synaptic transmission Flashcards
4 types of neural communcation
1.electriclal synapse- gap junction- ion/ small molecule exchange
2. chemical synapse- mediated by neurotransmitter- naming depends on target cell
3. neuromuscular junction (neuron with muscle)
4. neuroendocrine system- neuron with bloodstream to organ
majority of neural communcation
occurs via chemical synapse
4 types of transmitters
- conventional- small molecule stored in vesicles
- neuropeptide stored in vesicles
- gas no storage, on demand, cross bilayer
- lipid no storage, on demand, cross bilayer
examples of conventional neurotransmitters
amino acid (glutamate, gaba)
monoamines (NE, DA, 5HT)
acetylcholine
examples of neuropeptide neurotransmitters
substance p and nasopressin
examples of gas neurotransmitters
nitric oxide
carbon dioxide
examples of lipid neurotransmitters
endocannabinoid
prtraglandin
common types of neurotransmitters
small molecule and neuropeptide
can neurons release multiple neurotransmitters
yes most can
functionally affects neurodegenerative deseases bc both main and co transmitters are lost
what happens when AP arrives to end of axon
Ca infux in and neurotrnasmitter is released
3 fates of neurotransmitter
- uptake
- degradation
- diffusion
what is common to every synapse
- action potential
- ca influx
- exocytosis
what is specific to each neurotransmitter
- uptake
- synthesis
- degradation
- receptor activation
ionotropic receptor
fast (miliseconds)
excitatory or inhibitory depending on ions
mediated by ion channels
G protein couples receptor (metabotropic)
long lasting (second to min)
excitatory or inibitory depending on signaling pathway
mediated by secondary messengers regulating downstream effectors (ion channels and gene/protein expression)
GPCR diveristy
very diverse
common drug targers
GPCR
do all receptors have the same response to the same neurotransmitter
no
differences in different receptors
- different kinetics
- be linked to different signalling mechanisms
- be expressed at different subcellular locations
- be modulated or regulated differently
EPSP
Excitatory postsynaptic potential
IPSP
inhibitory postsynaptic potential
what are EPSP + IPSP due to
activation of ionotropic receptors or activation/ inhibition of ion channels via GPCRs
what kind of potentials are post synaptic potential
graded and not regenerative aka they diminish
temporal summation
single synapse activating multiple times at quick succession
spatial summationn
occurs when multiple synapses activate simultaneously. can occur between excitatory and inhibitory synapses
two types of synaptic integration
temporal and spatial summation
what causes synaptic strength to change
neuromodulators and drugs
synaptic modulation
leads to synaptic facilitation or synaptic inhibition
is synaptic strength constant
no
what are the targets of synaptic modulation
any step of neurotransmission.
psychoactive substance or drug target
synaptic plasticity
can yield synaptic potentiation or synaptic depression
variation of synaptic plasticity
can vary based on
different synapses
different physiological states, pathological states
firing pattern of presynaptic neuron
difference between synaptic modulation and plasticity
modulation: neuromodulator dependant
endogenous modulators: neurotransmitters, hormones, cytokines
exogenous modulators: psychoactive drugs
plasticity
plasticity: synaptic activity dependant
short term or long term (hours to years)
at what level does summation occur
at cell body
at what level does synaptic modulation and plasticity occur
at synapses
