https://padlet.com/alywil271/1is72anqjymy Events 1,2, and 3 en-us 2019-03-08 15:02:17 UTC 2026-01-13 18:18:38 UTC hello@padlet.com alywil271 https://padlet.com/alywil271/1is72anqjymy/wish/339328563 The brain sends a nerve impulse through the motor unit down to a neuromuscular junction (axon terminal). The nerve impulse causes voltage gated calcium ion channels to opens which allows calcium ions to enter the neuron. This increase in calcium stimulates the release of acetylcholine which is released into the cleft. Acetylcholine binds to a receptor site and activates voltage gated Na+ ion channel which pumps Na+ ions out and K+ ions in. More Na is pumped out causing the cell interior to become depolarized. The depolarization then spreads to adjacent areas, opening voltage gated Na+ channels and eventually initiating an action potential that moves along the lengths of the sarcolemma. Lastly, Na concentrations caused by depolarization stimulate a change in membrane permeability by opening voltage gated K+ pumps which allows K to diffuse across the sarcolemma out of the muscle fiber, this is repolarization.]]> 2019-03-08 15:04:22 UTC https://padlet.com/alywil271/1is72anqjymy/wish/339328563 alywil271 https://padlet.com/alywil271/1is72anqjymy/wish/339328843 Step 2: Transmission of the action potential along the t-tubules causes the adjacent sarcoplasmic reticulum to release Ca2+, which flows into the cytosol.]]> 2019-03-08 15:04:53 UTC https://padlet.com/alywil271/1is72anqjymy/wish/339328843 alywil271 https://padlet.com/alywil271/1is72anqjymy/wish/339328948 Step 3 and 4: Ca2+ combines with troponin (protein located on actin) and removes the blocking action of tropomyosin by changing the shape of the troponin so that the myosin binding sites are exposed. The myosin then binds to the actin and forms cross bridges and contraction begins.

]]> 2019-03-08 15:05:05 UTC https://padlet.com/alywil271/1is72anqjymy/wish/339328948 alywil271 https://padlet.com/alywil271/1is72anqjymy/wish/339329047 step 1: The myosin cross bridge attaches to the actin myofilament.

]]> 2019-03-08 15:05:15 UTC https://padlet.com/alywil271/1is72anqjymy/wish/339329047 alywil271 https://padlet.com/alywil271/1is72anqjymy/wish/339329121 step 2: The working stroke - Myosin head pivots and bends as it pulls on the actin filament, sliding it toward the M]]> 2019-03-08 15:05:22 UTC https://padlet.com/alywil271/1is72anqjymy/wish/339329121 alywil271 https://padlet.com/alywil271/1is72anqjymy/wish/339329186 Step 4: New ATP is split into ADP and P, cocking of myosin head occurs. ]]> 2019-03-08 15:05:28 UTC https://padlet.com/alywil271/1is72anqjymy/wish/339329186 alywil271 https://padlet.com/alywil271/1is72anqjymy/wish/339329824 Step 1:  The action potential moves down the sarcolemma and down the t-tubules. 

 

]]> 2019-03-08 15:06:29 UTC https://padlet.com/alywil271/1is72anqjymy/wish/339329824 alywil271 https://padlet.com/alywil271/1is72anqjymy/wish/339331046 Step 3: New ATP attaches to myosin head and cross bridge detaches. ]]> 2019-03-08 15:08:38 UTC https://padlet.com/alywil271/1is72anqjymy/wish/339331046