https://padlet.com/marham934/k03ezbk1q2em Made with panache en-us 2019-03-08 13:17:56 UTC 2026-01-03 15:52:35 UTC hello@padlet.com marham934 https://padlet.com/marham934/k03ezbk1q2em/wish/339277423 The brain sends an action potential through the motor unit down the Neuromuscular junction. The action potential then causes voltage gated calcium ion channels to open, allowing calcium ions to enter the neuron. The increase of calcium stimulates the release of acetylcholine, which is released into the cleft. The ACh binds to the ACh receptor sight and activates voltage gated sodium channels which pumps Na+ in and K+ out, causing the cell inferior to become depolarized. Initial depolarization spreads to adjacent areas, opening voltage gated sodium channels and initiating an action potential that moves along the lengths of the sarcolemma. Na+ concentrations caused by depolarization stimulate a change in the membrane permeability by opening voltage gated K+ pumps, which allow K+ to diffuse across the sarcolemma out of the muscle fiber, repolarizing the cell. ]]> 2019-03-08 13:23:21 UTC https://padlet.com/marham934/k03ezbk1q2em/wish/339277423 marham934 https://padlet.com/marham934/k03ezbk1q2em/wish/339277493 Step 1:  The action potential moves down the sarcolemma (muscle cell membrane) and down the T tubules (protrusion of the sarcolemma that protrudes deep into the muscle cell).  

 

]]> 2019-03-08 13:23:33 UTC https://padlet.com/marham934/k03ezbk1q2em/wish/339277493 marham934 https://padlet.com/marham934/k03ezbk1q2em/wish/339277533 Step 2: Transmission of the action potential along the T tubules cause the adjacent sarcoplasmic reticulum to release Ca2+ which flows into the cytosol. ]]> 2019-03-08 13:23:39 UTC https://padlet.com/marham934/k03ezbk1q2em/wish/339277533 marham934 https://padlet.com/marham934/k03ezbk1q2em/wish/339277604 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 actin so that the myosin binding site is exposed. The myosin then binds to the acton, forming a cross bridge and contraction begins.

]]> 2019-03-08 13:23:48 UTC https://padlet.com/marham934/k03ezbk1q2em/wish/339277604 marham934 https://padlet.com/marham934/k03ezbk1q2em/wish/339277643 Step 1: Cross bridge formation: high - energy myosin head attaches to actin myofilaments forming a cross bridge. 

]]> 2019-03-08 13:23:53 UTC https://padlet.com/marham934/k03ezbk1q2em/wish/339277643 marham934 https://padlet.com/marham934/k03ezbk1q2em/wish/339277701 Step 2: Working (power) stroke: myosin head pivots and pulls on the actin filaments, pulling it toward M line.]]> 2019-03-08 13:24:02 UTC https://padlet.com/marham934/k03ezbk1q2em/wish/339277701 marham934 https://padlet.com/marham934/k03ezbk1q2em/wish/339277728 Step 3: Cross bridge detachment: ATP attaches to myosin head, causing cross bridge to detach.]]> 2019-03-08 13:24:06 UTC https://padlet.com/marham934/k03ezbk1q2em/wish/339277728 marham934 https://padlet.com/marham934/k03ezbk1q2em/wish/339277749 Step 4: Cocking of myosin head: as ATP is split into ADP and P, energy from hydrolysis of ATP "cocks" myosin head into high-energy state. ]]> 2019-03-08 13:24:11 UTC https://padlet.com/marham934/k03ezbk1q2em/wish/339277749