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Medicine - Year 1 - Term 1 > PoH: How Nerves Work > Flashcards

PoH: How Nerves Work Flashcards

1
Q

Which part of a neurone receives information?

A

Dendrite

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2
Q

Which part of a neurone triggers the action potential?

A

The initial segment/Axon hillock

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3
Q

Which part of a neurone contains the nucleus

A

Cell body/Soma

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4
Q

Which part of a neurone sends action potentials?

A

Axon

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5
Q

Which part of a neurone releases neurotransmitter?

A

The axon’s presynaptic terminals

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6
Q

Where is a motor/efferent neurone’s cell body?

A

Ventral horn of spinal cord

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7
Q

What type of neurone can have a bipolar of pseudounipolar shape?

A

Afferent/sensory

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8
Q

What type of neurone can have a multipolar or anaxonic shape?

A

Interneurone

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9
Q

What type of neurone can have a multipolar (but not anaxoniac) shape?

A

Efferent/motor neurone

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10
Q

What do sensory/afferent neurones do?

A

Detect a stimulus and send a signal to the CNS

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11
Q

What 3 things could a motor/efferent neurones target?

A

A muscle, gland or neurone

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12
Q

What is an action potential?

A

Transmitting a signal over a long distance

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13
Q

What is a graded potential

A

Deciding whether an action potential should be fired

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14
Q

Define resting membrane potential

A

It keeps cell ready to respond. Most cells have a RMP where the inside is negative relative to the outside – determined by the size of the initial concentration gradient

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15
Q

What causes RMP?

A

Leaky K+ channels in most neurones

Leaky K+, Na+ and Cl- channels in most other cells

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16
Q

Provide a value for RMP in most neurones, and a value for most other cells

A

-70 mV in neurones (due to leaky K+ channels)
-90 mV in other cells (due to leaky K+, Na+ and Cl- channels)

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17
Q

Can graded potentials summate?

A

Yes

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18
Q

Can action potentials summate?

A

No

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19
Q

Do graded potentials have a threshold?

A

No

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20
Q

Do action potentials have a threshold?

A

Yes

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21
Q

What channels mediate graded potentials?

A

Ligand-gated channels

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22
Q

What channels mediate action potentials?

A

Voltage-gated channels

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23
Q

Do graded potentials have various or fixed amplitude?

A

Various

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24
Q

Do action potentials have various or fixed amplitude?

A

Fixed

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25
Q

Do graded potentials decay as they travel?

A

Yes

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26
Q

Do action potentials decay as they travel?

A

No - they’re self propogating

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27
Q

Where are action potentials evoked?

A

At the initial segment

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28
Q

Do graded potentials have a refractory period?

A

No

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29
Q

Do action potentials have a refractory period?

A

Yes

30
Q

When is equilibrium reached for leaky K+ channels?

A

When the gradient is equal and opposite to the concentration gradient

31
Q

Define electrogenic and explain how it relates to RMP

A

It makes the inside of the cell slightly negative

It relates to RMP due to the sodium-potassium pump where 3 Na+ is exchanged for 2 K+. The inequal amount leads to the inside of the cell being negative

32
Q

What does the Nernst Equation tell us?

A

The equilibrium potential is the membrane potential at which the electrical gradient is equal and opposite to the concentration gradient

33
Q

What does the Goldman-Hodgkin-Katz Equation let us predict?

A

The equilibrium potential generated by several ions

34
Q

Do the following refer to graded or action potentials: Decremental, summate, depolarising/hyperpolarising

A

Graded

35
Q

What is Excitatory Post Synaptic Potential (EPSP)?

A

It makes it more likely to generate an action potential

36
Q

What receptors do fast ESPS use and what’s their mechanism?

A

Ionotrophic receptors - they depolarise a neurone’s membrane, making it more likely to fire an action potential

37
Q

What receptors do slow EPSPs use and what’s their mechanism?

A

Metabotrophic receptors - they close leaky K+ channels, so only the sodium-potassium pump leads to change

38
Q

What are Inhibitory Post-Synaptic Potentials?

A

They make it less likely to generate an action potential

39
Q

What receptors do fast IPSPs use and what’s their mechanism?

