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Flashcards in synaptic transmission Deck (59)
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1
Q

Opening Na channels

A

depolarises the cell (excitatory)

2
Q

Opening K+ channels

A

hyperpolarises the cell (inhibitory)

3
Q

Opening Cl- channel

A

hyperpolarises the cell (inhibitory)

4
Q

Opening Ca+ channels

A

depolarises the cell (excitatory)

5
Q

EPSPs

A

excitatory post synaptic potentials

6
Q
  • Excitatory PSPs
A

○ Depolarise the membrane (more +ve)
○ Open some Na+ or Ca+ channels
○ Increases probability of AP

7
Q

IPSPs

A

Inhibitory post synaptic potentials

8
Q

Inhibitory post synaptic potentials

A

○ Hyperpolarise membrane (more negative)
○ Open some Cl- or K+ channels
○ Decreases probability of AP

9
Q

post synaptic potentials

A
  • PSPs are not all or nothing
    • They are graded
    • ESPSs and IPSPs are summed (spatially and temporally) to decided whether the neurone generates an AP
10
Q

Threshold for AP generation

A
  • If the axon trigger zone exceeds -55mV, all voltage gated Na+ channels open and AP is generated
11
Q

all voltage gated Na+ channels open and AP is generated when

A

If the axon trigger zone exceeds -55mV

12
Q

The sum of all IPSPs and EPSPs cause

A

either depolarisation of hyperpolarisation

13
Q

IPSPs cause

A

hyperpolarisation

14
Q

EPSPs cause

A

depolarisation

15
Q

2 ways neurones generate PSPs

A

direct electrical transmission

by use of a chemical mediator

16
Q

○ Direct electrical transmission

A

§ Rare

§ Cardiac muscle, some types of smooth muscle and some neurons

17
Q

By use of a chemical mediator

A

§ Common

§ Neuron and muscle, neuron and neuron, sensory receptor cells and neurons

18
Q

direct electrical synapses

A
  • APs (ions) travel through gap junctions between presynaptic and postsynaptic neurons
    • Synapse has gap junctions - hole in the plasma membrane of both cells where ions can flow through
      ○ Allows Na to flow into the post synaptic neurone
19
Q

Chemical synapses

A
  • Neurotransmitter molecules cross the synapse and signal the post synaptic neuron by binding receptors and inducing change
20
Q

○ Glutamate decarboxylase

A

Takes off a carboxyl group and it changes from glutamate to GABA

21
Q

choline acetyltransferase

A

puts Acetyl CoA and choline together to make acetyl choline

22
Q

adrenaline made from

A

modified tyrosine

23
Q

how are neurotransmitters stored

A

in vesicles

24
Q

where are nuerotransmitter containing vesicles stored

A

docked at the cell membrane

25
Q

how are nuerotransmitter containing vesicles released

A

exocytosis

26
Q

how is exocytosis of neurotransmitter containing vesicle triggered

A

action potential

27
Q

v-snare on neurotransmitter vesicle

A

synaptobrevin

28
Q

t-snare on cell membrane

A

SNAP

29
Q

why do synaptobrevin and SNAP only partially assemble

A

blocked by complexin

stops them from binding

30
Q

how does SNAP and synaptobrevin fuse

A
  • Synaptotagmin is activated by Ca+ and moves complexin out the way
31
Q

synaptotagmin is activated by

A

Calcium

32
Q

how does calcium get to the presynaptic nerve

A

presynaptic terminus contains voltage gated calcium channels instead of voltage gated sodium channels
AP depolarises and Ca channels open
Ca binds synaptotagmin

33
Q

2 classes of receptors

A

ionotropic and metabotropic

34
Q

ionotropic receptors

A

open/close an ion channel

○ Ligand gated ion channels

35
Q

metabotropic receptors

A

○ Active an enzyme
○ Ligand binding outside cell activates enzyme inside the cell
○ Receptor tyrosine kinases, G-protein coupled receptors

36
Q

acetyl choline nuerotransmitter can have multiple effects

A
  • Excitatory: Nicotinic - opens Na+ channels

- Inhibitory: Muscarinic - opens K+ channels

37
Q

two main neurotransmitters of the CNS

A

glutamate and GABA

38
Q

two main neurotransmitters of the PNS

A

acetylcholine and noradrenaline

39
Q

glutamate is

A

dominant excitatory neurotransmitter in the CNS

40
Q

glutamate acts via

A

iGluRs and mGluRs

inotropic and metabotropic glutamate receptors

41
Q

iGluRs activated by glutamate

A

AMPA - Na Channel
NMDA Na and Ca channel
both EPSPs

42
Q

GABA is

A

The dominant inhibitory CNS neurotransmitter

43
Q

GABA binds

A

GABA alpha receptors (ionotorpic)

GABA beta receptors (metabotropic)

44
Q

GABA alpha receptors

A

ionotropic
Cl- channels causing influx of Cl- causing hyper polarisation
IPSP

45
Q

acetyl choline

A

○ Excitatory or inhibitory

PNS nuerotransmitter

46
Q

when is acetyl choline excitatory

A

§ Nicotinic receptors
□ Ionotropic - ligand gated Na+ channel
□ Always excitatory

47
Q

when is acetyl choline inhibitory

A

§ Muscarinic - often inhibitory, can be excitatory

□ Metabotropic - activates enzymes

48
Q

noradrenaline

A

PNS nuerotransmitter

excitatory or inhibitory

49
Q

2 types of receptors triggered by noradrenaline

A

alpha and beta adrenergic

moth metabotropic, activate enzymes and can be excitatory or inhibitory

50
Q

heart rate is controlled by

A

acetyl choline and noradrenaline

51
Q

noradrenaline and acetyl choline are

A
  • Antogonists - one is excitatory and one is inhibitory
52
Q

speeding up heart rate

A
  • Noradrenaline -excitatory

○ Bind to beta adrengeric which opens ca;cium channel to excite the cell - heart rate speeds up

53
Q

slowing heart rate

A
  • Acytyl choline binds to muscarinic receptor to open potassium chanel to hyperpolarise the cell and inhibit it to slow the heart rate
54
Q

2 ways of stopping neurotransmitters

A

neurotransmitter reuptake

nuerotransmitter degredation

55
Q
  • Neurotransmitter reuptake
A

○ Uptake by presynaptic neuron or local glial cells

○ Most NT: serotonin, glutamate, dopamine, noradrenaline, GABA

56
Q
  • Neurotransmitter degradation
A

○ Enzymes in the synapse chew up neurotransmitter molecules

○ Mostly done with acetyl choline

57
Q

making acetyl choline

A

choline acetyltransferase

58
Q

degrading acetyl choline

A

acetylcholinesterase

59
Q

how is the process of clearing nuerotransmitter sped up

A

glial cells uptake nuerotransmitter