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Brain And Behaviour > Lecture 3- Neurotransmission > Flashcards

Lecture 3- Neurotransmission Flashcards

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1
Q

NT 1

A

Within a neuron

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2
Q

NT 2

A

Between neurons

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3
Q

Dendrites

A

Recipient of information from other neurons, large receptive field

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4
Q

Soma

A

Contains the tools that control processing in the cell and integrates info

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5
Q

Axon

A
  • Uses action potential to pass info from the soma to the terminal boutons
  • Can contact multiple neurons
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6
Q

Terminal boutons

A
  • Found at the end of the axon

- Communication point with other neuron

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7
Q

Neural membrane

A
  • Boundary of soma, dendrites, axon and terminal boutons
  • Lipid bilayer
  • Separates extracellular and intracellular
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8
Q

1930s Hodgkin and Huxley

A
  • Used squids giant axon in sea water
  • Measured electrical voltage
  • Placed microelectrodes inside and outside membrane
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9
Q

Membrane potential

A

Electrical charge across the membrane

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10
Q

At rest difference between inside and outside of neurons is

A

Approximately 65-70 mV (millivolts)

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11
Q

At rest inside of neurons is more

A

Negatively charged than the outside

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12
Q

What causes there to be a membrane potential

A

Force of diffusion

Force of electrostatic pressure (particles moving to opposite charge Na+ -> negatively charged)

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13
Q

Equilibrium potential

A

Outward movement = inward movement

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14
Q

Resting membrane potential results from

A

The separation of charge across the membrane

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15
Q

What are Organic anions

A
  • Big and heavy

- Influence the neuron charge

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16
Q

At rest which channels are more open

A

K+ channels open more than Na+

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17
Q

At rest high concentration of

A
  • Na+ outside neuron

- High concentration of K+ inside neuron

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18
Q

What’s the Nernst Equation

A

The equilibrium potential can be calculated for any ion using this

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19
Q

If you have a bigger ion concentration outside than inside what is the equilibrium potential

A

Positive equilibrium potential

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20
Q

Sodium-Potassium pump maintains

A

Ionic concentration gradients across the membrane and therefore membrane potential

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21
Q

If potassium was the only ion moving the potential would stabilise at

A

-90 mV

However, positively charged sodium ions leak into the neuron, raising it to -70

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22
Q

Where is action potential generated

A

Axon hillock

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23
Q

Action potentials are generated by

A
  • The summation of converging inputs from the dendrites or

- Electrical stimulation (experimentally)

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24
Q

Hyperpolerisation is a membrane potential that’s

A

More negative than resting membrane potential (RMP)

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25
Q

Ways of achieving hyperpolarisation

A
  • Injection of small negative current
  • Positive ions move out
  • Negative ions move in
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26
Q

Depolarisation is membrane potential that’s

A

More positive than Resting membrane potential (RMP)

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27
Q

Ways of achieving depolarisation

A
  • Injection of small positive current

- Positive ions move in

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28
Q

What is conductance

A

Small depolarisation to a neuron

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29
Q

Conductance affects what part of the axon the most

A

Positivity is bigger towards the injection site than away

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30
Q

What is decremental conductance

A

As you go along the axon conductance is decaying

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31
Q

What is an action potential in relation to depolarisation

A

Increase the size of the stimulation and therefore the degree of depolarisation

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32
Q

What is the threshold of an action potential

A

-50mV

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33
Q

What does the term voltage gated channels mean

A

Opened when the membrane becomes depolarised

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34
Q

Voltage clamp experiments use injecting a current into the axon to create

A

A steady membrane potential

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35
Q

Voltage clamp experiments record

A

The membrane current

36
Q

What does Sodium look like with Voltage clamp experiments

A

Fast movement of ions into the neuron through the Na+ channels, looks like a spike then flatline

37
Q

What does a Potassium current look like with Voltage clamp experiments

A

Movement of ions out of the neuron through the K+ channels, Curve up

38
Q

What is conductance rate

A

The rate of ion travel through channel

39
Q

What is a refractory period

A

Voltage gated channels are no longer working

40
Q

Which gate is in use in rest of Voltage gated channels

A

Activation gate

41
Q

Which gate is in use in open Voltage gated channels

A

Neither, gates open

42
Q

Which gate is in use when refractory Voltage gated channels

A

Inactivation gate

43
Q

What is enough depolarisation to open K+ channels

A

Close to -10,-20

44
Q

At resting membrane potential most channels are

A

Closed

45
Q

Small depolarisation opens

A

A few Na+ channels leading to further depolarisation

46
Q

If stimulation (action potential) is large enough what channels will open

A

Na+ channels, more Na+ moves into the neuron

47
Q

As the neuron continues to depolarise, what channels start to open

A

Some K+ channels, allowing K+ to leave the neuron

48
Q

After the peak of the action potential what begins to happen to channels

A
  • Na+ channels become deactivated

- Remaining K+ channels open and K+ continues to leave the neuron

49
Q

K+ leaving the neuron through diffusion is

A

Repolarisation

50
Q

What is hyperpolarisation

A
  • K+ channels begin to close
  • Na+ channels return to closed state (resting)
  • Membrane potential drops below RMP
51
Q

