Muscle Flashcards
Epimysium
Dense irregular connective tissue- surrounds entire skeletal muscle
Perimysium
Loose connective tissue
-Divides skeletal muscle into fascicles (bundles)
Endomysium
Reticular fibers
surrounds individual skeletal muscle fibers
Striations in skeletal muscle due to
Muofibrils
Regularity of structure of skeletal muscle maintained by
titin
- giant muscle protein
- extends from M line to Z disc
- acts as a passive elastic element
Satellite cells
Play major role in regeneration
-lie btwn basal lamina and sarcolemma of skeletal muscle fibers
increase upon injury and after exercise
Time frame of skeletal muscle regeneration
Activation- 2 hrs
proliferation- 2-3days
restoration- 2 weeks
Other cells that may participate in skeletal muscle regeneration
Muscle derived stem cells bone marrow stem cells blood vessel associated progenitors -mesangioblasts -pericytes
Red fibers Type I
Small diameter high myoglobin content numerous mito fatigue resistant derive energy from ox/phos contract slowly
White fibers Type IIB
greater diameter low myoglobin content fewer mito readily fatigue derive energy from anaerobic glycolysis sudden contraction
intermediate fibers Type IIA
Intermediate size myoglobin content and number of mito
fatigue resistant
Cardiac muscle intercalated discs
Interface btwn adjacent cardiomyocytes
-presence of gap junctions and adhering junctions
functions
- mechanical attachment btwn cells
- transmission of electrical and chemical stimuli
Atrial natriuretic factor (ANF)
released in response to wall stretch
plays are role in regulation of cardiovascular homeostasis by controlling water and electrolyte balance and BP
Purkinje fibers
modified for conduction
found in inter ventricular septum of heart
polymyositis
acute onset begins in adult life
early signs include muscular weakness and tenderness
