Anatomy and embryology of skeletal muscle Flashcards
Function of skeletal muscle
Force generation for breathing and movement
Force generation for postural support (helping you stand up)
Heat generation (shivering)
Metabolism (AA reservoir)
Describe the types of muscle
Skeletal - striated, multinucleate, unbranched; somatic nervous system
Cardiac - striated, branched, has intercalated discs; autonomic nervous system
Smooth - spindle shaped cells, non-striated; autonomic nervous system
Syncytial meaning
Giant multinucleate cell
Describe tendons
Made of type I collagen; connects bone to muscle - transfers muscle force to bone
What are the two main types of muscle contraction?
Isotonic (muscle length changes with force production)
Isometric (muscle length doesn’t change with force production)
What are the types of isotonic muscle contraction?
Concentric = muscles shorted during contraction Eccentric = muscle produces a force but length increases (bicep when controlling lowering of a weight)
Prime mover
Agonist - concentric contraction
Antagonist
Opposes the action of prime mover
Fixator
Steadies position through isometric contraction (lumbar muscles)
Synergist
Complements action of prime mover
Describe the structure of a muscle bundle
Epimysium = outermost layer (tough) that surrounds entire muscle Perimysium = surrounds bundles of muscle fibres, creates a fascicle Endomysium = surrounds muscle fibres
Formation of skeletal muscle
Myoblasts undergo proliferation when encouraged by growth factors; then when growth factors are removed they fuse into a myotube (muscle fibre)
Describe satellite cells
Stem cells which are mitotically quiescent, can be encouraged to enter the cell cycle to form myoblasts; self renewing so can replace themselves.
What are satellite cells important for?
Muscle growth after birth;
Muscle maintenance;
Muscle hypertrophy + repair, regeneration
What can effect the speed of contraction of a muscle
The myosin heavy isoform present in the sarcomere
