Muscle PP 1 Flashcards

1
Q

Sarcomere

A

Basic contractile unit of a myocyte (muscle fiber)

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2
Q

Sarcoplasm

A

Cytoplasm of muscle cells

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3
Q

Sarcolemma

A

Cell membrane of muscle cells

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4
Q

Myofilaments

A

Made of actin and myosin

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5
Q

Endomysium

A

Layer of loos CT with fine fibers and capillaries that enclose muscle cells

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6
Q

Fascicles

A

Bundles where skeletal muscle cells organized

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7
Q

Permysium

A

Layer of loose CT surrounding each fascicle

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8
Q

To form a muscle, multiple fascicles are enclosed and bound together by a sheath of dense CT known as __________

A

Epimysium

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9
Q

Type 1 muscle fiber (red)

A

Slow twitch, fatigue resistant
Rich in myoglobin and mitochondria

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10
Q

Type 2 fibers (white)

A

Fast twitch, fatigue sensitive
Low myoglobin and mitochondria

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11
Q

CS of muscle disease

A

Muscle atrophy and hypertrophy
Swelling, weakness, abnormal gait
Muscle spasm
Esophageal dysfunction

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12
Q

What are the 2 main responses to injury?

A
  1. Necrosis and regeneration
  2. Alteration in myofiber size
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13
Q

Hypoplasia

A

↓ cell number (leading to atrophy)
Loss of motor innervation during development

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14
Q

Degeneration

A

Only a segment of the myocyte effected

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15
Q

Necrosis

A

Entire myocyte effected

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16
Q

Lesions associated with muscle disease

A

Diffuse paleness or streaks in muscle (gross)
Swollen hyalinized, fragmented sarcoplasm, loss of cross striations
+/ - mineralization of sarcoplasm

17
Q

Histopath lesions associated with muscle disease

A

Myoglobinemia and myoglobinuria
↑ serum creatine phosphokinase

18
Q

What causes degeneration and necrosis?

A

Ischemia
Bacterial toxins and associated hydrolytic enzymes
↑ intra-sarcoplasmic Ca+

19
Q

Necrosis and regeneration

A
  1. Segmental hypercontraction
  2. Hyaline degradation
  3. Fragmentation
20
Q

Cells associated with necrosis and regeneration

A

Macrophages
Satellite cells activate and undergo mitosis (activated myoblasts)
Proliferating myoblasts for myotubes

21
Q

Influx of extracellular Ca+

A

Chalky and white
1. Dystrophic (Ca+ in dead/ dying muscle)
2. Metastatic (metabolic disorders and plants with Vit D)

22
Q

Cestrum Diurnum (plant)

A

Affects arteries, tendons and ligaments but not skeletal muscle
Glycoside yields Vit. D3

23
Q

Solanum Malacoxylon (plants)

A

Hypervitaminosis D
Tendons arteries and kidney

24
Q

Atrophy

A

↓ mass due to fewer and shorter myofilaments
Due to ↓ work load or loss of motor innervation

25
Physiologic causes of atrophy
Disuse, cachexia, and aging
26
Endocrine based atrophy
Most common in dogs: hypothyroidism, hyperadrenocorticism Equine's cushings (PPID)
27
Denervation atrophy
Equine laryngeal hemiplegia (left recurrent laryngeal nerve)
28
Hypertrophy
↑ mass due to sarcomeres (cell size) Due to ↑ workload ↑ volume and weight
29
Degenerative diseases of muscle
Trauma → ischemia Leads to muscle damage and neuropathy ex: downer cows
30
Muscular Dystrophy
Inherited progressive myodegeneration and myonecrosis Defective dystophin gene
31
Malignant hyperthermia
Inherited defect in Ca-gating regulation → uncontrolled release of Ca from sarcoplasmic reticulum Acute myodegeneration and myonecrosis Triggered by stress, halothane anesthesia
32
Other names for malignant hyperthermia
Porcine stress syndrom or Pale soft exudative pork
33
CS with malignant hyperthermia
Normal until triggered Severe muscle rigidity and ↑ body temperature Muscles pale pink moist, swollen with cooked appearance Pulmonary edema Rapid autolysis
34
Neuromuscular dysregulation
MG Acquired: destroys ACh receptors on myocyte Inherited: inadequate # of ACh receptors
35
Steatosis (lipomastosis)
Replacement of muscle tissue by adipose tissue Common in fattened pigs No CS, found @ slaughter