Neurotransmitters

Illustration showing the action of neurotransmitters such as serotonin and noradrenaline in the synaptic cleft. Vesicles containing the neurotransmitter (green) move towrds the pre-synaptic membrance where they fuse with the cell membrane, releasing their contents into the synaptic cleft. The neurotransmmitter molecules act on the post-synaptic cell by binding to specific receptors on the cell surface (purple). They can also be taken back up by the presynaptic cell via other receptors (orange) for re-use.