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Action Potentials in Cardiac Muscle Cells

View the animation below, then complete the quiz to test your knowledge of the concept.






1In a cardiac muscle cell, the membrane potential increases rapidly...
A)when potassium gates open and potassium diffuses into the cardiac muscle fiber.
B)when potassium gates open and potassium diffuses out of the cardiac muscle fiber.
C)when the sodium gates open and sodium diffuses into the cardiac muscle fiber.
D)when the sodium gates open and sodium diffuses out of the cardiac muscle fiber.
E)when calcium gates open and calcium diffuses into the cardiac muscle fiber.



2In a cardiac muscle cell, the membrane potential begins to decrease...
A)when potassium gates open and potassium diffuses into the cardiac muscle fiber.
B)when potassium gates open and potassium diffuses out of the cardiac muscle fiber.
C)when the sodium gates open and sodium diffuses into the cardiac muscle fiber.
D)when the sodium gates open and sodium diffuses out of the cardiac muscle fiber.
E)when calcium gates open and calcium diffuses into the cardiac muscle fiber.



3In a cardiac muscle cell, the membrane potential decreases rapidly...
A)when potassium gates open and potassium diffuses into the cardiac muscle fiber.
B)when potassium gates open and potassium diffuses out of the cardiac muscle fiber.
C)when the sodium gates open and sodium diffuses into the cardiac muscle fiber.
D)when the sodium gates open and sodium diffuses out of the cardiac muscle fiber.
E)when calcium gates open and calcium diffuses into the cardiac muscle fiber.



4An action potential in a cardiac muscle fiber is identical to an action potential in a skeletal muscle fiber.
A)True
B)False



5During an action potential, the cardiac muscle cell membrane is most permeable to sodium.
A)True
B)False







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