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22 fall: path > Test 4: 1: skeletal PNS > Flashcards

Test 4: 1: skeletal PNS Flashcards

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1
Q

muscle cell make up

A

myofilaments (actin and myosin) form together to make

myofibril, a bunch of myofibrils form together to make

myofiber/muscle cell surrounded by endomysium, many group together to make

fascicles surrounded by perimysium, many to form muscle surround by epimysium

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2
Q

myofibril surrounded by —
Fascicles surrounded by —
muscle surrounded by —

A

endomysium
perimysium
epimysium

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3
Q

— are cells in muscles that cen divide and reform mature myofibers

A

satellite cell

live between in the plasma membrane and the basal lamina

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4
Q

motor unit makes up

A

motor neuron and all of the myofibers(muscle cells) it innervates

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5
Q

Motor neuron releases —from
synaptic vesicles to trigger muscle contraction

A

acetylcholine

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6
Q

what are some blood values that indicate muscle damage

A

Creatinine kinase (CK)
* Lactate dehydrogenase (LDH)
* Aspartate aminotransferase (AST)
* Alanine aminotransferase (ALT)

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7
Q

— is the Loss of myofilaments (actin & myosin) causing the myofibers (muscle
cells) to decrease in size

A

atrophy

decrease in diameter of entire muscle and individual myofibers

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8
Q

3 common causes of atrophy

A

denervation
disuse
malnutrition

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9
Q

denervation is loss of connection with –

A

peripheral nerves

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10
Q

— type of atrophy Leads to patchwork myofiber atrophy

A

denervation

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11
Q

why type of muscle atrophy does not show muscle regeneration?

A

denervation

disuse

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12
Q

common causes of muscle atrophy denervation

A

Wallerian degeneration
* Secondary to trauma to the peripheral nerve

Axonal degeneration

Demyelination (rare)

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13
Q

— cells proliferate at the motor end plate of the denervated fiber to cause reinnervation after wallerian degeneration

A

Schwann cell

caused by collateral sprouting or axon regrowth

hypertrophy with increase in myofibrils

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14
Q

disuse atrophy is due to — mechanical load leading to — atrophy

A

low
diffuse

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15
Q

disuse atrophy activates the — pathways

A

catabolic

-cage rest, cast ect.

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16
Q

what can cause hypertrophy of muscle cells

A

increased workload

compensatory hypertrophy- cells increase in size to make up for the loss of other myofibers

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17
Q

degeneration of muscle fibers cause —

A

multifocal/regional hydropic swelling and fatty changes

reversible but can lead to necrosis

can be caused by toxins

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18
Q
A

muscle necrosis

Loss of striations and hypereosinophilic cytoplasm

Inflammatory cells infiltrate within 24-48 hours
* Macrophages and neutrophils clean up debris

