Question

click and drag on elements in order. place the following steps of excitation - contraction coupling in order, starting at the top. instructions. calcium binds to troponin. calcium is released from the sarcoplasmic reticulum. troponin changes shape and alters the position of tropomyosin. binding sites on actin filaments are exposed. myosin heads bind to actin.

Explanation:

In excitation - contraction coupling, calcium is first released from the sarcoplasmic reticulum. It then binds to troponin. This binding causes troponin to change shape and alter tropomyosin's position. As a result, the binding sites on actin filaments are exposed, allowing myosin heads to bind to actin.

Answer:

1. Calcium is released from the sarcoplasmic reticulum.
2. Calcium binds to troponin.
3. Troponin changes shape and alters the position of tropomyosin.
4. Binding sites on actin filaments are exposed.
5. Myosin heads bind to actin.