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MDCAT Biology QUESTION #7742
Question 1

What happens to calcium ions when a skeletal muscle recovers (relaxes) after contraction?

  • Released from SR
  • Released from myosin head
  • Pumped into SR✔️
  • Exchanged for sodium
Correct Answer Explanation

During relaxation, Ca²⁺ is actively pumped back into the sarcoplasmic reticulum (SR) via Ca²⁺-ATPase (SERCA), lowering cytosolic Ca²⁺ and allowing tropomyosin to block myosin-binding sites.