Outline how the first neurone communicates with the second neurone at a synapse.

The neurotransmitter e.g. Acetylcholine is excocytosed at the presynaptic membrane, the neurotransmitter diffuses across the synaptic cleft, down its concentration gradient, then attaching to complementary receptors on the post-synaptic membrane. Finally, the neurotransmitter is broken down at the synaptic cleft by enzymes e.g. acetylcholinesterase.