Muscle PP 1 Flashcards
Sarcomere
Basic contractile unit of a myocyte (muscle fiber)
Sarcoplasm
Cytoplasm of muscle cells
Sarcolemma
Cell membrane of muscle cells
Myofilaments
Made of actin and myosin
Endomysium
Layer of loos CT with fine fibers and capillaries that enclose muscle cells
Fascicles
Bundles where skeletal muscle cells organized
Permysium
Layer of loose CT surrounding each fascicle
To form a muscle, multiple fascicles are enclosed and bound together by a sheath of dense CT known as __________
Epimysium
Type 1 muscle fiber (red)
Slow twitch, fatigue resistant
Rich in myoglobin and mitochondria
Type 2 fibers (white)
Fast twitch, fatigue sensitive
Low myoglobin and mitochondria
CS of muscle disease
Muscle atrophy and hypertrophy
Swelling, weakness, abnormal gait
Muscle spasm
Esophageal dysfunction
What are the 2 main responses to injury?
- Necrosis and regeneration
- Alteration in myofiber size
Hypoplasia
↓ cell number (leading to atrophy)
Loss of motor innervation during development
Degeneration
Only a segment of the myocyte effected
Necrosis
Entire myocyte effected
Lesions associated with muscle disease
Diffuse paleness or streaks in muscle (gross)
Swollen hyalinized, fragmented sarcoplasm, loss of cross striations
+/ - mineralization of sarcoplasm
Histopath lesions associated with muscle disease
Myoglobinemia and myoglobinuria
↑ serum creatine phosphokinase
What causes degeneration and necrosis?
Ischemia
Bacterial toxins and associated hydrolytic enzymes
↑ intra-sarcoplasmic Ca+
Necrosis and regeneration
- Segmental hypercontraction
- Hyaline degradation
- Fragmentation
Cells associated with necrosis and regeneration
Macrophages
Satellite cells activate and undergo mitosis (activated myoblasts)
Proliferating myoblasts for myotubes
Influx of extracellular Ca+
Chalky and white
1. Dystrophic (Ca+ in dead/ dying muscle)
2. Metastatic (metabolic disorders and plants with Vit D)
Cestrum Diurnum (plant)
Affects arteries, tendons and ligaments but not skeletal muscle
Glycoside yields Vit. D3
Solanum Malacoxylon (plants)
Hypervitaminosis D
Tendons arteries and kidney
Atrophy
↓ mass due to fewer and shorter myofilaments
Due to ↓ work load or loss of motor innervation