodium ions while at resting state. When a electrical signal is going to pass through, the sodium channels open up first and the positive sodium ions rush inward making the inner side more positive. This is called action potential.
There is layer of fatty substances called as Myelin Sheath over the course of axons. It helps the electrical signal to be transmitted with a fast pace and efficiently over the course.
Food insecurity, because you are only lacking safe and nutritious food. It would be famine if you had no food whatsoever, and it would be a food shortage if you were lacking a small amount of ALL food