https://padlet.com/alycla662/3e3y63qkvas5 Events 1-3 en-us 2019-03-08 15:02:25 UTC 2024-05-26 19:54:45 UTC hello@padlet.com alycla662 https://padlet.com/alycla662/3e3y63qkvas5/wish/339328832 The brain sends an action potential down to a neuromuscular junction (gap between axon terminal and motor cell). This causes voltage gated Ca ions to enter the neuron, which stimulates the release of acetylcholine. When ACh binds to ACh receptor sites, voltage gated Na+ ion channels are activated, and Na+ ions are pumped into the cell while K+ ions ions are pumped out. More Na+ is pumped out than K+is pumped in, causing depolarization. This depolarization spreads down the sarcolemma, opening NA+ channels, and causing an action potential down it. Na concentrations stimulate the opening of voltage gated K+ ion channels, allowing K+ to diffuse across the sarcolemma, in an event called repolarization]]> 2019-03-08 15:04:52 UTC https://padlet.com/alycla662/3e3y63qkvas5/wish/339328832 alycla662 https://padlet.com/alycla662/3e3y63qkvas5/wish/339328886 Step 1:  The action potential moves down the sarcolemma and down the T tubules (protrusion of sarcolemma).

 

]]> 2019-03-08 15:04:58 UTC https://padlet.com/alycla662/3e3y63qkvas5/wish/339328886 alycla662 https://padlet.com/alycla662/3e3y63qkvas5/wish/339328933 Step 2: As the action potential moves down the T tubules, the Sarcoplasmic Reticulum releases CA2+, which flows into cytoplasm.]]> 2019-03-08 15:05:03 UTC https://padlet.com/alycla662/3e3y63qkvas5/wish/339328933 alycla662 https://padlet.com/alycla662/3e3y63qkvas5/wish/339329092 Step 3 and 4: The CA2+ combines with troponin and changes the shape of the actin, removing the blocking actin of the tropomyosin. This exposes the binding site of the myosin. Myosin binds with the actin, forming a cross bridge, and starting muscle contraction.]]> 2019-03-08 15:05:19 UTC https://padlet.com/alycla662/3e3y63qkvas5/wish/339329092 alycla662 https://padlet.com/alycla662/3e3y63qkvas5/wish/339329177 step 1: Myosin, now energized, attaches to an actin myofilament, forming a cross bridge.

]]> 2019-03-08 15:05:27 UTC https://padlet.com/alycla662/3e3y63qkvas5/wish/339329177 alycla662 https://padlet.com/alycla662/3e3y63qkvas5/wish/339329386 Step 3: Myosin attaches to ATP, and this causes the link between myosin and actin to weaken, causing the myosin head to detach and the cross bridge to break]]> 2019-03-08 15:05:49 UTC https://padlet.com/alycla662/3e3y63qkvas5/wish/339329386 alycla662 https://padlet.com/alycla662/3e3y63qkvas5/wish/339329519 Step 4: ATP is hydrolyzed to ADP and P, and the myosin head returns to its high energy "cocked" position.]]> 2019-03-08 15:06:01 UTC https://padlet.com/alycla662/3e3y63qkvas5/wish/339329519 alycla662 https://padlet.com/alycla662/3e3y63qkvas5/wish/339330391 step 2: ADP and P are released, and the myosin head is changed to its bent low-energy state when it pivots and bends.]]> 2019-03-08 15:07:26 UTC https://padlet.com/alycla662/3e3y63qkvas5/wish/339330391