Caffeine Aids in the Movement of Calcium Ions Across Membranes

question 52

Multiple Choice

Caffeine aids in the movement of calcium ions across membranes by both making it easier for the Ca⁺⁺ channels to open and by holding the channels open longer. How would the administration of caffeine to a muscle fiber affect its contraction?

• A) Caffeine would increase the strength of the fiber's contraction.
• B) Caffeine would allow more cross bridges to form in the fiber.
• C) Caffeine would increase the duration of the fiber's contraction.
• D) At high enough levels, caffeine would cause the muscle fiber to contract without a signal from the associated motor neuron.
• E) Caffeine would have all of these effects.

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