Transmission + NTs Flashcards
How many connexin subunits make up 1 connexon (hemichannel)?
6
Gap junctions are formed from 2 ______ between two neurones?
Hemichannels (connexon)
Distance across an electrical synapse is?
Distance across chemical synapse is?
3.5nm
30-50nm
Electrical synapses function by what agent of transmission?
Ionic current
Synaptic delay:
- Electrical?
- Chemical?
- none
- 1-5 ms (min 0.3ms)
Are chemical/electrical synapses unidirectional or bidirectional?
Chemical: unidirectional
Electrical: bidirectional
Peptide NTs are synthesised in ___ and stored in___?
Amine and AA NTs are synthesised in ___ and stored in___?
Cell body, large dense core vesicles (90-250nm)
Synaptic terminal, small clear vesicles (40-60nm)
A single neurone can produce and release >1 NT. This is called?
Co-existence / co-transmission
Which vesicle bound SNARE protein binds to SNAP-25 causing vesicle docking/priming?
Synaptobrevin
What is synaptotagmin and what role does it have?
- Vesicle bound SNARE protein
- Ca sensor
- Involved in fusion of vesicle to montane
What is an MEPP and an EPP?
(Miniature) end plate potential
EPP = multiples of MEPPs (single vesicle release)
EPP is action potential dependent
An IPSP is due to influx of which ion?
Cl-
Which type of synapse is more common, electrical or chemical?
Chemical
Glutamate is removed from synapse by?
EAATs (excitatory amino acid transporters)
- in glial cells and presynaptic terminal
Glutamate taken up into glial cells is converted to _____ by ________?
Glutamine
Glutamine synthase
Precursor for glutamate is___?
Converted to glutamate by what enzyme?
GLUTAMINE
Glutaminase
Too much glutamate can be toxic to neurones. This is called____? And can cause?
Excitotoxicity
Epilepsy, ischemia, hypoglycemia
GABA is synthesised from _____ by ______?
Glutamate
Glutamic acid decarboxylase (an co-factor pyridoxal phosphate, vit B6 derivative)
GABA is removed from synapse and taken up into glia and neurones by____?
GABA transporters
Na dependent co-transporters
Effects of benzodiazepines, barbiturates and alcohol work by _______ of GABA signalling?
Potentiation
Co-release of small molecule and peptide NTs occurs at what kind of stimulation?
High frequency stimulation
NB: only small molecule NTs released at low freq stimulus
How many transmembrane domains do subunits of IONOTROPIC receptors have?
4 transmembrane helices
Or 3 + pore loop
The nicotinic Ach R is permeable to which ions,?
Na+
K+
Sometimes Ca2+
Glutamate IONOTROPIC receptors have how many subunits?
4 (tetramer)
