Drag the labels onto the flowchart to indicate the sequence of events that occurs in the presynaptic cell (orange background) and the postsynaptic cell (blue background) after an action potential reaches a chemical synapse. the presynaptic cell (the sending neuron) to its synaptic terminal(s) Drag the labels onto the flowchart to indicate the sequence of events that occurs in the presynaptic cell (orange background) and the postsyna potential reaches a chemical synapse. neurotransmitter released into synaptic cleft action potential enters the presynaptic membrane a ) Ca2+ channels in presynaptic membrane open briefly neurotransmitter degraded or removed from cleft; ligand- gated ion channels close neurotransmitter binds to ligand-gated ion channels in postsynaptic membrane; channels open Ca2+ ions enter presynaptic cell neurotransmitter- containing vesicles fuse with presynaptic membrane