Sound waves need to travel through a medium such as a solid, liquid, or gas. The sound waves move through each of these mediums by vibrating the molecules in the matter. The molecules in solids are packed very tightly. Liquids are not packed as tightly as solids. And gases are very loosely packed.
When chemical communication at a synapse is terminated by the recapture of neurotransmitter molecules by the presynaptic neuron, we refer to the process as <u>Reuptake.</u>
