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MLSCI 250 > LECTURE - Muscle and PNS > Flashcards

LECTURE - Muscle and PNS Flashcards

1
Q

three types of muscles

A
  • skeletal
  • cardiac
  • smooth
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2
Q

contraction unit of skeletal muscle

A

sarcomere

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3
Q

central core disease

A

ultrastructural disorganization (Z-band streaming)

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4
Q

voluntary control of body movements and sensory

A

somatic

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5
Q

autonomic

A

unconscious control of bodily functions
(heart rate, BP, etc.)
- sympathetic (F or F)
- parasympathetic (R & D)

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6
Q

Pacinian corpuscle

A

an encapsulated ending of a sensory nerve that acts as a receptor for pressure and vibration (skin)

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7
Q

epineurium

A

outermost protective layer = composed of dense connective tissue

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8
Q

perineurium

A

surrounding each individual fascicle (by collagenous tissue w a layer of flat epithelial cells)

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9
Q

endoneurium

A

surrounding individual nerve fiber (by loose vascular supporting tissue)

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10
Q

nerve teasing

A

technique of manually separating axons following osmication
- used to assess segmental demyelination and other myelin abnormalities
- time-intensive due to fragility of axons
TEDIOUS!

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11
Q

T or F. Cardiac muscle cells can regenerate

A

F!

Skeletal muscle cells can due to satellite cells and smooth muscle cells can under special conditions

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12
Q

bone is attached to muscle via

A

tendon

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13
Q

sarcomere structure

A
  • 2 bands, 2 lines, 1 zone
  • bands:
    > anisotropic (dark); myosin
    > isotropic (light); actin
  • lines:
    > Mittelscheibe (middle disc)
    > Zwischenscheibe (intercalated disc)
  • H zone:
    > Heller (bright in German)
    > absent thin filaments
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14
Q

sarcomere disruption

A
  • central core disease

> ultrastructural disorganization (Z-band streaming)

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15
Q

the link between depolarization of the muscle membrane and contraction

A

excitation-contraction coupling

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16
Q

rigor mortis

A

stiffening of the joints and muscles of a body a few hours after death, usually lasting from one to four days

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17
Q

skeletal muscle contraction

A
  • requires ATP to detach myosin head from actin

- rigor mortis occurs if no ATP = no detachment of myosin from actin = stiff muscles

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18
Q

this can be used to select pathological muscle site in difficult cases

A

MRI

19
Q

best specific muscles for biopsy

A

deltoid
biceps
quadriceps

20
Q

selection of muscle to biopsy

A
  • chronic disease: muscle with moderate, but not severe, weakness
  • acute disease: muscle with severe or moderate weakness

AVOId muscles that were site of EMG, injections, or trauma

21
Q

muscle processing technique

A
  • open biopsy procedure
  • do not use cautery, sutures, or clamps
  • needle to minimize trauma (may miss patchy or epimysial pathology)
  • obtain several samples from biopsy site
22
Q

muscle processing transportation

A
  • may be saved in saline moistened gauze for several hrs
  • keep cool
  • should NOT be immersed in saline, fixative, or other liquids
  • adequate dry ice = frozen for shipping ‘overnight’
23
Q

muscle processing preservation

A
  • freeze most tissue in isopentane precooled to -160C in liquid nitrogen
    > freezing process should be rapid to prevent artifact
    > store frozen muscle at -80C
  • fix some muscle in 4% glutaraldehyde
    > embed momst fixd muscle in plastic = for ultrastructural analysis + good visualization of muscle endomysial capillaries
    > paraffin embedded material = useful for surveys for inflammation & morphology of inflammatory cells; gives poor muscle fiber morphology
24
Q

basic panel of stains in muscle biopsy

A
  • Gomori trichrome
  • acid phosphatase: lysosomal activity
  • NADH: mitochondrial activity
  • ATPase: fiber type (differentiates using different pHs)
  • non-specific esterase: denervation
  • COX/SDH: mitochondrial activity
  • PAS/PASD: glycogen
  • oil red O/sudan black: fat

NOTE: many of these are enzyme-based and thus will not work on formalin-fixed paraffin embedded material

25
Q

basic panel of stains in muscle biopsy

A
  • Gomori trichrome
  • acid phosphatase: lysosomal activity
  • NADH: mitochondrial activity
  • ATPase: fiber type (differentiates using different pHs)
  • non-specific esterase: denervation
  • COX/SDH: mitochondrial activity
  • PAS/PASD: glycogen
  • oil red O/sudan black: fat

NOTE: many of these are enzyme-based and thus will not work on formalin-fixed paraffin embedded material

26
Q

nemaline rod myopathy

A

congenital, often hereditary neuromuscular disorder with many symptoms that can occur such as muscle weakness, hypoventilation, swallowing dysfunction, and impaired speech ability

27
Q

T or F. cardiac muscle is not attached to tendon

A

T! attached to each other by intercalated discs

28
Q

T or F. Cardiac muscle only has one cell with one nuclei

A

T! unlike skeletal muscle which has multiple nuclei; this one cannot regenerate; this one has branching connections

29
Q

pacemaker cells

A

sinoatrial cells

- produce depolarization and action potentials to drive cardiac cell contraction

30
Q

voluntary control of body movements and sensory

A

somatic

31
Q

autonomic

A
  • unconscious control of bodily functions (heart rate, BP, etc.)
  • sympathetic = fight or flight
  • parasympathetic = rest + digest
32
Q

peripheral nerve biopsy

A 
- sural nerve most often sampled
 > pure sensory nerve (no motor deficit post-biopsy)
 > easily accessible and identifiable
- superficial peroneal
- superficial radial
33
Q

how should a nerve biopsy arrive

A
  • fresh on saline moist gauze
  • split into three parts:
    > paraffin (FFPE)
    > plastic embedded sections for Toluidine blue sections + electron microscopy
    > teased nerve fibers
34
Q

neurofilament IHC

A

labels axons

35
Q

Bielschosky stain

A

silver stain that stains axons black

36
Q

oligodendrocytes vs Schwann cells

A
  • oligo = myelinates many axons in CNS

- Schwann = myelinates a single axon in PNS

37
Q

Node of Ranvier

A

space between myelin sheath which allows saltatory conduction

38
Q

Masson Trichrome stain (peripheral nerve)

A

stains myelin fuschia

39
Q

Toluidine blue stain for peripheral nerve

A
  • highlights myeline sheath with dark blue staining

- assesses myelination and axonal density and myelin loss

40
Q

types of axons in a peripheral nerve fascicle (3)

A
  • large myelinated axons = fastest conduction
  • small myelinated
  • unmyelinated axons = slowest
41
Q

T or F. pain sensors are myelinated

A

F! they are unmyelinated which is why you feel the heat first and pull way THEN you feel pain; heat sensors (myelinated = faster)

42
Q

an example of demyelinated peripheral neuropathy

A

Guillain-Barre syndrome

43
Q

congo red stain

A
  • for amyloid
  • stains amyloid salmon pink
  • when polarized, shows apple-green birefringence
44
Q

dorsal root ganglia

A

aggregate of sensory neuronal cell bodies

MLSCI 250 (35 decks)

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