Synapses and the Role of Neurotransmitters Flashcards
What is the relative abundance of glia with respect to neurones?
Glia are 10-50x more abundant than neurones.
List 5 functions of glia.
1 - Guiding connecting.
2 - Physical support.
3 - Metabolic support.
4 - Electrical insulation.
5 - Signalling.
What is the function of the axon hillock?
Action potential generation.
What are the two types of synapse in the CNS?
1 - Electrical synapses (gap junctions).
2 - Chemical synapses.
List 2 differences between electrical and chemical synapses.
1 - Electrical synapses are faster than chemical synapses.
2 - Electrical synapses allow for bi-directional communication whereas chemical synapses only allow for uni-directional communication.
Where are gap junctions found?
1 - Between glia and neurones.
2 - Between glia and other glia.
3 - In cardiac myocytes.
What 2 processes terminate a signal at a synapse?
1 - Enzymatic breakdown of receptor-neurotransmitter complexes.
2 - Reuptake of the neurotransmitter.
What is the major excitatory neurotransmitter?
Glutamate.
What is the major inhibitory neurotransmitter?
GABA.
List 4 major chemical groups of neurotransmitters.
1 - Amino acids.
2 - Monoamines.
3 - Acetylcholine.
4 - Neuroactive peptides.
List 3 amino acid neurotransmitters.
Which are excitatory and which are inhibitory?
1 - Glutamate (excitatory).
2 - GABA (inhibitory).
3 - Glycine (inhibitory).
List 4 monoamine neurotransmitters.
1 - Noradrenaline.
2 - Adrenaline.
3 - Dopamine.
4 - Serotonin.
List 2 types of neuroactive peptide.
1 - Opioid peptides.
2 - Tachykinins.
What are the two types of receptor signalling mechanisms in chemical synapses?
1 - Ionotropic.
2 - Metabotropic.
List the differences between the effects of ionotropic and metabotropic receptor signalling mechanisms.
1 - Ionotropic receptors have faster transmission than metabotropic receptors.
2 - Ionotropic receptors have shorter lasting effects than metabotropic receptors.
List 4 excitatory ionotropic receptors.
1 - Nicotinic ACh receptor.
Some subtypes of glutamate receptor:
2 - AMPA receptor.
3 - NMDA receptor.
4 - Kainate receptor.
What is the result of excitatory ionotropic receptor activation?
- Membrane depolarisation by Na+ influx.
- A small excitatory post-synaptic potential (EPSP).
Give an example of an inhibitory ionotropic receptor.
The GABA-A receptor is an inhibitory ionotropic receptor.
What is the result of inhibitory ionotropic receptor activation?
- Membrane hyperpolarisation (more negative) by Cl- influx.
- A small inhibitory post-synaptic potential (IPSP).
What is the difference between GABA-A and GABA-B receptors?
GABA-A receptors are ionotropic whereas GABA-B receptors are metabotropic.
List 3 metabotropic receptors.
1 - Muscarinic ACh receptors.
2 - GABA-B receptors.
3 - Monoamine receptors (all are metabotropic with one exception).
*Excitatory or inhibitory depending on subtype!
Define spatial summation.
Spatial summation is the summation of postsynaptic potentials generated at separate synapses at the soma of a neurone.
Define temporal summation.
Temporal summation is the summation of postsynaptic potentials generated at the same synapse at the soma of a neurone when the incoming action potentials are generated in rapid succession.
How does the mechanism of ionotropic receptors differ from that of a metabotropic receptor?
- An ionotropic receptor functions by directly opening an ion channel.
- A metabotropic receptor functions by triggering effector systems through GPCRs.
