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Muscle Contraction. 1.Acetylcholine (Ach) is released from the axon terminal (nerve) into the synaptic cleft and binds to Ach receptors in the sarcolemma.

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Presentation on theme: "Muscle Contraction. 1.Acetylcholine (Ach) is released from the axon terminal (nerve) into the synaptic cleft and binds to Ach receptors in the sarcolemma."— Presentation transcript:

1 Muscle Contraction

2 1.Acetylcholine (Ach) is released from the axon terminal (nerve) into the synaptic cleft and binds to Ach receptors in the sarcolemma (muscle cell)

3 2. Action potential is generated and muscle fiber becomes excited 3. Calcium (Ca 2+ ) is released from the sarcoplasmic reticulum 4. Ca 2+ binds to troponin, causing tropomyosin on actin to shift and myosin binding sites become exposed.

4 5. ATP binds to myosin head, causing it to be in the “cocked” position. 6. Actin and myosin bind, forming a cross-bridge

5

6 7. Myosin head flexes, causing actin to be pulled along the myosin, shortening the sarcomere (remember, muscles only pull/shorten/contract)

7

8 Muscle Relaxation

9 Another ATP molecule releases myosin head from actin. Ca2+ is transported back to the sarcoplasmic reticulum, causing tropomyosin to re-cover the myosin binding site Sarcomere “slides back” to its original position.


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