stimulating contraction in striated muscles

contraction

occurs when impulse from a motor neurone via neuromuscular junctions is received

initiation

impulse arrives at presynaptic membrane and action potential causes ACh to fuse with the presynaptic membrane

exocytosis

vesicles secrete ACh which diffuses across the neuromuscular junction and binds to the receptor proteins on the sarcolemma

ion channels

sodium ions diffuse in causing depolarisation of the sarcolemma generating an action potential down the T tubules towards the centre

action potentials

cause calcium voltage gated channels to open and calcium ione diffuse out the SR into the sarcoplasm

troponin

calcium binds to troponin molecules forcing them to change shape

troponin and tropomyosin

change position on the actin filaments…myosin binding sites are exposed on the actin filaments