In: Anatomy and Physiology
PUT THE EVENTS OF MUSCLE CONTRACTION IN ORDER
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Calcium ions attach to the
troponin. This causes the tropomyosin to move away from the actin
active sites.
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An ATP molecule provides
the energy to return the myosin cross bridge back to its original
(cocked) position
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Myosin heads bend and pull
the actin over the myosin
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Myosin cross bridges attach
to the active sites of the actin
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Nerve stimulation causes
Calcium ions to be released from the Sarcoplasmic Reticulum
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1. Nerve stimulation causes Calcium ions to be released from the Sarcoplasmic Reticulum 2.Calcium ions attach to the troponin. This causes the tropomyosin to move away from the actin active sites 3. Myosin cross bridges attach to the active sites of the actin 4. Myosin heads bend and pull the actin over the myosin 5. An ATP molecule provides the energy to return the myosin cross bridge back to its original (cocked) position
Explanation: Action potential reaches sarcoplasmic reticulum through T tubules and stimulates sarcoplasmic reticulum to release calcium. This calcium binds to troponin which moves tropomysin from active site of actin. Then myosin head attaches to actin to form cross bridge. During power stroke myosin head bends which pulls the actin over myosin and causes muscle contraction. After this new molecule of ATP gets attached to myosin and breaks cross bridge and ATP gets hydrolysed to ADP and inorganic phosphate which makes the myosin return to cocked position.