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aNeuro Exam I- Lindsey's > Introduction to Neuropathology- Myopathology > Flashcards

Introduction to Neuropathology- Myopathology Flashcards

1
Q

What is an “onion bulb” characteristic of?

A

segmental demyelination

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2
Q

Lost muscle is replaced with _____.

A

adipose and collagen

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3
Q

This is a group of 100-200 myofibers all innervated by the same motor neuron.

A

the motor unit

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4
Q

What is myopathy?

A

primary disease of muscle characterized by:

  • proximal weakness
  • elevated CK
  • EMG changes
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5
Q

All fibers in a motor unit are of the same ______ type, either _____ or ______.

A

histochemical; type 1 or type 2

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6
Q

Describe type 1 muscle fibers.

A
  • more oxidative enzymes
  • more mitochondria
  • more myoglobin
  • increased tonic firing
  • decreased rate of contraction and relaxation
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7
Q

Which muscle fiber type?

  • more glycolytic enzymes
  • increased rate of fatigue
A

type 2 (fast-white)

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8
Q

What comprises the DAC?

A
  • dystroglycans (2)
  • sarcoglycans (5)
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9
Q

What are the 3 patterns of peripheral neuropathy?

A
  1. Wallerian degeneration
  2. distal axonopathy
  3. segmental demyelination
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10
Q

This is an enzyme that moves phosphate from creatine phosphate to ADP.

A

creatine kinase (CK)

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11
Q

This is distal weakness and atrophy with normal CK and different EMG changes.

A

denervation

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12
Q

Where do capillaries run in a muscle?

A

in the endomysium

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13
Q

During contraction, actin and myosin _____ to shorten the sarcomere by 20%.

A

slide into each other

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14
Q

In muscular dystrophy, _____ increase and replace lost muscle, also causing stiffness.

A

endomysial fibrous and adipose tissue

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15
Q

This is the distance btw two z-bands.

A

a sarcomere

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16
Q

What is perineurium?

A

a sheath of special, fiber-like cells that tie the axons of each fascicle together

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17
Q

When the sarcolemma is damaged, _____ leaks into the serum.

A

creatine kinase (CK)

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18
Q

_____ filaments are attached to z-bands.

A

Actin

19
Q

Myofibers contain 2 kinds of contractile filaments: ____ and _____.

A

myosin and actin

20
Q

Describe type 2 muscle fibers.

A
  • more glycolytic enzymes
  • increased rate of fatigue
21
Q

What causes distal axonopathy?

A
  • drugs
  • industrial poisons (pesticides, organic phosphates, solvents)
22
Q

Which muscle fiber type?

  • more oxidative enzymes
  • more mitochondria
  • more myoglobin
  • increased tonic firing
  • decreased rate of contraction and relaxation
A

type 1 (slow-red)

23
Q

What is the motor unit?

A

group of 100-200 myofibers all innervated by the same motor neuron

24
Q

Actin filaments are attached to _____.

A

z-bands

25
Q

What nerves are most affected by distal axonopathy and why?

A

large axons bc they have the highest metabolic and nutritional demands

26
Q

What determines if the fibers in a motor unit are type 1 or type 2?

A

the nerve supply

27
Q

What is endoneurium?

A

the small amount of matrix in between individual axons

28
Q

What neuropathies can show segmental demyelination?

A
  • inflammatory demyelinative neuropathies
  • Charcot-Marie-Tooth disease
29
Q

What causes Wallerian degeneration?

A
  • trauma
  • peripheral nerve infarction
  • neoplastic infiltration
30
Q

What are the 2 fiber types in muscles?

A
  1. type 1 (slow-red)
  2. type 2 (fast-white)
31
Q

Myofibers are bound to the extracellular matrix by chain of proteins consisting of ____ and ______.

A
  • dystrophin
  • the dystrophin-associated complex (DAC)
32
Q

What does CK do?

A

it’s an enzyme that moves phosphate from creatine phosphate to ADP

33
Q

In _____, degeneration of the axon and myelin develops first in the most distal parts of the axon.

A

distal axonopathy

34
Q

What is a sarcomere?

A

the distance btw two Z-bands

35
Q

Each muscle is wrapped by a fibrocollagenous sheath called the ______.

A

perimysium

36
Q

What is the other source of energy that isn’t used for muscle contraction, but to replenish ATP?

A

phosphocreatine

37
Q

Muscle disease can be placed into 2 broad categories: _____ and _____.

A
  • myopathy
  • denervation atrophy
38
Q

What is the rate of axonal growth in Wallerian degeneration?

A

1-2 mm/day (faster if closer to the cell body)

39
Q

The immediate source of energy for muscle contraction is ______.

A

hydrolysis of ATP

40
Q

What is segmental demyelination?

A

the breakdown and loss of myelin over a few segments, but the axons remain intact and the neuronal body doesn’t change

41
Q

What is Wallergian degeneration?

A

an axon is transected and central chromatolysis occurs (smooth cytoplasm, displaced nucleus) to disintegrate and degrade the old axon and grow a new one from the proximal stump

42
Q

What is an “onion bulb” formation?

A

concentric layers of Schwann cell processes and collagen around an axon

43
Q

This is primary disease of muscle characterized by proximal weakness, elevated CK, and EMG changes.

A

myopathy

aNeuro Exam I- Lindsey's (26 decks)

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