BRAINCAKERelease of Calcium Ions into the Sarcoplasm
The depolarisation of the sarcolemma is spread throughout the muscle fibre by the T-tubles which are in contact with the sarcoplasmic reticulum (SR). The SR actively absorbs calcium ions from the sarcoplasm.
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Key terms in this lesson
- Depolarisation
- A change in the potential difference across a membrane that makes the inside less negative, caused by an influx of sodium ions.
- Actin
- A thin protein filament in a myofibril that, together with myosin, slides during muscle contraction.
- Myosin
- A thick protein filament in a myofibril with globular heads that bind to actin and pull it during muscle contraction.
- Troponin
- A globular protein complex bound to tropomyosin that binds calcium ions, causing tropomyosin to move and expose the myosin-binding sites on actin.
- Sarcolemma
- The specialised cell surface membrane of a muscle fibre.