Neurotransmitter: A chemical that transmits signals from one neuron to another or from a neuron to an effector cell. Chemical (intracellular messengers) Electrical Stimulation Chemical Physiological (impulse) (neurotransmitter) functions Electrical (membrane ion channels)Electrical Stimulation (impulse) Chemical (neurotransmitter) Neurotransmitter: A chemical that transmits signals from one neuron to another or from a neuron to an effector cell. Chemical (intracellular messengers) Electrical (membrane ion channels) Physiological functions