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) Definition of synapse: A junctional connection between two neurons,across which a signal can pass Pre-synaptic neuron:Where a neurotransmitter is synthesized,stored and released upon cell activation. Post-synaptic neuron or effector cell:Where neurotransmitter is detected and its action translated into cellular activities. 33 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 Pre-synaptic nerve cell Post-synaptic nerve cell Synaptic cleft Ca2+ Na+ Precursors (choline/tyrosine) Definition of synapse: A junctional connection between two neurons, across which a signal can pass Precursor Neurotransmitter Storage Release Recognition by receptors Metabolic disposition Pre-synaptic neuron: Where a neurotransmitter is synthesized, stored and released upon cell activation. Post-synaptic neuron or effector cell: Where neurotransmitter is detected and its action translated into cellular activities