Potassium ions have a positive charge, so their absence restores the negative charge inside the axon. The neuron is again polarized and at rest, waiting to fire another impulse. Neurotransmitters bind to receptors Neurotransmitters float across the synapse until they hit the dendrites of the next neuron. On each dendrite, neurotransmitters find molecules that are set to receive them. These molecules are called receptors .
Neurotransmitters bind to receptors.
Each receptor accepts only certain neurotransmitters, much like a lock accepts only a certain key. After binding is done, receptors let go of the neurotransmitters. At that point, several things can happen. Some neurotransmitters are destroyed by enzymes. In other cases, proteins transport neurotransmitters back to the axon from which they originally came, a process called reuptake .