A

Ionotrophic receptors - hyperpolarise neurone’s membrane, making it less likely to fire an action potential

40
Q

What receptors do slow IPSPs use and what’s their mechanism?

A

Metabotrophic receptors - open leaky K+ channels so only sodium-potassium pump leads to change

41
Q

Do ionotrophic receptors provide fast or slow EPSP/IPSPs?

A

Fast

42
Q

Do metabotrophic receptors lead to fast or slow EPSP/IPSP?

A

Slow

43
Q

Explain synaptic integration

A

Each neuron has 100s of excitatory and inhibitory synapses, evoking fast/slow EPSPs/IPSPs, each one is only a few mV high. Adding them together pushes the cell to threshold and fires an action potential or keeps cell away from threshold and tells it to shut up. The concept of synaptic integration is the summation of the synaptic inputs to decide if the initial segment will reach threshold.

44
Q

What 3 types of synapses can be found on a neurone’s dendrites?

A

Axo-dendritic synapse
Axo-somatic synapse
Axo-axonic synapse

45
Q

Name 2 types of summation

A

Temporal summation and spatial summation

46
Q

Name the 5 types of nerve fibres

A

Aa, aB, Ay, Ad, C

47
Q

What 2 features of neurones can speed up an action potential?

A

Large axons and myelination

48
Q

What type of nerve fibre is useful for proprioception and motor neurones?

A

Aa/Largest myelinated - it’s got the fastest velocity

49
Q

What type of nerve fibre is useful for pressure and touch?

A

AB/Large myelinated

50
Q

What type of nerve fibre is useful for warmth and slow pain?

A

C/Unmyelinated - it’s got the slowest velocity

51
Q

Name two types of demyelinating disease

A

MS (in CNS) and Guillain-Barre syndrome (in PNS)

52
Q

What effect do demyelinating diseases have on neurones?

A

They attack the myelin sheath, leading to:

Decreased membrane resistance (more current leaks out)

Increased membrane capacitance (more current wasted charging up the membrane)

53
Q

Define end plate potential

A

The voltage which causes depolarisation of muscle fibres, caused by neurotransmitters binding to the postsynaptic membrane in the neuromuscular junction

54
Q

Is neuromuscular transmission graded?

A

No

55
Q

What are post junctional folds at the NMJ?

A

Increase the number of voltage-gated Na+ channels

56
Q

What diffuses across the synaptic cleft?

A

ACh

57
Q

Name the type of channel and ion that opens at the presynaptic terminal at the NMJ

A

Voltage-gated Ca2+ channel

58
Q

What receptors does ACh bind to?

A

Nicotinic

59
Q

What cleans up ACh at the NMJ?

A

Acetylcholinesterase

60
Q

ACl is the only one acting at the NMJ. What receptors can it bind to?

A

Cholinergic, nicotinic and ionotrophic

61
Q

Name 5 amine neurotransmitters

A

Adrenaline
Noradrenaline
Dopamine
Serotonin (5HT)
Histamine

62
Q

Name 3 amino acid neurotransmitters and whether they’re excitatory or inhibitory

A

Glutamate - excitatory
GABA - inhibitory
Glycerine - inhibitory

63
Q

Name 3 peptide neurotransmitters

A

Endorphins
Cholecystokinin
Substance P

64
Q

Name 2 purine neurotransmitters

A

ATP
Adenosine

65
Q

Name a gas acting as a neurotransmitter

A

Nitric oxide

66
Q

What 5 types of neutotransmitters are there in the CNS?

A

Amines
Amino acids
Peptides
Purines
Gases

67
Q

What type of receptor is a fast EPSP/IPSP?

A

Ionotrophic

68
Q

What type of receptor is a slow EPSP/IPSP?

A

Metabotrophic

69
Q

What 2 ways can a synapse connect to other synapses?

A

Divergence and convergence

70
Q

Define feedback inhibition and explain its purpose

A

When an action potential is fired, a collateral branch activates an inhibitory interneuron. It releases inhibitory neurotransmitter, hyperpolarising the original neurone

It prevents repeat firing

71
Q

What does a polysynaptic reflex have that a monosynaptic reflex doesn’t?

A

Interneurone(s)

72
Q

Define synaptic plasticity

A

Changes in strength of synapses. It can be activity dependent

Medicine - Year 1 - Term 1 (10 decks)

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