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19
Q

necrosis of muscle cell causes loss of — and — cytoplasm

A

striations

hypereosinophilic

inflammatory cells come in and clean up
satellite cells start regeneration

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20
Q

necrosis with intact basal lamina leads to –

necrosis with destroyed basal lamina lead to —

A

regeneration

fibrosis

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21
Q

— will fuse together to make new myofiber

A

satellite

basal lamina needs to be intact for regeneration to occur

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22
Q

metastatic mineralization is caused by

A

excess Vit D

vit D toxicity
hyperparathyrodism

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23
Q

dystrophic mineralization is caused by

A

necrosis

dead cell can’t control how calcium comes into cell

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24
Q

Fibrodysplasia ossificans progressiva in cats causes —

A

mineralization of skeletal muscle leading to bone formation

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25
X-linked muscular dystrophy is caused by mutation in --- that lead to ---
dystrophin dystrophin needed to anchor muscle cell membranes to basement membrane without this, cells undergo necrosis, mineralization and fibrosis
26
x linked musclar dystrophy attacks --- muscle
skeletal and cardiac ## Footnote mutation in anchoring gene dystrophin
27
what are some symptoms of x linked muscular dystrophy
Golden retrievers, Rottweilers * Diffuse muscle atrophy, splaying of limbs, weakness ## Footnote x linked in dogs and cats autosomal recessive in sheep
28
two possible causes of equine extertional ehabdomyolysis
oxidative damage from vit E or selenium deficiency Metabolic/electrolyte imbalance (hypokalemia- low potassium)
29
--- in horses is triggered by exercise and leads to acute myofiber necrosis
equine extertional rhabdomyolysis ## Footnote vitE or selenium deficiency Metabolic/electrolyte imbalance (hypokalemia)
30
Diet change to one high in --- and low in --- improves clinical signs in many horses (with or without EPSSM) | Equine Polysaccharide Storage Myopathy
fat and fiber starches and sugars ## Footnote Some horses with Equine Polysaccharide Storage Myopathy demonstrate exertional rhabdomyolysis
31
Eq uine Exertional Rhabdomyolysis causes marked elevation in --- and ---, ---uria and acute ---
CK and AST myoglobinuria- pigmented urine renal failure
32
symptoms of equine Exertional Rhabdomyolysis
Sudden onset of stiff gait, reluctance to move, pain and discomfort, +/- swelling of affected muscles * Not always associated with exhaustive exercis ## Footnote Affected muscles: gluteal, femoral, and lumbar groups
33
difference between histo of Equine Exertional Rhabdomyolysis and Equine Polysaccharide Storage Myopathy
exertional- necrosis poly- degeneration of myofibers
34
some horses with Equine Polysaccharide Storage Myopathy have a mutation in
skeletal muscle glycogen synthase 1 (GYS1)
35
what kind of stain for Equine Polysaccharide Storage Myopathy
PAS makes polysaccharides dark red
36
masticatory myositis effects what kind of dogs
Young large breed dogs predisposed (German shepherds, Rottweilers)
37
Masticatory myositis is caused by autoantibodies to
Type 2M myosin isotype and myositigen (myosin- binding protein)
38
masticatory myositis attacks what muscles
muscles used to chew (masseter, temporal, and pterygoid) ## Footnote caused by autoantibodies to Type 2M myosin autoimmune
39
what do you see on histo of masticatory myositis
Multifocal, polyphasic necrosis with inflammation * Lymphocytic and **eosinophilic** inflammation ## Footnote autoimmune autoantibodies to Type 2M myosin isotype
40
what breed of dogs get polymyositis
Adult dogs of various breeds * Young Newfoundlands and Boxers | autoimmune ## Footnote Affected dogs do not have antibodies to type 2M myosin * BUT serum autoantibodies bind to unidentified sarcolemmal antigen
41
symptoms of polymyositis of dogs
Variable clinical signs depending on muscles affected * Overall muscle weakness, stiff gate, muscle atrophy, regurgitation, +/- pain * Paraneoplastic syndrome with thymoma ## Footnote unknown autoimmune disorder- NOT type 2M myosin (Masticatory myositis)
42
Extraocular muscle myositis RARE not painful effects young female golden retrievers unknown cause histo- Multifocal polyphasic necrosis with lymphocytic inflammation of the **extraocular rectus and oblique muscles** ## Footnote autoimmune
43
--- effects the extraocular rectus and oblique muscles of young female golden retrievers
Extraocular muscle myositis rare, unknown cause ## Footnote autoimmune
44
Immune mediated myositis of horses is associated with --- bacteria
Streptococcus equi– associated purpura hemorrhagica ## Footnote immune response to immune complexes of IgA and strep M proteins cause hemorrhagic necrosis of muscle due to vascular injury
45
blood work of immune mediated myositis of horses will show
Immune-complexes of IgA and streptococcal M protein Markedly increased CK and AST and muscle weakness and pain ## Footnote caused by immune response to strep equi infection
46
histo of immune mediated myosistis of horses will ---
Vasculitis and fibrinoid necrosis of vascular walls with hemorrhagic infarcts within affected muscles * Inflammatory infiltrates not seen within muscle ## Footnote caused by immune response to immune complexes of IgA and strep equi M protein
47
benign or malignant rhabdomyoma
benign rare common in larynx of young dogs can cause respiratory distress depending on position of tumor
48
embryonal, botryoid and alveolar rhabdomyosarcoma occur in --- dogs and are found where in the body
