Synaptic Transmission Flashcards
What is the neurone distance in electrical transmission?
3.5nm
Electrical transmission involves what structures?
Gap junctions
Give the structure of gap junctions.
Connected by hemichannel connexons, made up of 6 connexin subunits
What aspects can modulate gap junction alterations?
pH, neurotransmitter, and intracellular calcium
Electrical transmission allows synchronisation, how does this aid and hinder transmission?
Allows neurones to act in the same way. But over synchronisation can cause seizures
Chemical transmission involves the crossing of a synapse that is how large?
30-50nm
How long does it take for the transmission to take place?
0.3-5ms
What is the chemical involved in transmission?
Neurotransmitter
Which neurotransmitters are synthesised in the axon terminal?
Amino acid and amine NTs
Where are peptide hormones produced?
In the cell body, via ribosomes on RER
How do peptide hormones travel from the cell body to the axon terminal?
In secretory granules via axoplasmic transport
How are neurotransmitters stored in the axon terminal?
In secretory granules near the active zones
What triggers the release of neurotransmitters from the axon terminals?
A rise in intracellular calcium due to influx
How are neurotransmitter removed from the synapse?
Reuptaken, enzymatically broken down, or diffused away
Give 5 examples if amine neurotransmitters.
Dopamine, noradrenaline, adrenaline, histamine and serotonin
Which neurotransmitters are considered amino acids?
GABA, glutamate and glycine
For a messenger to be considered a neurotransmitter is must posses what 5 proportions?
Synthesised in the neurone, present in the presynaptic terminal, exert effect on postsynaptic neurone, produce the same effect exogenously and have a mechanism of removal
What are the two types of synaptic vesicles called and how do they differ?
Small clear vesicles (40-60nm) and large dense core vesicles (90-250nm)
What is it described as when a neurone contains both types of synaptic vesicle?
Co-existence
What does the term co-transmission mean?
A neurone that can synthesise and release more than one transmitter
Where are voltage gated calcium channels concentrated in synaptic terminals?
Near the active zones
How do synaptic vesicles fuse to the membrane for exocytosis?
Via SNARE proteins
Which SNARE proteins are membrane bound?
SNAP-25 and syntaxin
Which SNARE protein does synaptobrevin bind to?
SNAP-25
Which SNARE protein does synaptotagmin bind to, and what is it’s secondary function?
Syntaxin and it is a calcium sensor
What type of potential can occur without the arrival of an action potential?
A miniature end plate potential (MEPP)
What does quanta release mean?
It is the spontaneous release of one synaptic vesicle due to a MEPP
What are the two types of receptors on the postsynaptic membrane?
Metabotropic (GPCR) and ionotropic (LGIC)
