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PSC3008 > lecture 4 - claudia racca > Flashcards

lecture 4 - claudia racca Flashcards

1
Q

what are the two types of receptors

A

ionotropic and metabotropic

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2
Q

what are receptors distinguished by

A

the NT that they bind to

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3
Q

what are the types of receptors that bind to ACh

A

muscarinic and nicotinic

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4
Q

what are the types of receptors that bind to glutamate

A

NMDA
non-NMDA (AMPA and kainate)

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5
Q

what are the types of the receptors that bind to GABA

A

GABAa
GABAb
etc

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6
Q

what is the main excitatory NT

A

glutamate

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7
Q

are glutamate receptors (AMPA, NMDA and kainate) ionotropic or metabotropic

A

ionotropic receptors

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8
Q

How does the NMDA receptor function

A

At resting membrane potential (~65mV) the receptor is blocked by Mg2+ molecule in the pore.
when the membrane depolarises the Mg2+ moves out of the pore.
The NMDA receptor also requires glycine as well as glutamate to open.
Then calcium and sodium can move in and potassium out.

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9
Q

examples of ionotropic receptors

A
  • ACh nicotinic
  • Glutamate (AMPA, NMDA and kainate)
  • GABAa
  • Glycine receptor
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10
Q

examples of metabotropic receptors

A
  • ACh muscarinic
  • Glutamate metabotropic
  • GABAb
  • 5HT receptor
  • Dopamine receptor
  • NE receptor
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11
Q

what is an autoreceptor

A

receptors on the presynaptic membrane

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12
Q

what do autoreceptors do

A

regulate neurotransmitter synthesis and release

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13
Q

excitatory receptors cause

A

depolarisation of the post synaptic membrane by sodium moving across the membrane

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14
Q

inhibitory receptors cause

A

hyperpolarisation of the post synaptic membrane by chloride ions moving across the membrane

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15
Q

how do metabotropic receptors work

A

they are G protein coupled

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16
Q

how many membrane spanning domains do metabotropic receptors have

A

7

17
Q

G protein can also be inhibitory or excitatory

A

Gs - stimulates effector protein
Gi - inhibits effector protein

18
Q

two metabotropic effector systems

A

shortcut (GABAb, mACh)
2nd messenger cascade (NE)

19
Q

G protein shortcut pathway

A

ACh binds to the muscarinic receptor and activates the G protein and the alpha subunit which is bound to GTP phosphorylates the potassium channel which will then open.

20
Q

G protein 2nd messenger cascade pathway

A

activation of the G protein causes phosphorylation of an enzyme and this causes a signalling cascade
takes longer but creates a stronger response (more channels open)

21
Q

a single neuron receives thousand of synapses and the inputs may be…

A

excitatory and inhibitory

22
Q

these inputs interact to produce a…

A

synaptic potential
if above threshold the cell will fire an action potential

23
Q

what are the different types of synapses

A

axodendritic
axosomatic
axoaxonic

24
Q

EPSP spatial summation

A

multiple excitatory synapses coming in to the same dendrite at the same time
causes a large increase in membrane potential

25
Q

EPSP temporal summation

A

one synapse on a dendrite but there are multiple APs coming in from the same axon within 1-15ms of each other
the individual EPSEs generated at the same synapse add together.

26
Q

whether or not an EPSE contributes to the generation of an AP depends on

A
  • number of coactive synapses
  • distance of the synapse from the spike initiation zone in the axon
  • properties of dendritic membrane
  • nature of the synapses (excitatory vs inhibitory)
27
Q

current is injected into the dendrite and the depolarisation is recorded. as this current spreads down the dendrite, much of it dissipates across the membrane. therefore the depolarisation (EPSP) measured at a distance from the site of current injection is…

A

smaller than that measured at the site of injection

28
Q

voltage gated channels are present on dendrites and can…

A

amplify small EPSPs

29
Q

inhibitory synapse causes the depolarising current from the excitatory synapse to leak out before it reaches the soma. this is called…

A

shunting

30
Q

the effect of NE binding to NE beta receptors

A
  • NE binding to beta receptors activated G protein
  • G protein activates the enzyme adenylyl cyclase
  • adenylyl cyclase converts ATP –> cAMP
  • cAMP activated a protein kinase
  • kinase phosphorylates a potassium channel in the dendrite
  • phosphorylation causes potassium channel to close
  • closure of potassium channels insulates the dendrite, excitable signals spread to soma more easily
31
Q
A

PSC3008 (28 decks)

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