Topic: Locomotion: movement types, muscle contraction· Human Physiology

Name the ion responsible for unmasking of active sites for myosin for cross-bridge activity during muscle contraction.

1. Magnesium

2. Sodium

3. Potassium

4. Calcium

Doubtly Asked 30 Oct 2026 NEET UG 2016 Phase 2 Practice test neet Save WhatsApp Report

1 answer

Best answer

Answer: 4. Calcium

When a nerve signal reaches the muscle, Ca²⁺ is released from the sarcoplasmic reticulum.

Ca²⁺ binds to troponin on the thin actin filament. This shifts tropomyosin and unmasks the active sites on actin for the myosin heads, so cross-bridges form and the filaments slide. The ion is calcium.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

Was this answer helpful?

Name the ion responsible for unmasking of active sites for myosin for cross-bridge activity during muscle contraction.

1 answer

Your answer