View the animation below, then complete the quiz to test your knowledge of the concept.
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1 | An action potential causes calcium ions to diffuse from the ________ into the ________. |
![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | sarcoplasmic reticulum ; sarcolemma |
![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | sarcoplasmic reticulum ; sarcoplasm |
![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | sarcoplasm ; sarcoplasmic reticulum |
![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | sarcoplasm ; sarcolemma |
![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | sarcolemma ; sarcoplasm |
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2 | Which of the following best describes the role of Ca2+ in muscle contraction? |
![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | It binds to tropomyosin, moving troponin, so that myosin heads can bind to actin. |
![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | It binds to tropomyosin, moving troponin, so that actin heads can bind to myosin. |
![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | It binds to troponin, moving tropomyosin, so that myosin heads can bind to actin. |
![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | It binds to troponin, moving tropomyosin, so that actin heads can bind to myosin. |
![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | It binds to actin, moving myosin, so that troponin can bind to tropomyosin. |
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3 | All of the following are filamentous proteins EXCEPT |
![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | actin. |
![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | myosin. |
![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | troponin. |
![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | tropomyosin. |
![](/olcweb/styles/shared/spacer.gif) | E)![](/olcweb/styles/shared/spacer.gif) | troponin and tropomyosin. |
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4 | An action potential causes depolarization of the T tubule membrane. |
![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | True |
![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | False |
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5 | T-tubules are invaginations of the sarcolemma of a muscle cell. |
![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | True |
![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | False |