I'm not sure if this question is talking about neurons, but if it is... depolarization in a neuron leads to an "action potential."
Saturated fatty acids are 'saturated' with hydrogen meaning they contain the maximum number of hydrogen. This causes them to be straight on the molecular level, allowing them to be packed close together other saturated fatty acids. Thus, they tend to be solids at room temperature. Examples of saturated fats are butter and the solid white fat you see on raw meat.
