Describing the action potential and its phases

An action potential is caused by either threshold or suprathreshold stimuli upon a neuron. It consists of four phases; hypopolarization, depolarization, overshoot, and repolarization. An action potential propagates along the cell membrane of an axon until it reaches the terminal button.

supercell thunderstorms are perhaps the most violent of all thunderstorm types, and are capable of producing damaging winds, large hail, and weak-to-violent tornadoes

igneous rocks which formed by the crystallization of magma at the surface of the earth called extrusive rocks. they are characterized by fine-grained textures because the rapid cooling at or near the surface did not provide enough time for large crystals to grow.