Introduction to Neuropathology- Myopathology Flashcards Preview

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

Flashcards in Introduction to Neuropathology- Myopathology Deck (43):
1

What is an "onion bulb" characteristic of?

segmental demyelination

2

Lost muscle is replaced with _____.

adipose and collagen

3

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

the motor unit

4

What is myopathy?

primary disease of muscle characterized by:

  • proximal weakness
  • elevated CK
  • EMG changes

5

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

histochemical; type 1 or type 2

6

Describe type 1 muscle fibers.

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

7

Which muscle fiber type?

  • more glycolytic enzymes
  • increased rate of fatigue

type 2 (fast-white)

8

What comprises the DAC?

  • dystroglycans (2)
  • sarcoglycans (5)

9

What are the 3 patterns of peripheral neuropathy?

  1. Wallerian degeneration
  2. distal axonopathy
  3. segmental demyelination

10

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

creatine kinase (CK)

11

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

denervation

12

Where do capillaries run in a muscle?

in the endomysium

13

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

slide into each other

14

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

endomysial fibrous and adipose tissue

15

This is the distance btw two z-bands.

a sarcomere

16

What is perineurium?

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

17

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

creatine kinase (CK)

18

_____ filaments are attached to z-bands.

Actin

19

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

myosin and actin

20

Describe type 2 muscle fibers.

  • more glycolytic enzymes
  • increased rate of fatigue

21

What causes distal axonopathy?

  • drugs
  • industrial poisons (pesticides, organic phosphates, solvents)

22

Which muscle fiber type?

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

type 1 (slow-red)

23

What is the motor unit?

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

24

Actin filaments are attached to _____.

z-bands

25

What nerves are most affected by distal axonopathy and why?

large axons bc they have the highest metabolic and nutritional demands

26

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

the nerve supply

27

What is endoneurium?

the small amount of matrix in between individual axons

28

What neuropathies can show segmental demyelination?

  • inflammatory demyelinative neuropathies
  • Charcot-Marie-Tooth disease

29

What causes Wallerian degeneration?

  • trauma
  • peripheral nerve infarction
  • neoplastic infiltration

30

What are the 2 fiber types in muscles?

  1. type 1 (slow-red)
  2. type 2 (fast-white)

31

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

  • dystrophin
  • the dystrophin-associated complex (DAC)

32

What does CK do?

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

33

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

distal axonopathy

34

What is a sarcomere?

the distance btw two Z-bands

35

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

perimysium

36

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

phosphocreatine

37

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

  • myopathy
  • denervation atrophy

38

What is the rate of axonal growth in Wallerian degeneration?

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

39

The immediate source of energy for muscle contraction is ______.

hydrolysis of ATP

40

What is segmental demyelination?

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

41

What is Wallergian degeneration?

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

What is an "onion bulb" formation?

concentric layers of Schwann cell processes and collagen around an axon

43

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

myopathy