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52 Cards in this Set

  • Front
  • Back
Type I muscle fibers
- color?
- contraction character?
- major protein
- major cell
- major cell enzyme

Slow twitch (longer, slower contraction)



Mitochondrial enzymes
Type I muscle fibers
- Ability to change size
- Conditioning leads to what?
Don't change in size much with exersize

Increased Aerobic glycolysis
Type II muscle fibers
- color?
- contraction character?
- major molecule
- major cell enzymes x2

Faster, shorter, and more powerful



Enzymes of Embden-Meyerhof pathway (Anaerobic glycolysis)
Type II muscle fibers
- Ability to change size (hypertrophy) with what? x2
- Ability to change size (atrophy) with what? x3
Anabolic steroids or training

Glucocorticoids, disuse or ischemia
Define motor unit and its association with fiber types.
Nerve and all it's innervating muscle fibers

Fiber type is determined by nerve.
What is the role of:
- ATPase (pH 9.4)
- Reverse ATPase (pH 4.3)
Helps demonstrate fiber types
List the common stains used to study muscle problems.
1. ATPase / Reverse ATPase
2. Non-specific esterase
3. NADH-TR (tetrazolium reductase)
4. Alkaline phosphatase
5. PAS
Myotonic Dystrophy would be indicated by what staining test and what would it show?
Abnormal Non-specific esterase
Most frequent atrophy is due to what?
Loss of nerve leading to disintegration of myofibrils,

(small angular fibers with redundant basement membrane)
Small group atrophy is indicative of what? x4
Metabolic abnormality
Early Dystrophy
Fiber splitting (small fibers)
Large group atrophy is indicative of what?
Diagnostic of devervation
In myopathy, what is the non-specific change seen most often?
Fiber splitting
What is characteristically high in myotonic dystrophy?
Internal nuclei
Injury of muscle leads to what pathalogical changes? x3
1. Seepage of muscle protein
2. Hyaline


3. Granular Changes
Regenerating fibers have what pathological changes? x3
1. Large

2. Basophilic

3. Nuclei with prominent nucleoli
Seepage of muscle protein will elevate what?
Creatine Kinase (CK)
List the steps that occur with muscle injury regeneration.
1. Injury

2. Myophagocytosis

3. Regeneration

4. Pan-necrosis healing
Define myophagocytosis.
Macrophages invade the sarcoplasmic membrane and ingest necrotic debris
Regeneration involves what with which cell and structure.
Proliferation of satellite cells and "stubs" of muscle fibers.
Pan necrosis heals by what?
Fibrosis (collagenous scar tissue)
What type of fiber changes are characteristic of myotonic dystrophy?
Ring fibers
What type of fiber changes are characteristic of central core disease?
Core fibers
What type of fiber changes are characteristic of neurogenic diseases.
Target fibers
"Moth-eaten" muscle fibers would be indicative of what?
Vacuoloes would be indicative of what?

- Myopathy x4
- Characteristically seen when?
- Disorders?
Muscular dystrophy
Metabolic myopathy
Toxic myopathy

Periodic paralysis

Storage disorders (glycogen or lipid)
Sarcoplasmic masses and nemaline rods are indicative of what?
Myopathic changes

Non specific
What is seen in large numbers with rod body myopathy?
Nemaline rods
Ragged red fibers are due to what?
Abnormal accumulation of abnormal mitochondria
What happens if UMN knocked out with intact LMN?
Diffuse nonspecific atrophy
Early denervation have what type of fibers?
Target fibers
Describe the response to denervation.
Muscle fibers becomes covered with nicotinic receptors (for ACh)

which will induce nearby nerves to sprout new buds

making contact with the denervated muscle fiber

inducing new synapses.

When new synapse is established, extra receptor fibers will degenerate
What is a general pathognomonic of denervation/reinnervation?
Fiber type grouping
What is a general pathognomonic of denervation?
Large group atrophy
Infantile Spinal Muscular Atrophy

- inheritance
- symptoms
- prognosis
- pathology

Extreme weakness at birth (floppy baby)
Progressive loss of motor function (LMN loss)

Less than 3 years

Small rounded fibers with hypertrophyic type I fibers.
Define muscular dystrophy

Muscle disease
Duchenne's muscular dystrophy would be most severe in what regions?
Pelvic and shoulder
Describe the genetics of Duchenne's muscular dystrophy.
X-linked recessive

Deletion of gene on p arm of X

Results in absence of dystrophin
Compare Duchenne's muscular dystrophy with Becker's muscular dystrophy.
Same gene, different allele

Becker's is less severe

Begins later and slower in progression
Where is dystrophin usually found?
Inner surface of sarcolemma
Function of dystrophin?
Links subsarcolemmal cytoskeleton to glycoprotein-bound laminin.
What is the most common cause of death in patients with Duchenne's?
Respiratory failure

Pulmonary infections

Cardiac arrhythmias (and failure)
Describe the early pathology in Duchenne's. 4
Increased variation if fiber size

Increased internal nuclei

Degeneration, necrosis, myophagocytosis

Brisk regeneration period
Describe the late pathology in Duchenne's. x2
Fibrosis with fibrofatty replacement

and overall muscle atrophy
What is the most common form of muscular dystrophy in adults?
Myotonic dystrophy
Describe the pathogenesis of Myotonic dystrophy. x2

Anticipation with CTG repeats
Clinical feature of myotonic dystrophy

Distal weakness
Pathology of Myotonic dystrophy. x4
Hypertrophy of type II

Atrophy of type I

Internal nuclei numerous

Ring fibers
Congenital myopathy

- clinical signs x3
- test results
- progressiveness
- examples x3
Decreased DTR
Decreased muscle bulk

Normal creatine kinase

Non progressive

Central Core disease
Rod (nemaline) myopathy
Central nuclear mypathy
Central core diseases

- clinical signs x4
- test results
- progressiveness
- genetics
- Pathology x2
Proximal muscle weakness
Decreased DTR
Decreased muscle bulk

Normal creatine kinase

Non progressive

Sporadic, AR, or AD

Type 1 predominance
Central zone degeneration
Rod (nemaline) myopathy

- clinical signs
- associated with?
- test results
- progressiveness
- pathology x2
Proximal limb weakness, face, pharnx, and neck
Decreased DTR
Decreased muscle bulk


Normal creatine kinase

Non progressive

Predominance of Type I
Red and Black rods in cytoplasm
Central Nuclear Myopathy

- inheritance types with signs

- AKA?
X linked - weak & hypotonic (death in neonates)

AD - later onset, slowly progressive

myotubular myopathy
Pathology of Central nuclear myopathy. x3
Type 1 predominance

Central nuclei esp. in type 1 fibers

Fibers small, round, with central nuclei.