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What are the steps of a contraction at the Neuromuscular Junction?

User Leo Moore
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1 Answer

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28 votes

Answer:

All the steps are down below!!

Step-by-step explanation:

Step 1 - Motor neuron sends action potential (nerve impulse) to the muscle

Step 2 - acetylcholine (ACh) release from vesicles on motor neuron

Step 3 - ACh binds to receptors on muscle membrane & activates 2nd action potential, now on muscle

Step 4 - Action potential opens active transport pumps of sarcoplasmic reticulum

Step 5 - Ca+2 floods sarcoplasm, AChE degrades ACh

Step 6 - Ca+2 attaches to troponin of TT complex and changes its shape

Step 7 - This shape change pulls tropomyosin away from myosin-binding sites on actin

Step 8 - ATP attaches to ATP binding site on myosin crossbridge

Step 9 - ATP use on myosin head in presence of Mg+ splits ATP into ADP+P which energizes myosin head (swings forward)

Step 10 - P flies off and myosin head binds to binding site on actin

Step 11 - DP is pushed off + myosin head is de-energized (pulling actin forward) non myosin swivels back to resting state

Step 12 - Repeat 8-11 until the Ca+2 comes off the TT complex

Hope this Helps!!

User LaurentG
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