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Neuro junior > Neuromuscular junction and dz > Flashcards

Neuromuscular junction and dz Flashcards

1
Q

Anatomy of Neuromuscular junction

A
  1. Nerve
    - Root (within spinal canal)
    - Peripheral nerve
  2. Junction
    - presynaptic endplate
    - synaptic cleft
    - post-synaptic membrane
  3. Muscle
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2
Q

Lower motor neuron reflex arc

A
  1. Afferent nerve to
  2. Synapse in dorsal root ganglion to
  3. Dorsal horn to
  4. Synapse in ventral horn to
  5. Two pathways from there
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3
Q

Resting membrane potential for a large nerve fiber

A

~-90 millivolts

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4
Q

Depolarization

A
  1. inc Na+ permeability, influx of positive

2. Potential may approach zero or….?

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5
Q

Repolarization

A
  1. Na+ channels begin to close
  2. K+ channels open more
  3. Re-establishment of RMP
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6
Q

Defecit in Ca

A

Causes Na+ channels to become activated with little increases in membrane potential -> tetany (exciteability)

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7
Q

High extracellular Ca+

A

Decreases membrane permeability to Na+ and reduces exciteability

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8
Q

Local anesthetics (3)

A
  1. Na+ channel blockers
  2. Act on sodium channel activation gates
  3. Reduce excitability
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9
Q

When Action Potential strength to excitability threshold is < 1

A

Nerve impulses are not conducted

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10
Q

Anatomy of the neuron (5)

A
  1. Dendrites (receptor endings)
  2. Perikaryon (cell body)
  3. Axon
  4. Collateral branches
  5. Axon terminals
  6. Synaptic bulb
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11
Q

Myelin sheath

A

On CNS nerves I think

-Oligodendroglial cell processes

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12
Q

Schwann cells on

A

PNS nerves I think

-Rolled up Schwann cell membrane

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13
Q

Things with no myelination (4)

A
  1. Initial segment
  2. Axon hillock
  3. Nodes of Ranvier
  4. Axon terminals
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14
Q

Larger nerves have faster

A

conduction

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15
Q

Saltatory conduction (2)

A
  1. Increases velocity

2. Conserves energy with only nodes depolarizing

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16
Q

Presynaptic terminal elements (2)

A
  1. Transmitter vesicles
    - excitatory or inhibitory
  2. Mitochondria
    - Provide ATP for transmitter synthesis
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17
Q

Depolarization of presynaptic membrane (3)

A
  1. Depolarized by Action potential
  2. Opens voltage-gated Ca channels
  3. Amount of Ca inflow is directly related to transmitter released
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18
Q

Postsynaptic receptor proteins (2)

A
  1. Binding component protruding into cleft

2. Ionophore component

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19
Q

Ionophore component (2)

A
  1. Ion Channel-rapid

2. Second messenger activator-slow, I think

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20
Q

Ion channel (2)

A
  1. Cation channels: allow entrance of Ca ->excitatory

2. Anion channels: allow entrance of Cl- -> inhibitory

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21
Q

‘second messenger’ activator (2)

A
  1. For prolonged postsynaptic neuronal changes

2. G-proteins

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22
Q

Neurotransmitters (2)

A
  1. Small molecules (rapidly action)

2. Neuropeptides (slowly acting or growth factors)

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23
Q

Small, rapidly acting neurotransmitters (4)

A
  1. Class I (ACh)
  2. Class II: Amines
    - norepi, epi, dopamine, serotonin, histamine
  3. Class III: Amino Acids
    - GABA, Gly, Glutamate, Aspartate
  4. Class IV (NO)
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24
Q

Neuropeptides, slow neurotransmitters (4)

A
  1. Hypothalamic-RH
    - TRH, LHRH, Somatostatin
  2. Pituitary peptides
    - ACTH, GH, ADH
  3. Peptides GI, Brain
    - Enkephalins, gastrin, VIP, insulin, glucagon
  4. Other
    - Bradykinin, Angiotensin II
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25
Q

Things affecting synaptic transmission (4)

A
  1. Fatigue-dec in d/c of postsynaptic neuron
  2. pH-alkalosis inc excitability/acidosis depresses excit
  3. Hypoxia-cessation 3-7 seconds-> unconscious
  4. Drugs
    - Caffeine (reduces threshold)
    - Strychnine-inhibits glycine in spinal cord
    - Anesthetics-inc threshold for excitation-> decreases transmission
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26
Q

Drugs stimulating muscle fiber by ACh-like action (3)

A
  1. Methacholine
  2. Carbachol
  3. Nicotine
    * These aren’t broken down by cholinesterase (last longer)
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27
Q

Drugs that stim NMJ by inactivating ACh (3)

A
  1. Neostigmine
  2. Physostigmine
  3. Diisopropyl fluorophosphate
    * Results in muscle spasm
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28
Q

Drugs that block transmission at NMJ

A

Curariform drugs: D-tubocurarine

*Prevents AP

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29
Q

Skeletal Muscle Contraction (7)

A
  1. AP travels along motor nerve to NMJ
  2. Nerve secretes ACh, opens ACh-gated channels
  3. Na+ diffuses in, initiates AP
  4. AP travels along muscle membrane, T tubules
  5. AP depolarizes muscle, causing SR to release Ca++
  6. Ca++ initiates actin and myosin sliding
  7. Ca++ pumped back into SR, stopping contraction
30
Q

Walk along/ratchet mechanism (4)

A
  1. Troponin-tropomyosin keeps F-actin inhibited, dec Ca
  2. Ca + troponin C-> conformational change
  3. Power stroke (tilt), release ADP + Pi
  4. New ATP binding detaches myosin head from actin
31
Q

