Factors influencing the outcome of neurotransmission Flashcards
Excitatory neurotransmitter
Glutamate (upwards/positive inflection)
Inhibitory neurotransmitter
GABA (downwards/negative inflection)
What may be the cause of both a fast and slow AP release in response to a single synaptic event
2 different ionotropic receptor types responding to single event
The influence of a synapse is dependent on…
- the distance the current has to travel to the neurones trigger zone
- mbp has to be more positive than the threshold
- the closer an event is to an axon hillock, the more likely the probability of AP conversion
Define quanta
- the release of a neurotransmitter from a single vesicle
- the number of quanta released varies with the stimulus
- the number of quanta released by stimulation of the neuron can vary for every neuron for every stimulus
Strategies to increase quantal release
- extensive innervation (purkinje cell / inhibitory basket cell)
- mega humongous presynapse (calyx of held synapse)
Purkinje cell - Inferior Olivary Neuron Synapse
- example of extensive innervation
The inhibitory basket cell
- example of extensive innervation
The Clayx of Held synapse
- an example of mega humongous presynapse
- strategy to increase quantal release
Activation of excitatory input
produces a large EPSP at trigger zone (cation selective channels Na+ and K+)
Activation of inhibitory input
produces a large IPSP at initial segment (opens Cl- channels)
Simultaneous activation of excitatory and inhibitory inputs
reduced EPSP (inhibitory input shunts excitatory response) -> suppression of some APs, resulting in distinct pattern of discharge
Spatial summation
EPSPs and IPSPs are spatially distributed but timed together
Temporal summation
EPSPs occur in temporal sequence such that threshold is triggered