What happens after hyperpolarisation

A

K+ channels close and external K+ is diffused away

Membrane returns to RMP due to ATP pumps

52
Q

Action potential is how big along the axon

A

The same size along the axon

53
Q

What is bioelectric medicine

A

Application of understanding about neuronal circuits and electrical impulses

54
Q

What are oligodendrocytes

A
  • Asymmetrical

- Forms myelin around axons in brain and spinal cord

55
Q

What are Schwann cells

A
  • Asymmetrical

- Wraps around peripheral nerves to form myelin

56
Q

At myelinated axons where can axons only occur

A

Nodes of ranvier as that’s the only time Na+ and K+ can release

57
Q

Advantages of myelinated axons

A

-Less action potentials needed

58
Q

What is multiple sclerosis

A
  • Damage to myelin sheath

- Loss of sensitivity, muscle weakness, difficulty with coordination and balance

59
Q

What’s tetrodotoxin

A
  • From puffer fish
  • Blocks voltage gated Na+ channels
  • No cure
  • Paralysis, conscious while you die
60
Q

What is alpha-dendrotoxin

A
  • From green mamba
  • Blocks voltage gated K+ channels
  • Leads to convulsions
61
Q

What effects do cocaine, benzocaine and lidocaine have

A
  • Voltage gated Na+ channel blockers

- Used as anaesthetics

62
Q

What are the types of synapses

A
  • Electrical

- Chemical

63
Q

Electrical synapse

A
  • Very rare in adult mammalian neuron’s
  • Junction between neurons is very small
  • Ions can move freely resulting in fast electrical transmission
64
Q

Chemical synapses

A
  • Common in adult mammalian neurons

- Neurotransmitters are released from presynaptic to post

65
Q

What are the three types of synapses

A
  • Axodendritic, axon to dendrite (most)
  • Axosomatic, axon to soma
  • Axoaxonic, axon to axon
66
Q

Why does it matter where the location of the synapse is

A
  • The closer the synapse is to the soma the greater it’s influence on production of an action potential
  • Due to decremental decay
67
Q

When action potential gets to the synapse depolarisation

A

Opens voltage gated calcium

68
Q

Criteria for neurotransmitters

A
  • Chemical synthesised presynaptically
  • Electrical stimulation leads to the release of the chemical
  • Chemical produces physiological effect
  • Terminal activity
69
Q

What’s Dales Law

A

If a Neurotransmitters released by one of a neurons synaptic endings, the same chemical is released at all synaptic endings of the neuron

70
Q

Calcium influx allows for

A

Vesicles to fuse with the synaptic membrane

71
Q

What do metabotropic receptors do

A
  • Activate an internal second messenger system that goes on to affect the functioning of postsynaptic cells
  • Amplified response
72
Q

What do ionotropic receptors do

A

Open an ionic channel (typically)

73
Q

What is an excitatory transmission

A
  • Movement of positive ions into the neuron
  • Depolarisation
  • Excitatory post synaptic potential
74
Q

Inhibitory fast transmission

A
  • Movement of negative ions into the neuron
  • Hyperpolarisation
  • Inhibitory post synaptic potential
75
Q

What is the metabotropic receptor

A
  • G protein coupled receptors

- GPCR

76
Q

What are the stages of GPCR

A
  • Neurotransmitter binds to receptor causing GDP to be exchanged for GTP
  • G protein splits and activates other enzymes
  • Breakdown of GTP turns off G protein activity
  • Chemical reactions lead to amplified signal
77
Q

What are the ways of neurotransmitter deactivation

A
  • Deactivatating enzyme

- Reuptake

78
Q

What does Glutamate do

A
  • Causes major fast excitatory neurotransmitter in the CNS
  • Very widespread through the CNS
  • Activates different types of receptors
79
Q

What is normal neuronal transmission of glutamate used for

A

Involved in learning and memory processing

80
Q

What types of neural integration are there

A
  • Spatial, three inputs coming in at once from different axons
  • Temporal, multiple action potentials coming from the same axon
81
Q

What does GABA do

A
  • Major inhibitory neurotransmitter

- Activates an iontropic receptor which leads to hyper-polarisation

82
Q

GABA receptor is enhanced by

A
  • Ethanol
  • Benzodiazepines
  • Barbiturates
  • Neurosteroids
83
Q

EPSP can be decreased or abolished by

A

IPSPs from inhibitory neurons that are active at the same time

84
Q

Autoreceptors

A
  • Located on the presynaptic cleft
  • Respond to neurotransmitters in the synaptic cleft
  • Regulate internal process controlling synthesis and release of neurotransmitter
  • Generally g-protein coupled
  • Don’t cause depolarisation
  • Negative feedback receptors
85
Q

Autoreceptors are not the same as

A

Reuptake sites

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