I think it’s the motor nerves that have

A

pre and post ganglionic portions

32
Q

Autonomic Neurotransmitters (2)

A
  1. Acetylcholine

2. Norepinephrine

33
Q

Cholinergic fibers secrete

A

acetylcholine

34
Q

Adrenergic fibers secrete

A

norepinephrine

35
Q

All preganglionic neurons are

A

cholinergic

36
Q

ACh is excitatory to all

A

postganglionic neurons

37
Q

Most parasympathetic postganglionic neurons are

A

cholinergic

38
Q

Most sympathetic postganglionic neurons are

A

adrenergic

39
Q

Acetylcholine receptors (2)

A
  1. Muscarinic - autonomic

2. Nicotinic - somatic

40
Q

Muscarinic Acetylcholine receptors

A

Found on all effector cells stimulated by postganglionic cholinergic neurons of sypathetic or PS systems

41
Q

Nicotinic Acetylcholine receptors (2)

A
  1. Found in autonomic ganglia at synapses between pre- and postganglionic neurons of sympathetic and PS systems
  2. Also present at NMJs
42
Q

Adrenergic receptors

A 
Alpha 1 
- Vasoconstriction
-Smooth muscle contraction
Alpha 2
-Negative feedback on NE
- excitatory?!?!
Beta 1 - excitatory in heart
Beta 2 - inhibitory to smooth muscle (relaxation) Bronchi
43
Q

NE excites mainly

A

alpha adrenergic receptors

44
Q

Epi excites

A

Alpha and Beta receptors about equally

45
Q

Motor neurons (3)

A
  1. Alpha
  2. Gamma
  3. Interneurons
46
Q

Alpha motor neurons (2)

A
  1. Innervates skeletal muscle

2. One alpha nerve fiber excites 3 to hundreds of muscle fibers (motor unit)

47
Q

Gamma motor neurons (2)

A
  1. Transmit impulses through smaller nerves

2. Intrafusal muscle fibers to control muscle tone

48
Q

Interneurons (2)

A
  1. Present in spinal cord gray matter

2. Renshaw cells-lateral inhibition of motor neurons

49
Q

The Lower motor neuron

A

Efferent neuron of the PNS that connects the CNS with the muscle to be innervated

50
Q

General somatic efferent (GSE) (4)

A
  1. Alpha motor neuron
  2. Striated skeletal muscle
  3. All spinal nerves
  4. CN III, IV, I, VI, VII, IX, X, XI, XII
51
Q

General visceral efferent (GVE)

A
  1. Alpha motor neuron
  2. Smooth and cardiac muscle and glands
  3. Sympathetics: all spinal and splanchnic nerves
  4. Parasympathetics: Sacral spinal nerves
  5. CN III, VII, IX, X, XI
52
Q

Wallerian degeneration

A

Something about nerve damage distal to injury or something….

53
Q

Tetanus is a

A

spinal cord dz

54
Q

Nerve root dz

A

Polyradiculoneuritis

55
Q

Nerve disease

A

Polyneuropathies

  • axon
  • myelin
56
Q

Nerve junction diseases (4)

A
  1. Tick paralysis
  2. Botulism
  3. Myasthenia gravis
  4. Snakes
57
Q

Categories of muscle diseases

A
  1. Inflammatory
  2. Infectious
  3. Neoplastic
  4. Snakes
58
Q

F wave evaluates

A

Nerve root-only motor

*only way to eval nerve root!

59
Q

Orthodromic stimulus

A

muscle contraction (M wave)

60
Q

Antidromic stimulus

A

Small, second CMAP called F wave

61
Q

Polyneuropathy DDXs (6)

A
  1. Degenerative
  2. Paraneoplastic
  3. Endocrine
  4. Genetic/heritable
  5. Infectious
  6. Toxic: Vincristine toxicity
62
Q

Vincristine tox (NAVLE)

A
  1. Microtubule modulator
  2. Cumulative toxicity with multiple dosing
  3. Not common
63
Q

Sciatic release

A
  1. Exaggerated patellar
  2. Can’t withdraw
    * lab polyneuropathy thing
64
Q

Endocrine Neuropathies

A
  1. Paraneoplastic-insulinoma
  2. Hypothyroidism-theoretic, not common
  3. Diabetic neuropathy-feline
65
Q

Nerve conduction studies affected by

A
  1. Age
  2. Limb temperature
  3. Limb length
66
Q

Nerve Conduction studies (5)

A
  1. amplitude (strength, proportional to number of axons)
  2. velocity of conduction (speed, reflects degree of myelination)
  3. M wave
  4. Need at least 2-3 points on leg
  5. I think this hurts and we anesthetize dogs
67
Q

Cat’s don’t get megaesophagus because

A

They have smooth muscle in their esophaguses

68
Q

Categories of myopathies (5)

A
  1. Immune mediated
  2. Infectious
    - Neospora caninum
    - Hepatozoon americanum
  3. Preneoplastic
    - lymphoma
  4. Dermatomyositis
  5. Congenital
    - muscular dystrophies
69
Q

Electromyography

A

Healthy muscle is electricaly silen

70
Q

Endocrine myopathies (4)

A
  1. Hypothyroidism-dogs
  2. Hyperthyroidism-cats
  3. Glucocorticoid excess-dogs
  4. Electrolyte derangements
71
Q

Myokymia

A

Looks like worms underskin

-snakebite causes calcium interference on nerve membrane

72
Q

DDX Acute LMN paresis to plegia (6)

A
  1. Polyradiculoneuritis
  2. Tick paralysis
  3. Coral snake envenomation
  4. Mojave rattlesnake in southern cali
  5. Botulism
  6. Fulminant myasthenia gravis

Neuro junior (14 decks)

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