5. Skeletal muscle Flashcards
Why do striations arise
myofibrils held in register by intermediate filaments that link Z discs (desmin) laterally and longitudinally
function of intermediate filament network
prevent over stretching and allow force transmitted laterally and longitudinally
where is the nuclei
on side to give space for myofibril
how is calcium stored in SR
binding with protein calsequestin
desmin fibres
non-myofibrillar cytoskeleton provide links to BM and surrounding connective tissue
Endomysium
loose connective tissue
surrounds each muscle fibre
connects to BM
Perimysium
mix of loose and dense connective tissue
surrounds each muscle fascicle
main venue for nerves and vessels
epimysium
loose connective tissue between fascia and muscle body
fascia
dense layer of connective tissue covering muscle
fusiform
fibres are parallel to muscle
unnipennate
fascicles located on one side of the tendon
bipennate
fascicles arranged ion both side of tendon
control of contraction in SKM
innervated by motor neurones
1 synapse per fibre
AP can only be generated by motor end plates- no gap junctions
propioception
very quick neural feedback loops
signals from muscle spindles (gamma motor neurones)- info on length change
golgi tendon organs (info on strength of muscle contraction)
allows precise control of movement
muscle spindle
muscle fibres surrounded by perineurium-like sheath
