Respuesta :
Answer;
3, 6, 1, 2, 5, 7, 4
That is;
- Acetylcholine binds to receptors on the motor end plate
- Chemically regulated ion channels open, causing depolarization
- End plate potentials trigger action potentials
- Transverse tubules convey potentials into the interior of the cell
- Ca2+ is released from the sarcoplasmic reticulum
- Ca2+ ions bind to troponin-C, pulling on tropomyosin
- Binding sites on actin are uncovered, allowing myosin to bind and carry out power strokes
Explanation;
- The sequence of events leading to contraction is initiated somewhere in the central nervous system.
- At the motor end plate, an action potential causes the release of packets or quanta of acetylcholine into the synaptic clefts on the surface of the muscle fiber.
- Acetylcholine causes the electrical resting potential under the motor end plate to change, and this then initiates an action potential which passes in both directions along the surface of the muscle fiber.
- At the opening of each transverse tubule onto the muscle fiber surface, the action potential spreads inside the muscle fiber.
- At each point where a transverse tubule touches part of the sarcoplasmic reticulum, it causes the sarcoplasmic reticulum to release Ca++ ions.
- The calcium ions result in movement of troponin and tropomyosin on their thin filaments,allowing myosin to strongly bind and perform a power stoke
