Covers synapses as junctions between neurones, naming the pre- and postsynaptic membranes and the cleft, then how neurotransmitters are synthesised and stored, with acetylcholine and neuropeptides contrasted. It compares electrical and chemical synapses, listing their structure, speed, and connexin-related disorders, and sets out the chemical transmission steps from release to removal. It closes with excitatory and inhibitory effects, and classical versus neuromodulatory signalling.
Topic 8 of 104 in the MU Sofia syllabus for Physiology (Medicine, Year 2). The free AceMed note covers it in 2 sections, about 943 words (7 min of reading), with 12 flashcards.
In this note
Introduction
Synthesis and Storage of Neurotransmitters
Introduction
Synapse is the junction between two cells where communication between the cells takes place.
Each synapse consists of the:
Presynaptic membrane – membrane of the terminal button of the nerve fiber
Postsynaptic membrane – membrane of the target cell
Synaptic cleft – a gap between the presynaptic and postsynaptic membranes
A synapse is a gap that is present between two neurones. Action potentials are propagated across the synapse by synaptic transmission, also known as neurotransmission. The neurone that sends the signal is the presynaptic neurone, whilst the postsynaptic neurone receives the signal.
Neurotransmission starts with the release of a readily available neurotransmitter from the presynaptic neurone, followed by its diffusion and binding to the postsynaptic receptors. Then the postsynaptic cell responds according to the neurotransmitter. Following this, the neurotransmitter is removed or deactivated, allowing the entire cycle to occur again.
