Lecture 4: Synaptic Transmission Flashcards
When ions/small molecules exchange between cells
Electrical synapse
What is mediated by neurotransmitters
Chemical synapse
Majority of neuronal communication occurs via ______
Chemical synapse
Gaseous and lipid transmitters are less common, can easily cross ______ therefore not stores in synaptic vesicles
Lipid bilayer
Most if not all neurons can release multiple ____
Neurotranmitters
In neurodegenerative diseases, not only the main
neurotransmitter but also_____ are lost.
Co-transmitters
Axon terminal express ___ , ___, ____
Na+
K+
Ca++
Neurotransmission:
Transmitter release:
1. _____ arrives
2. ___ influx
3. ____
Action potential
Ca2+
Exocytosis
____ Receptor
Time course -fast
Cellular response - excitatory or inhibitory
Mediator of cellular response - receptors = ion channels
Ionotropic
_____ receptor
Time course : long lasting
Cellular response: excitatory or inhibitory (depends
on signaling pathway involved)
Mediator of cellular response: second messenger regulates downstream effectors
G protein-coupled (GPCR)
IONOTROPIC RECEPTOR
Time course :____
Cellular response: ______
Mediator of cellular response: ___=___
Fast
Excitatory or inhibitory
Receptors = ion channels
___ ‘s are very diverse
- one of the most common drug targets
GPCR
Some neurotransmitters activate both ___ and ___
Ionotropioc receptor and GPCR
Neuroleptics receptors are ____
GPCR
Depending on the receptor the same transmitter can induce different ____ response
Postsynaptic
Different receptors can:
1. Have different ___
2. Be linked to different ___ mechanisms
3. Be expressed at different ___ mechanisms
4. Can be regulated___
Kinetics
Signalling
Sub cellular
Differentially
What triggers neurotransmitter release?
Calcium
How is neurotransmission terminated (3 answers)?
Uptake, degradation, diffusion
Which processes of neurotransmission are specific to a
neurotransmitter?
Synthesis, receptors, reuptake, degradation
Which steps of neurotransmission are common to chemical synapses?
Action potential, Ca++ influx to axon terminal, exocytosis
What are the two major classes of receptors involved in neurotransmission? Main differences?
• Ionotropic receptors: fast, mediated by ionic current
• metabotropic (G protein-coupled) receptors: slow & long lasting, mediated
by second messengers
What is the physiological significance of receptor diversity for a given
transmitter?
Different receptors can mediate distinct responses (excitatory or inhibitory,
time course, subcellular localization) • Different receptors can be regulated differently
Change in postsynaptic membrane potential as a result of ____
Neurotransmission
EPSP and IPSP are due to
• activation of ______ or
• activation/ inhibition of _____ via GPCRs
Ionotropic receptors
Ion channels
Postsynaptic potential
• Initially starts locally at the synapse and propagates along the _____
• Postsynaptic potentials are ____ potentials (amplitude can vary)
• The ____ diminishes with distance traveled (not regenerative)
Cell membrane
Graded
Amplitude
Individual postsynaptic potential may be too small to_____ an action potential, but multiple postsynaptic can add up to become larger
Initiate
_________ of postsynaptic potential can occur when multiple synapses activate simultaneously
Special summation
A single synapse activating multiple times in quick succession can result in temporal summation of postsynaptic potential
Temporal summation
Synaptic integration
1. Three excitatory neurons fire, their grades potentials separately are all below ____
2. ______ arrive at trigger zone together and sum to create asuprathreshold signal
3. An ___ is generates
Threshold
Graded potentials
Action potential
• Spatial summation can
occur between _____ and ____ synapses
• Inhibitory signal dampens
_____ signal
Excitatory and inhibitory
Excitatory
_______= magnitude of postsynaptic potential
• Synaptic strength is not
_____. It can be modulated
Synaptic strength
Constant
Any step of neurotransmission can be a target of synaptic modulation
• ________ substance
• ______ target
Psychoactive
Drug
Earlier synaptic activity altering later synaptic ______
Responses
Synaptic ____: neuromodulator-dependent
Modulation
Synaptic ____: synaptic activity-dependent
Plasticity
Virtually every synapse in the nervous system can undergo synaptic _____ and _____
modulation
Plasticity
At synapses = synaptic _____ or synaptic ___
At cell body = ____ (synaptic integration)
Modulation
Plasticity
Summation
- _______________
• Physical innervation (hard-wired)
• Rapid transmission of signals
• Action potential • Synaptic transmission
Rapid and specific propagation of signal
- _________< _____
• Summation
• Synaptic modulation
• Synaptic plasticity
• Convergence, divergence
Integration commutation
- _______
• Synaptic plasticity
Availability
What are the differences between action potential and synaptic
potential?
• Action potentials are all or none, regenerate while propagating along
the axon
• Synaptic potentials are graded, decays with time and distance traveled
How can small postsynaptic potentials induce action potentials?
Summation
What are the similarity and difference between synaptic modulation
and synaptic plasticity?
• Similarity: synaptic strength changes
• Difference: synaptic modulation is typically induced by neuromodulators (endogenous modulators, drugs etc); synaptic plasticity is induced by synaptic activity (previous synaptic activity altering future synaptic strength)
