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

PoH: How Nerves Work Flashcards

(72 cards)

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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
Do graded potentials decay as they travel?
Yes
26
Do action potentials decay as they travel?
No - they're self propogating
27
Where are action potentials evoked?
At the initial segment
28
Do graded potentials have a refractory period?
No
29
Do action potentials have a refractory period?
Yes
30
When is equilibrium reached for leaky K+ channels?
When the gradient is equal and opposite to the concentration gradient
31
Define electrogenic and explain how it relates to RMP
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
What does the Nernst Equation tell us?
The equilibrium potential is the membrane potential at which the electrical gradient is equal and opposite to the concentration gradient
33
What does the Goldman-Hodgkin-Katz Equation let us predict?
The equilibrium potential generated by several ions
34
Do the following refer to graded or action potentials: Decremental, summate, depolarising/hyperpolarising
Graded
35
What is Excitatory Post Synaptic Potential (EPSP)?
It makes it more likely to generate an action potential
36
What receptors do fast ESPS use and what's their mechanism?
Ionotrophic receptors - they depolarise a neurone's membrane, making it more likely to fire an action potential
37
What receptors do slow EPSPs use and what's their mechanism?
Metabotrophic receptors - they close leaky K+ channels, so only the sodium-potassium pump leads to change
38
What are Inhibitory Post-Synaptic Potentials?
They make it less likely to generate an action potential
39
What receptors do fast IPSPs use and what's their mechanism?
Ionotrophic receptors - hyperpolarise neurone's membrane, making it less likely to fire an action potential
40
What receptors do slow IPSPs use and what's their mechanism?
Metabotrophic receptors - open leaky K+ channels so only sodium-potassium pump leads to change
41
Do ionotrophic receptors provide fast or slow EPSP/IPSPs?
Fast
42
Do metabotrophic receptors lead to fast or slow EPSP/IPSP?
Slow
43
Explain synaptic integration
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
What 3 types of synapses can be found on a neurone's dendrites?
Axo-dendritic synapse Axo-somatic synapse Axo-axonic synapse
45
Name 2 types of summation
Temporal summation and spatial summation
46
Name the 5 types of nerve fibres
Aa, aB, Ay, Ad, C
47
What 2 features of neurones can speed up an action potential?
Large axons and myelination
48
What type of nerve fibre is useful for proprioception and motor neurones?
Aa/Largest myelinated - it's got the fastest velocity
49
What type of nerve fibre is useful for pressure and touch?
AB/Large myelinated
50
What type of nerve fibre is useful for warmth and slow pain?
C/Unmyelinated - it's got the slowest velocity
51
Name two types of demyelinating disease
MS (in CNS) and Guillain-Barre syndrome (in PNS)
52
What effect do demyelinating diseases have on neurones?
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
Define end plate potential
The voltage which causes depolarisation of muscle fibres, caused by neurotransmitters binding to the postsynaptic membrane in the neuromuscular junction
54
Is neuromuscular transmission graded?
No
55
What are post junctional folds at the NMJ?
Increase the number of voltage-gated Na+ channels
56
What diffuses across the synaptic cleft?
ACh
57
Name the type of channel and ion that opens at the presynaptic terminal at the NMJ
Voltage-gated Ca2+ channel
58
What receptors does ACh bind to?
Nicotinic
59
What cleans up ACh at the NMJ?
Acetylcholinesterase
60
ACl is the only one acting at the NMJ. What receptors can it bind to?
Cholinergic, nicotinic and ionotrophic
61
Name 5 amine neurotransmitters
Adrenaline Noradrenaline Dopamine Serotonin (5HT) Histamine
62
Name 3 amino acid neurotransmitters and whether they're excitatory or inhibitory
Glutamate - excitatory GABA - inhibitory Glycerine - inhibitory
63
Name 3 peptide neurotransmitters
Endorphins Cholecystokinin Substance P
64
Name 2 purine neurotransmitters
ATP Adenosine
65
Name a gas acting as a neurotransmitter
Nitric oxide
66
What 5 types of neutotransmitters are there in the CNS?
Amines Amino acids Peptides Purines Gases
67
What type of receptor is a fast EPSP/IPSP?
Ionotrophic
68
What type of receptor is a slow EPSP/IPSP?
Metabotrophic
69
What 2 ways can a synapse connect to other synapses?
Divergence and convergence
70
Define feedback inhibition and explain its purpose
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
What does a polysynaptic reflex have that a monosynaptic reflex doesn't?
Interneurone(s)
72
Define synaptic plasticity
Changes in strength of synapses. It can be activity dependent

Medicine - Year 1 - Term 1 (10 decks)

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