Lecture 3a-neurotransmission Flashcards
two types of synapses
electrical synapses
chemical synapses
electrical synapses are connected by?
connexons
three types of chemical CNS synapses
axodendritic
axoaxonic
axosomatic
axoaxonic connect what to what?
axon to axon which connects to a third axon cell body
axoaxonic synapses can act as _____
inhibitor/ activators
relationship between amines and neuropeptides
act as neuromodulators
3 criteria to define an NT
- NT is synthesized and stored in pre-synaptic terminal
- NT released in response to presynaptic depolarization in Ca++ dependent manner
- if NT is experimentally applied must have the SAME response as it would if it was released from a pre-synaptic terminal and up-taken by a post-synaptic
_______ are synthesized in the presynaptic terminal
amines + amino acids
______ are synthesized in the RER
neuropeptides
________ move via slow axonal transport
amines + amino acids
neuropeptides use vesicles for transport t/f?
false-use secretory granules
amino acids/amines move via slow axonal transport to the terminal. T/F?
false- neuropeptides do this
what type NT is degraded after release
neuropeptides
what type of NT is reuptaken into the next terminal after release
amino acids + amines
two methods for localizing NTs
ask yourself too, what they do/how used
in situ hybridization
immunoctyo-chemistry
two ways a NT can be dealt with after its released into synaptic cleft
reuptake
enzymatic destruction
2 types of postsynaptic receptors
ionotropic receptors
metabotropic receptors
what happens if NT isn’t cleared out of synaptic cleft
synapse might become desensitized to NT and stop responding to it
each receptor binds a specific NT and each NT may bind to only one specific receptor. T/F?
false- NT mau bind to a number of different receptors
i.e Ach-gate Na+ channel vs. Ach G-protein coupled K+ channel
what does a receptor agonist do
mimics the effects of a NT
what does a receptor antagonist do
prevents NT from binding
nicotine is a (a) in relation to Ach
agonist
curare is a (a) in relation to ach
antagonist
nicotine receptors are in ____muscle?
skeletal muscle
muscarine receptors are in ____muscle ?
heart
muscarine is a ?
agonist
atropine is a?
antagonist
what are the two agonists for the Ach receptor
nicotine
muscarine
what are the two antagonist for the ACh receptor
curare
atropine
what three agonist can replace glutamate
and on which receptors
NMDA (nmda receptor)
kainate (kainate receptor)
AMPA (ampa receptor)
what type of receptors does NE bind to
alpha and beta
what receptors does GABA bind to
GABAa and GABAb
3 ways to study receptors
1) neuro-pharmacoligcal anaylsis - uses agonist + antagonists
2) ligand-binding methods- use radio labeled ligands
3) molecular analysis - study protein molecules that make up receptors
what ion (a) binds to which receptors (b) to cause what effect (c) in EPSP
a) Na+
b) Ach or glutamate-gated ion channels
c) depol
what ion (a) binds to which receptors (b) to cause what effect (c) in IPSP
a) Cl-
b) glycine or GABA-gated ion channels
c) hyperpol
where is the [ ] of Cl- greater, inside or outside cell
outside cell
draw EPSP and IPSP graphs
see notes
when internal resistance increases, λ ?
decreases
when transmembrane resistance increases, λ?
increases
describe shunting inhibition
- inhibitory synapse (is ) located usually near cell body
- excitation starts traveling down dendrite
- IS opens Cl- channels
- membrane resistance drops to -65 mv
- excitation shunted away
describe modulation
see notes
three types of EPSP summation
action potential (the norm)
spatial summation
temporal summation
what is spatial summation
multiple excitations form different pre-synaptic axons on the same axon
what is temporal summation
one pre-synaptic axon on one axon but AP follow one after the other
what is convergence
multiple NTs come to together to effect one system
what is divergence
one NT can activate multiple systems and elicit different responses
