LEC-1 Muscle PNS Review

Question 1

What are the three types of muscle?

Answer 1

• Skeletal muscle
• Cardiac muscle
• Smooth muscle

Question 2

What are the characteristics of skeletal muscle?

Answer 2

• Long
• Unbranched
• Multinucleated (peripherally located)
• Striated
• Voluntary

Question 3

What are the characteristics of cardiac muscle?

Answer 3

• Branched
• Intercalated disks
• Central nucleus
• Striated Involuntary (heart)

Question 4

What are the characteristics of smooth muscle?

Answer 4

• Spindle shaped
• One central nucleus
• Not striated
• Involuntary (vessels and gut)

Question 5

What is bursa?

Answer 5

Fluid-filled sacs located in high friction zones such as the shoulder

Question 6

What are the two types of muscle fibers?

Answer 6

• Red
• White

Question 7

Describe red fibers.

Answer 7

• Type 1
• Rich blood supply
• Contain mitochondria and myoglobin
• Slow twitch
• Oxidative
• Sustained contraction (not easily fatigued)

Question 8

Describe white fibers.

Answer 8

• Type 2b
• Poor blood supply
• No mitochondria or myoglobin
• Fast twitch
• Glycolytic (anaerobic glycolysis)
• Easily fatigued

Question 9

Describe intermediate fibers.

Answer 9

• Fast twitch
• Oxidative
• Glycolytic (anaerobic glycolysis)
• Less myoglobin

Question 10

What is a muscle triad?

Answer 10

• Located at A-I junction
• 2 Terminal cisternas+ 1 Transverse tubule

Question 11

The “canister” of a muscle cell is considered to be the ___________.

Answer 11

Myofiber

Question 12

The “straws” inside the canister (myofiber) of a muscle cell are called ____________.

Answer 12

Myofibrils

Question 13

The “toothpicks” inside the the straws (myofibrils) of a muscle cell are called ____________.

Answer 13

Myofilaments

Question 14

The transverse tubule is a continuation of the ______________.

Answer 14

Sarcolemma

Question 15

What are the possible diagnostic tests used to diagnose myofibrillar myopathies?

Answer 15

• Electromyography (EMG)
• Nerve Conduction Study
• Muscle Histology
  
  • Light microscopy
  • Electron microscopy

Question 16

What type of microscopy will expose hyaline inclusions (fibrillar material) within fibers, granulous material, and small vacuoles that result from autophagocytosis of cellular debris?

Answer 16

Light

Question 17

What type of microscopy will reveal myofibril degeneration at Z-discs within muscle fibers?

Answer 17

Electron

Question 18

Label the following diagram:

Answer 18

Label the following diagram:

Question 19

What does the sarcoplasmic reticulum store?

Answer 19

Calcium

Question 20

What happens to the A band during contraction?

Answer 20

It remains the same

Question 21

What happens to the distance between the Z lines during contraction?

Answer 21

It shortens

Question 22

What intermediate filament serves to keep myofibrils in register at Z line?

Answer 22

Desmin

Question 23

What links the α-actinin/desmin complex to plasma membrane dystroglycans?

Answer 23

Dystrophin

Question 24

What are gap junctions?

Answer 24

Specialized channels used in smooth muscle to ensure coordinated contraction. These channels allow electrical impulses to pass more quickly to adjacent cells through a shared perforation in cell membrane.

Question 25

What are gap junctions in cardiac muscles called?

Answer 25

Intercalated discs

Question 26

What is a motor unit?

Answer 26

A motor unit is a nerve and the myofibers it innervates.

Question 27

What epithelial layer of a peripheral nerve is affected in Guillan-Barre Syndrome?

Answer 27

Endoneurium

Question 28

What epithelial layer of a peripheral nerve must be sutured in surgery?

Answer 28

Perineurium

Question 29

What are the three layers of connective tissue covering skeletal muscle fibers?

Answer 29

* Epimysium (outermost layer) * Perimysium (intermediate layer; found between each fascicle) * Endomysium (innermost layer; found between each myofiber)

Question 30

What is the defect in Lambert-Eaton Syndrome?

Answer 30

Voltage-gated Calcium channels on pre-synaptic cell

Question 31

What is the defect in Myasthenia Gravis and what is the result?

Answer 31

Antibodies towars ACh receptors on the post-synaptic cell Results in loss of junctional folds

Question 32

What happens to intrafusal fibers when an extrafusal fiber contracts?

Answer 32

It loses tension and compensates by shortening

Question 33

(Schwann cells/Oligodendrocytes) are located in the PNS.

Answer 33

Schwann cells

Question 34

(Schwann cells/Oligodendrocytes) are located in the CNS.

Answer 34

Oligodendrocytes

Question 35

(Schwann cells/Oligodendrocytes) provide myelin for up to 50 axons at once.

Answer 35

Oligodendrocytes

Question 36

(Schwann cells/Oligodendrocytes) provide myelin for only a single axon at a time.

Answer 36

Schwann cells

Question 37

Guillain Barre syndrome may indicate pathology involving (schwann cells/oligodendrocytes).

Answer 37

Schwann cells

Question 38

An acoustic neuroma may indicate pathology involving (schwann cells/oligodendrocytes).

Answer 38

Schwann cells * Acoustic neuromas are also called schwannomas

Question 39

Multiple sclerosis may indicate pathology involving (schwann cells/oligodendrocytes).

Answer 39

Oligodendrocytes

Question 40

(Merkel's discs/Meissner's corpuscles) adapt quickly, are found in hairy skin, and are used to detect shapes and edges.

Answer 40

Merkel's discs

Question 41

(Merkel's discs/Meissner's corpuscles) adapt slowly, are found in glabrous skin, and are used to detect light touch.

Answer 41

Meissner's corpuscles

Question 42

In a (neuropathy/myopathy), innervation is intact and weakness is proximal and symmetrical. May result from atrophy caused by aging, malnutrition, or immobilization.

Answer 42

Myopathy

Question 43

In a (neuropathy/myopathy), innervation is lost and weakness is distal and asymmetrical. May result from atrophy caused by motor neuron degeneration.

Answer 43

Neuropathy

Question 44

What is the afferent and efferent limb of the muscle spindle organ (deep tendon reflex)?

Answer 44

* Afferent: Ia and II fibers * Efferent: Gamma motor neurons

Question 45

What are Pacinian Corpuscles sensitive to?

Answer 45

Vibration Pressure