muscle tissue

• muscle cells = muscle fibres = myofibres = myocytes
• epimysium

  DICT surrounds whole muscle
• perimysium

  DICT surrounds fascicles
• fascicle

  group of muscle cells
• endomysium

  LCT, surrounds individual muscle cells
• development of skeletal muscle

  myoblast, fusion, immature muscle fibres, differentiation
• skeletal muscle

  striations, multi nucleated, peripheral nuclei
• cytoplasm of skeletal muscle is filled with myofibrils
• myfibrils contain sarcomere
• sarcomres contain myofilaments
• thick filaments

  myosin
• thin filaments


  actin
• skeletal muscle stains acidophilic
• sarcomere runs from z disc to z disc
• z disc bisects I band
• I band

  contains only thin filament
• M line

  middle of sarcomere, where thick filaments are attached
• A band

  region of sarcomere with thick filaments
• H zone

  in middle of A band, region of thick filament that has no overlap with thin filament
• stems attach at M line in thick filament
• tropomyosin and troponin bind to actin
• sarcoplasmic reticulum

  sER surrouding each myfibril, regulates intracellular calcium levels
• transverse tubules

  invaginations of cell membrane, carries action potential from outside to inside
• thick filaments power contraction, thin filaments are pulled towards M line, shortening sarcomere
• cardiac muscle

  one or 2 central nuclei, striated, cells branch, intercalated discs
• cardiac muscle is innervated by the autonomic nervous system
• skeletal muscle is innervated by the somatic nervous system
• intercalated discs

  contain adhering and communicating junction
• cardiac muscle cytoplasm

  50% is mitochondria, lots of capillaries
• cardiac cells

  less sarcoplasmic reticulum, t tubules, diads, extensive blood supply
• desmosomes in cardiac muscles

  vertical composition
• gap junctions in cardiac muscles

  horizontal composition
• smooth muscle

  one central nuclei, fusiform, no striations, cell junctions
• smooth muscle is innervated by the autonomic nervous system
• actin is anchored to dense bodies
• each smooth cell is surrounded by endomysium
• smooth muscle cells

  thin, short, little sarcoplasmic reticulum, no sarcomeres, myofibrils, or T tubules, may have caveolae
• caveolae

  calcium homeostasis and contraction signalling
• energy from hydrolysis of ATP is transferred to mechanical energy
• CT transmits force to bones to move joints and to other muscle cells and CT to act as one tissue