https://padlet.com/jeskok696/hzakedjhj0xx Steps of Muscle Contraction en-us 2018-01-12 15:03:09 UTC 2025-10-23 14:46:44 UTC hello@padlet.com jeskok696 https://padlet.com/jeskok696/hzakedjhj0xx/wish/222072610 The brain sends action potential through the motor unit down to a neuromuscular junction. Action potential causes voltage gated calcium ion channels to enter the neuron. ACh is released into the cleft. ACh binds to a receptor and activates ion channels which pumps Na and K, which causes the cell to become less negative, or depolarized. This depolarization causes sodium channels to open which initiates action potential that moves along the length of the sarcolemma. Na concentrations open K pumps so that potassium can pump across the membrane and out of the muscle fiber, known as repolarization.

]]> 2018-01-17 14:29:58 UTC https://padlet.com/jeskok696/hzakedjhj0xx/wish/222072610 jeskok696 https://padlet.com/jeskok696/hzakedjhj0xx/wish/222072675 Step 1:  The action potential moves down the sarcolemma and down the T-tubules. ]]> 2018-01-17 14:30:07 UTC https://padlet.com/jeskok696/hzakedjhj0xx/wish/222072675 jeskok696 https://padlet.com/jeskok696/hzakedjhj0xx/wish/222072917 Step 2: Transmission of the action potential along the T-tubules cause the adjacent sarcoplasmic reticulum (SR) to release Ca2+ which flows into the muscle cell.]]> 2018-01-17 14:30:43 UTC https://padlet.com/jeskok696/hzakedjhj0xx/wish/222072917 jeskok696 https://padlet.com/jeskok696/hzakedjhj0xx/wish/222073081 Step 3 and 4: Ca2+ combines with troponin and removes the blocking action of tropomyosin by changing the shape of the actin so that the myosin binding sites are exposed. Myosin binding to actin forms cross bridges and contraction begins. ]]> 2018-01-17 14:31:07 UTC https://padlet.com/jeskok696/hzakedjhj0xx/wish/222073081 jeskok696 https://padlet.com/jeskok696/hzakedjhj0xx/wish/222073326 step 1: Cross bridge formation: high energy myosin head attaches to actin myofilaments forming a cross bridge.]]> 2018-01-17 14:31:41 UTC https://padlet.com/jeskok696/hzakedjhj0xx/wish/222073326 jeskok696 https://padlet.com/jeskok696/hzakedjhj0xx/wish/222073341 step 2: Power stroke: myosin head pivots and pulls actin filament toward the M line.]]> 2018-01-17 14:31:45 UTC https://padlet.com/jeskok696/hzakedjhj0xx/wish/222073341 jeskok696 https://padlet.com/jeskok696/hzakedjhj0xx/wish/222073362 Step 4: Cocking of myosin head: energy from hydrolysis of ATP "reactivates" myosin head into its cocked state.]]> 2018-01-17 14:31:49 UTC https://padlet.com/jeskok696/hzakedjhj0xx/wish/222073362 jeskok696 https://padlet.com/jeskok696/hzakedjhj0xx/wish/222073846 Step 3: Cross bridge detachment:  ATP attaches to the myosin head, causing cross bridges to detach.]]> 2018-01-17 14:32:58 UTC https://padlet.com/jeskok696/hzakedjhj0xx/wish/222073846