The ________ at the end of the axon branches contain small sacs called vesicles, which produce the neurotransmitters that are needed to allow impulse transmission to continue to the postsynaptic structures.

Neurotransmitters

Chemical substances released by neurons to transmit signals across a synapse to another neuron, muscle cell, or gland cell.

Postsynaptic Structures

Components of a neuron located after the synapse that receive and process signals from presynaptic neurons.

Vesicles

Small sacs within the synaptic knobs that contain chemicals called neurotransmitters.