https://padlet.com/brimad674/8ixyga7v68v the three events of muscle contraction en-us 2019-03-08 14:09:43 UTC 2025-10-10 16:18:58 UTC hello@padlet.com brimad674 https://padlet.com/brimad674/8ixyga7v68v/wish/339301363 the brain sends a nerve impulse (action potential) through the motor unit to a neuromuscular junction. the action potential cause voltage gated Ca+ channels to open allowing Ca+ to enter. this stimulates the release of Ach which releases into the cleft. Ach binds to Ach receptors and activates voltage gated Na+ channels which pump Na+ in and K+ out causing the cell interior to be depolarized. This depolarization spreads, opening more Na+ channels for the action potential to travel down the sarcolemma. Na+ concentrations from this cause change in membrane permeability, opening K+ channels to allow K+ to enter and diffuse across membrane (repolarization). ]]> 2019-03-08 14:13:48 UTC https://padlet.com/brimad674/8ixyga7v68v/wish/339301363 brimad674 https://padlet.com/brimad674/8ixyga7v68v/wish/339301422 step one : the action potential moves down the sarcolemma and down the t tubules. 
 

]]> 2019-03-08 14:13:53 UTC https://padlet.com/brimad674/8ixyga7v68v/wish/339301422 brimad674 https://padlet.com/brimad674/8ixyga7v68v/wish/339301470 step two : the transmission of action potential along the t tubules causes adjacent sarcoplasmic reticulum to release Ca2+ which flows into the cytoplas]]> 2019-03-08 14:14:00 UTC https://padlet.com/brimad674/8ixyga7v68v/wish/339301470 brimad674 https://padlet.com/brimad674/8ixyga7v68v/wish/339301522 step three : Ca2+ combines with troponin and removes the blocking action of the tropomyosin by changing the shape of the actin so the myosin binding sites are exposed. ]]> 2019-03-08 14:14:06 UTC https://padlet.com/brimad674/8ixyga7v68v/wish/339301522 brimad674 https://padlet.com/brimad674/8ixyga7v68v/wish/339301773 step one : the cross bridge formation where the myosin head attaches to the actin myofilament.]]> 2019-03-08 14:14:35 UTC https://padlet.com/brimad674/8ixyga7v68v/wish/339301773 brimad674 https://padlet.com/brimad674/8ixyga7v68v/wish/339301818 step two : the working stroke where ADP and p1 are released and the myosin head pivots and bends (now in low energy position), pulling the actin filament towards the m line.]]> 2019-03-08 14:14:41 UTC https://padlet.com/brimad674/8ixyga7v68v/wish/339301818 brimad674 https://padlet.com/brimad674/8ixyga7v68v/wish/339301865 step three : the cross bridge detachment after the ATP attaches to the myosin, the link now weakens and detaches.]]> 2019-03-08 14:14:47 UTC https://padlet.com/brimad674/8ixyga7v68v/wish/339301865 brimad674 https://padlet.com/brimad674/8ixyga7v68v/wish/339301939 step four : the cocking of the myosin head where ATP is hydrolyzed to ADP and p1 and the myosin head returns to its high energy position]]> 2019-03-08 14:14:55 UTC https://padlet.com/brimad674/8ixyga7v68v/wish/339301939