Which phase of a contraction is calcium actively transported back to the sarcoplasmic reticulum?

Question

Quizplus · Accepted Answer

During the latent phase: The nerve impulse comes down the neuron; Acetylcholine is released and fits into the receptors on the muscle cell; The sarcoplasmic reticulum releases calcium; The calcium binds to troponin; tropomyosin shifts position to expose the active sites; and Myosin grabs hold of actin. The muscle cell has not shortened during this phase. During the contraction phase: Myosin pulls (power stroke). The muscle cell shortens. During the relaxation phase: myosin lets go. The muscle goes back to shape because it is elastic (elasticity). During the refractory phase: The calcium is actively transported back to the sarcoplasmic reticulum and the muscle produces acetylcholinesterase to remove the acetylcholine from the receptors. The muscle still appears to be relaxed.

Which Phase of a Contraction Is Calcium Actively Transported Back