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NAS > WEEK 4 > Flashcards

WEEK 4 Flashcards

1
Q

What causes Upper Motor Neurone signs

A

Damage to any aspect of the UMN

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2
Q

What causes Lower Motor Neurone signs

A

Damage to any aspect of the LMN or death or dysfunction to the muscle (disorders of MN’s soma/axon or NMJ)

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3
Q

Define innervation

A

normal state of nerve supply to a muscle/other target

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4
Q

Define denervation

A

depriving the muscle of its nerve supply

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5
Q

Define re-innervation

A

regrowth of the nerve to re-supply the muscle after denervation

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6
Q

What is often the result of re-innervation?

A

Original effector organ not always re-innervated, different effector organ innervated instead

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7
Q

Example of unsuccessful re-innervation

A

Crocodile tears syndrome due to re-innervation of tear glands from salivary glands-crying when smell/see food

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8
Q

What are the implications of disorders of a motor neurone’s cell body?

A

Loss or damage to the MN’s cell body (soma) leading to death of the MN

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9
Q

What is Polio Myelitis?

A

Communicable disease (polio virus) targeting LMN cell bodies in the ventral horn (known as infantile paralysis)

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10
Q

What is indicative of Polio Myelitis?

A

Atrophy (shrinking) of ventral (+dorsal) horns of spinal cord

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11
Q

What is the overall effect of Polio Myelitis?

A

Death of MNs leading to denervation hence paralysis of muscles they supply

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12
Q

What are the two variants of Motor Neurone Disease?

A

disease simultaneously killing UMN + LMN (progressive supranuclear palsy)
disease targets only LMN

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13
Q

What causes MND?

A

Spontaneous genetically programmed death (apoptosis) of body’s MN

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14
Q

Which motor neurones aren’t susceptible to MND?

A

MN supplying extraocular and anal sphincter muscles (neural root values S2-S4)

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15
Q

What are the implications of disorders of a motor neurone’s axon?

A

Loss or damage to MN’s axon doesn’t necessarily lead to MN death, however leads to denervation

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16
Q

What are two causes of MN axon disorders?

A

Complete transection of axons of MN (due to crushing/stabbing injuries)
Demyelination of axons of MN (Guillain-Barre Syndrome/Peripheral neuropathies)

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17
Q

How is Guillain-Barre syndrome acquired?

A

A complication following viral infection such as a common cold

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18
Q

What is caused by diabetic neuropathy?

A

Demyelination of both sensory and motor axons

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19
Q

What occurs with Guillem-Barre Syndrome when condition is cured/goes into remission?

A

Reversal of clinical signs

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20
Q

What are 3 examples of diseases to the NMJ?

A

Botulinum toxin (Botox)
Nerve gases
Myesthenia Gravis

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21
Q

What is Botulinum toxin (botox) and what effects does it have on the NMJ?

A

A toxin that depletes the Pre-S terminal of NMJ of it’s neurotransmitter causing paralysis of body muscles and potential death

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22
Q

What are nerve gases and what effects do they have on the NMJ?

A

A class of phosphorus-containing organic chemicals that block AChE from breaking down ACh in the NMJ

23
Q

Myesthenia Gravis

A

explained in previous week

24
Q

What are the implications of disorders of the muscle?

A

LMN sings of myogenic origin

25
Q

Give an example of a disorder of the muscle

A

Duchenne Muscular Dystrophy

26
Q

What is Duchenne Muscular Dystrophy?

A

Genetic condition resulting in progressive muscle weakness due to defects in muscle proteins, eventual death of individual

27
Q

Give four examples of LMN signs

A

Muscle atrophy (shrinking) due to denervation, Ptosis (drooping of eyelid(s)), Fasciculations (muscle twitching), negative Babinski (Plantar) reflex

28
Q

What is a local anaesthetic?

A

A medication that reversibly blocks nerve conduction when applied to a restricted area of the body to enable a procedure to be carried out without loss of consciousness

29
Q

What is the difference between LA and GA?

A

LA acts on restricted area, GA is body-wide/results in loss of consciousness

30
Q

Why are local anaesthetics used?

A

To prevent pain (nociception->senory receptor->AP-x->brain)

31
Q

Naming convention of local anaesthetics

A

-caine (suffix)

32
Q

What is the chemical structure of local anaesthetics?

A

aromatic ring-linkage-basic amine group

33
Q

What is the linkage for LAs?

A

Amide or ester

34
Q

What is the purpose of the linkage?

A

Site of metabolism (enzyme action)

35
Q

Which linkage has the faster rate of metabolism?

A

Ester

36
Q

What are the two key implications to consider for clinical use of LA?

A

Metabolism long enough to sustain procedural length and no allergic/toxic metabolites

37
Q

What does the aromatic ring of LA allow?

A

Lipid solubility (not if molecule is charged)

38
Q

What does the amine group of LA allow?

A

Ionisation (accepts proton)

39
Q

Are local anaesthetics weak acids/bases?

A

Weak bases

40
Q

What is the equation relating to LA ionisation?

A

LA + H20 ⇌ LA+ + OH-

41
Q

What determines LA ionisation state?

A

pH (increased acidity=more ionised (lipophobic), increased alkalinity=less ionised (lipophilic))

42
Q

Mechanism of LA action

A

unionised LA enters the cell due to lipophilicity, becomes ionised due to more acidic pH, ionised LA blocks V-gated Na+ ion channels, prevents Na+ influx, cells can’t depolarise

43
Q

What is use-dependent blocking?

A

Degree of block depends on whether channel is being used (LA+ block open channels therefore increased pain=increased block)

44
Q

What factor affects LA effectiveness and how is this altered?

A

Tissue pH which is made more acidic by inflammation/infection due to bacteria, causing more ionised LA-need proportion of LA to be unionised to travel through membrane

45
Q

Explain what is meant by different neurone sensitivity

A

Motor neurones are much less sensitive to LA than nociceptive axons due to having a much thicker axon, so are less affected

46
Q

What is the general principle of LA administration?

A

The more proximal the site of administration, the greater the area affected

47
Q

What is topical administration?

A

anaesthetising the skin or throat, not very effective as LA mol. can’t diffuse as quickly through densely packed skin cell structure

48
Q

What is infiltration administration?

A

injection into the skin, potentially a series of injections around area (eg. ‘ring block’)- eg. skin stitching

49
Q

What is nerve block anaesthesia?

A

injection given quite proximally- eg. whole/half jaw anaesthesia

50
Q

What is epidural anaesthesia?

A

injection into epidural space, into vertebrae not spinal cord therefore affecting nerve roots exiting spinal cord- eg. child birth

51
Q

What is spinal anaesthesia?

A

injection into CSF in subarachnoid space affecting spinal nerves in that space and spinal cord

52
Q

Side-effects of anaesthesia

A

Non-specific=related to other substance in LA solution-hypersensitivity (allergic) reactions
Specific=related to blocking of V-gated Na+ channels-high doses/injection into wrong area

53
Q

What are the other drugs administered with LA?

A

Preservatives

Vasoconstrictors-localise LA to decrease unwanted effects and increase duration of action

NAS (9 decks)

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