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The Role of Ca2+ and ATP in Muscle Contraction

    Calcium ions have a dual role in muscle contraction.
  • They bind to troponin to move tropomyosin and expose the myosin binding sites
  • They activate the ATPase activity of the myosin head
    ATP has a dual role in muscle contraction.
  • It provides the energy for the active transport of Calcium ions into the SR
  • The binding of ATP to the myosin head detaches it from the actin filament and the hydrolysis of ATP returns the myosin head to its original position.

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Specification: OCR Biology A (H420), A-level, 5.1.5 Plant and animal responses. Topic: Muscles.

Key terms in this lesson

Hormone
A chemical messenger, secreted directly into the blood by an endocrine gland, that travels to target cells and alters their activity.
Insulin
A hormone secreted by beta cells of the islets of Langerhans in response to high blood glucose concentration that increases the uptake of glucose by cells.
Glucagon
A hormone secreted by alpha cells of the islets of Langerhans in response to low blood glucose concentration that raises blood glucose concentration.
Hepatocyte
A liver cell, responsible for most of the liver's metabolic functions.

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