where are the calcium ions stored in a muscle fibre? how do the calcium ions affect the process of muscle co traction?
Calcium ions are stored in the endoplasmic reticulum of the muscle fiber.
Calcium ions bind to the calcium binding site of the troponin molecule on actin filament exposing the active site for myosin head on actin filament.
This enables Myosin heads to bind with actin and slide actin over the length to bring about contraction.