structure and regulation of skeletal muscle Flashcards
what is A band?
band that is anisotropic to light
what is the I band?
band that is isotropic to light
what is a sarcomere?
minimum functional unit of striated muscle, spans between Z lines
where are thick myosin filaments localised to?
A band
what is the M band?
location of attachment between myosin filaments
on what does the thickness of the I band depend on?
how stretched the muscle is
what happens to the thickness of the I band when the muscle is: contracting and stretched?
stretched: I band gets wider
contracting: I band gets thinner as it is pulled into the A band
what are the components of myofilaments?
myosin heavy chain x2
globular heads
a-helical hinge and tail region
regulatory light chain and alkali light chain present on the head of myosin heavy chain
what is the role of regulatory light chain?
modulates enzyme activity
where does calcium bind to the thin filament?
tropomyosin/troponin complex
what is the role of titin?
stabilises myofilament position
what does the tension developed by titin depend on?
cytoplasmic calcium levels - increased tension in exercise
what is the end plate?
branching at synaptic terminals
what is the NT inside synaptic vesicles at the NMJ?
acetylcholine
what is the role of the invaginations to the end plate membrane?
increase surface area
