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| − | ===Response to injury===
| + | {{toplink |
| − | | + | |backcolour =CDE472 |
| − | *Limited array of ways in which to respond to injury
| + | |linkpage =Musculoskeletal System - Pathology |
| − | **[[:Category:Muscles - Degenerative Pathology|Degeneration]]
| + | |linktext =Musculoskeletal System |
| − | **[[Muscle Necrosis|Necrosis]]
| + | |maplink = Musculoskeletal System (Content Map) - Pathology |
| − | **Regeneration
| + | |pagetype =Pathology |
| − | **[[Muscle Atrophy|Atrophy]]
| + | |sublink1=Muscles - Pathology |
| − | **[[Muscle Hypertrophy|Hypertrophy]]
| + | |subtext1=MUSCLES |
| − | | + | }} |
| − | *Large number of factors indicing the changes above, e.g.:
| + | <br> |
| − | **Trauma
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| − | **Toxins
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| − | **Infectious agents
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| − | **Nutritional deficiencies
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| − | **Ichaemia
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| − | **[[:Category:Muscles - Developmental Pathology|Hereditary diseases]]
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| − | *Specific diagnosis is often not possible based on morphological or histological features alone
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| − | *Additional tests, clinical information and history are often required
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| − | ===Regeneration===
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| − | [[Image:Muscle regeneration.jpg|right|thumb|100px|<small><center>Muscle regeneration (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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| − | *Skeletal muscle myofibres have substantial regenerative ability
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| − | *Success depends on:
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| − | **An intact '''sarcolemmal tube''' - to act as a support and guide
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| − | **Availability of '''satellite cells''' - to act as progenitor cells for new sarcoplasm production
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| − | **Macrophages to clear up cell debris
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| − | **If these conditions are not met (e.g. severe thermal damage) '''fibrosis''' will occur
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| − | *Stages:
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| − | #Nuclei in [[Muscle Necrosis|necrotic segement]] disappear, hyalinased sarcoplasm due to loss of normal myofibrillar structure, may separate from adjacent normal myofibrils and/or [[Muscle Calcification|mineralise]]
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| − | #Monocytes from capillaries -> macrophages in necrotic portion, satellite cells swell -> vesicular with prominent nucleoli -> mitosis (within 1-4 days after initial injury)
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| − | #Satellite cells move to centre
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| − | #Macrophages clear the sacrolemmal tube, plasmalemma disappears, shape maintained by basal lamina
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| − | #Satellite cells -> myoblasts (contain myosin) -> fuse forming myotubes with row of central nuclei; cytoplasmic processes fusing
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| − | #Growing and differentiating fibre, striations appear - formation of sarcomeres
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| − | #Nuclei move to peripheral position (2-3 weeks after initial injury)
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| − | *Regeneration by '''budding'''
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| − | **When conditions are not optimal, disrupted sacrolemma
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| − | **E.g. injection of irritating substance, trauma, [[Muscle Ischaemia|infarction]]
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| − | **Myoblasts proliferate -> sacrolamma bulges from cut part -> club-shaped with numerous central nuclei = muscle giant cells
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| − | *Monophasic lesions - all at same phase above
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| − | [[Category:Muscles - Pathology]]
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