Review of Synaptic Transmission Flashcards
Chemical Synapse Characteristics
- Release neurotransmitters which activate receptors. 2. Are the majority of synapses in mammalian nervous system 3. Can be axo-dendritic, axosomatic, axo-axonal, or dendrodendritic. 4. Used to transfer a signal.
Electrical Synapse Characteristics
- Direct electrical connection via gap junctions. 2. Rare. 3. Dendro-dendritic (mostly). 4. Used to share a signal.
Define gap junctions.
Electrical synapses are direct connections between two neurons that allow for ions to flow unimpeded between the two cells.
Explain the homeostatic regulation of post-synaptic receptors
If the cell becomes to active, it will remove excitatory receptors from the synapse. If the cell gets too quiet, more excitatory receptors will be added.
Factors affecting quantal content
- Drugs that increase or reduce docking or fusion of vesicles (eg. Botox). 2. Synapses onto the presynaptic terminal (eg. Opioids). 3. Short-term overuse of the presynaptic terminal (eg. Running out of vesicles).
Factors affecting quantal size
- Drugs that affect loading of vesicles. 2. Drugs that affect reuptake/breakdown of neurotransmitter. 3. Plasticity at the post-synaptic neuron (eg. Receptor up or down regulation.
What breaks down acetylcholine and where is it done?
Acetylcholinesterase and in the synapse
How is glutamate recovered?
Taken up by the pre-synaptic neuron and astrocytes
Transmitters with excitatory receptors?
Glutamate and acetylcholine
Transmitters with inhibitory receptors?
GABA and glycine
What is the purpose of the astrocytes?
They provide metabolic support and may be able to modulate synaptic activity.
Describe what happens in the formation of the SNARE complex
- Vesicle docks
- Entering Ca2+ binds to synaptotagmin
- SNARE complex forms to pull membranes together
- CA2+-bound synaptotagmin catalyzes membrane fusion by binding SNAREs and plasma membrane.
