Neuromuscular Junction - The Real Thing! Botulinum toxin binds to pre-synaptic membranes at neuromuscular junctions, enters the neuron, and then a component of the toxin interferes with the release of neurotransmitter. Release of acetylcholine is blocked. No acetylcholine? No muscular contraction. (flaccid paralysis)
Ca 2+ binds the troponin molecules on the thin actin myofilaments. This leads to the ability of the thick myosin filaments to bind the actin. The myosin heads pull the actin molecules inward, causing the whole fiber to shorten.
A Body Temperature Rigor MortisTime since death WarmNot yet stiffDead not more than 3 hours WarmStiffness starting in head Dead 3 to 8 hours ColdStiffDead 9 to 36 hours ColdNo longer stiffDead more than 36 hours