young NOT extremities- bladder, tongue and face
49
infiltrative lipoma benign but can be difficult to remove
50
axons are surrounded by --- fascicles are surrounded by --- surrounds nerves
endoneurium perineurium epineurium (contiguous with the dura mater)
51
--- cells myelinates axons of nerves
schwann cells also help with regeneration
52
endoneurial fibroblasts make --- and act as ---
collagen phagocytes (during axon damage)
53
the blood nerve barrier is made of
Tight junctions of endoneurial blood vessels Perineurium (surrounds nerve fasicle and contains blood vessels) * Regulated movement of substances from blood to endonerium NOT very strong barrier
54
wallerian degeneration
55
what causes wallerian degeneration
trauma or compression of axon leading to loss of distal segment leads to build up of proteins, debris and neurofilamatent and **chromatolysis** of the neural cell body, as well as **spheroid** formation chromatolysis can be resolved if axon reattaches/fixes itslef
56
swelling of degenerating axon is called
spheroid Anterograde and retrograde axonal flow is halted → accumulations of neurofilaments, mitochondria and debris happens with wallerian degeneration
57
if endoneurial sheath is intact what will happen to axon after wallerian degeneration
Axonal sprouting and segmental remyelination of the proximal axonal spheroid stump by Schwann cells (regrows and reestablishes neuromuscular junction)
58
successful regeneration on the PNS depends on
* Intact endoneurium * Site of injury: more distal lesions (farther from cell body) = better recovery * Distance between severed ends: closer = better recovery * Amount of damage and debris at injury site: less injury and debris = better recovery
59
The time course of Wallerian degeneration varies in the peripheral (---) and central (---) nervous systems.
faster slower
60
some causes of axonal degeneration
**Inherited**: Degenerative myelopathy **Metabolic**: Peripheral neuropathy associated with diabetes (hypothyroidism, hypoglycemia, insulinoma) * Diabetes: distal axonopathy with degeneration/demyelination & regeneration/remyelination likely due to impairment of axonal transport secondary to decreased glucose **Toxic**: plant toxins, metals (lead, arsenic, mercury), organophosphates * Karwinol Toxin from fruit seeds of coyotillo shrub (Karwinskia humboldtiana) * Small ruminants in southwestern US * Induces direct axonal injury and subsequent demyelination in peripheral axons (and CNS, too) * Subsequent denervation atrophy of skeletal muscle
61
--- is Metabolic derangement of the entire neuron
axonal degeneration myelin sheath breaks down at same time (looks similar to wallerian degeneration) caused by inherited, metabolic or toxic diseases
62
segmental demyelination if usually caused by
toxin can be inflammatory, or compression ## Footnote loss of myelin sheath leaving an intact bare axon
63
Polyneuritis equi (Cauda Equina Syndrome) is caused by
unknown but maybe immune mediated
64
symptoms of Polyneuritis equi (Cauda Equina Syndrome)
ataxia, pain, dropped tail, urinary incontinence, fecal retention and muscle loss * Nerve roots are thickened and fusiform and usually discolored yellow * Granulomatous inflammation and abundant fibrosis
65
histo of cauda equina syndrome (polyneuritis equi)
inflammation inside and around nerves with areas of fibrosis Nodular aggregates of granulomatous inflammation surrounding nerves at the nerve roots Expansion of perineurium and epineurium by fibrosis
66
aquired myasthenia gravis is caused by
Auto-antibodies to **acetylcoline receptors** and blocks function prevents contraction of muscle treat with anti-acetylcholinesterase therapy (flood area with AcH)
67
how to treat acquired myasthenia gravis
anti-acetylcholinesterase therapy (flood area with AcH by preventing enzyme that breaks down AcH)
68
congenital myasthenia gravis is caused by --- in --- dogs
decreased number of ACh receptors Jack Russell terriers, springer spaniels, smooth haired fox terriers treat will anti-cholinesterase therapy
69
how does botulism work
Clostridium botulinum releases toxin that enters neuron and prevents release of acetylcholine leading to **flaccid paralysis**
70
how does tetanus work
Clostridium tetani Tetanospasmin travels retrograde along peripheral nerves and preferentially binds to **inhibitory interneurons** prevents release of **inhibitory neurotransmitter** leading to **spastic/rigid paralysis**
71
what causes tetanus
Clostridium tetani * Ubiquitous G+ spore-forming anaerobe in soil
72
--- causes flaccid paralysis --- causes rigid paralysis
botulism tetanus
73
Equine Laryngeal hemiplegia Progressive degeneration of axons of left recurrent laryngeal nerve leads to airway obstruction and stridor
74
some causes of Equine Laryngeal hemiplegia
Trauma to the nerve Extension of inflammation from the guttural pouches → transection of axon Congenital axonal transport defect? ## Footnote degeneration of axons of left recurrent laryngeal nerve
75
peripheral nerve sheath tumors originate from
Schwann cells, fibroblasts, or perineural cells **Schwannomas** (Schwann cells) - most common in dog (also cat, horse, cattle) **Perineuriomas** (perineurial cells) – reported in cattle **Neurofibroma** (Schwann cells and perineurial fibroblasts) – reported in dogs
76
--- tumors have no widely accepted grading scheme to distinguish benign from malignant
(Peripheral) Nerve sheath tumors Malignant tumors = more anaplastic features, high mitotic index, presence of necrosis, aggressive local growth and invasion into adjacent normal tissue, and potential for metastasis

22 fall: path (46 decks)

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