Pathology Exam ii
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- Describe denervation atrophy
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Any process that affects anterior horn cells in PNS
manifestation- spinal muscular atrophy - Most common form of denervation atrophy
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Werdnig- Hoffman disease
onset- birth to 4 months, death within 3 years due to muscle atrophy - Describe muscular dystrophies
- inherited disorders, often beginning in childhood, characterized clinically by progressive muscle weakness and wasting. Histologically, muscle fibers replaced by fibrofatty tissue
- Which muscular dystrophy is more severe - DMD or BMD
- DMD
- What is most common type of muscular dystropy
- DMD - 1 per 3500 live male births
- When is DMD clinically manifested
- By age of 5, with weakness leading to wheelchair dependness by age of 10-12,death in early 20's
- Do females have DMD
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Females are carriers, but they are asymptomatic but often have elevated serum creatin kinase.
-females are at risk of developing dilated cardiomyopathy later in life - What is the role of dystrophin in DMD and BMD
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in DMD there is no or minimal dystrophin
in BMD there is abnormal diminished dystrophin - Weakness in DMD begins at
- Pelvic girdle, and progresses to shoulder
- Enlargement of calf muscles associated with weakness in DMD is called
- Pseudohypertrophy - caused by initial increase in muscle fibers and then by replacement with fat and connective tissue
- Which plasma protein is elevated in DMD
- Serum creatin kinase is elevated during first decade of life, and then returns to normal
- Death in DMD results from
- Respiratory insufficiency, pulmonary infection and cardiac decompensation
- Boys with BMD develop symptoms earlier or later then DMD
- Later, with slower progression, and can live normal life span
- Ion channel myopathies
- Group of familial disorders characterized by myotonia, relapsing episodes of hypotonic paralysis(induced by cold, vigorous exercise or high carbohydrate meal)
- Malignant hyperthermia
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Rare clinical symdrome charaterized by dramatic hypermetabolic state - tachycardia, tachypnea, muscle spasms, triggered by induction of anesthesia
Caused by mutation of gene coding for voltage gated Ca channel - Name 3 inflammatory myopathies
- Dermatomyositis, polymyositis, inclusion body myositis
- Dermatomyositis
- Inflammation of both skin and muscle
- Distinctive skin rash in dermatomyositis
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Lilac discoloration of upper eyelids with periorbital edema
Also can be accompanied by Grotton lesions - scaling red eruptions at knuckles, elbows, knees - Muscular involvement in dermatomyositis
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Slow onset
Affects proximal muscles first
Dysphagia
40% correlation with cancer - Polymyositis differs from DM only in
- There is no skin involvement in PM, only proximal muscle involvement
- Inclusion body myositis differs from DM and PM in
- distal muscle involvement, rather then proximal
- Ethanol myopathy
- Binge drinking of alcohol produces acute rhabdomyolysis with accompanying myoglobinuria, which may lead to renal failure
- Drug induced myopathy
- Steroid myopathy, characterized by muscle fiber atrophy, predominantly affecting type II fibers
- Chloroquine myopathy
- Drug originally used to treat malaria can produce myopathy
- Myasthenia Gravis
- Muscle disease caused by immune mediated loss of Ach receptors
- MG prevalence
- 1 in 100 000
- What else is often found in patients with MG
- Thymic hyperplasia in 65% and thymoma in 15 %
- How does MG present clinically
- Ptosis and diplopia (double vision), generalized weakness
- Which drugs are best to treat MG
- Ach esterase inhibitors
- Lambert Eaton syndrome
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Disease of NMJ, paraneoplastic process commonly assoicated with small cell lung CA (60%)
Patients develop proximal muscle weakness along wih autonomic dysfunction - Two processes of repair of tissue damage
- Regeneration and healing
- Definition of regeneration
- Growth of cells and tissue to replace lost structures (liver + kidney)
- Definition of healing
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Response to
-wound
-inflammation
-necrosis - Regeneration requires
- intact connective tissue scaffold
- Cell cycle
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G1 presynthetic
S - DNA synthesis
G2-premitotic
M-mitosis - Labile tissue
- Cells proliferate throughout life, replacing those that are destroyed - surface epithelia - skin, vagina, cervix, lining of glands
- Quiescent (stable) tissue
- low level of replication, but can undergo rapid division under certain stimulus, in G0 but can enter G1 - parenchymal cells of liver, kidney, pancreas, fibroblasts
- Nondividing (permanent) tissue
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Cells that have left cell cycle and cannot undergo mitosis in postnatal period
Neurons, cardiac and skeletal muscle cells - Difference between embryonic and embryonic stem cells
- EMbryonic are pluripotent
- Which growth factor causes migration and proliferation of fibroblasts
- PDGF - platelet deived GF
- Can liver regenerate?
- Yes --> even with 70% removed
- 3 processes of formation of scar
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-emigration and proliferation of fibroblasts
-deposition of ECM
-tissue remodeling - Best example of wound healing by first intention
- surgical incision
- Within 24 hours
- neutrophils appear at the margin, formation of thin epithelial layer
- By day 3
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replacement of neutrophils by macrophages
appearance of granulation tissue
collagen fibers at margins of incision
epithelial proliferation thickens epidermal layer - Day 5
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incisional space is filled with granulation tissue
maximal neovascularization
Abundant collagen fibers
Epidermis recovers normal thickness - 2nd week
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Continued accumulation of collagen and fibroblasts
Increased vasculariy and edema disappear - Month
- Scar has formed, covered by normal epidermis with no inflammation
- Are dermal appendages recover in wound healing
- No, permanently lost
- Healing by 2nd intention
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-more intense inflammatory reaction
-larger amount of granulation tissue
-wound contraction
-scar formation