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.

Question

Quizplus · Accepted Answer

The movement of calcium ions across membranes is necessary for muscle contraction, and caffeine aids in this process by making it easier for channels to open and holding them open longer. This allows for more calcium ions to enter the muscle fiber, leading to more cross bridges forming and a stronger contraction. Additionally, the longer duration of the calcium influx could lead to a longer contraction. At high enough levels, caffeine could also cause the muscle fiber to contract without a signal from the associated motor neuron. Therefore, caffeine would have all of these effects on muscle contraction.

Caffeine Aids in the Movement of Calcium Ions Across Membranes