Question

Sort the 8 events, into a sequence that corresponds to the correct events:

- Myosin filaments continue to slide actin toward the M-line.
- Sodium ions enter the cell, initiating an action potential.
- Calcium binds to troponin, causing tropomyosin to move.
- Myosin binds to actin.
- Calcium ions are released from the sarcoplasmic reticulum.
- Acetylcholine binds ligand- gated sodium channels.
- Myosin cross- bridges alternately swing and detach using ATP energy
- An action potential travels down the sarcolemma and T tubules.

Answer 1

The correct sequence for a muscle fiber to contract starts with acetylcholine binding to sodium channels and ends with myosin filaments sliding actin towards the M-line, following several steps involving action potentials and calcium ions.

Step-by-step explanation:

Sorting the events into the correct sequence for muscle fiber contraction involves understanding the interaction of cellular structures and biochemical signals. Here's the ordered sequence:

1. Acetylcholine binds ligand-gated sodium channels.
2. Sodium ions enter the cell, initiating an action potential.
3. An action potential travels down the sarcolemma and T tubules.
4. Calcium ions are released from the sarcoplasmic reticulum.
5. Calcium binds to troponin, causing tropomyosin to move.
6. Myosin binds to actin.
7. Myosin cross-bridges alternately swing and detach using ATP energy.
8. Myosin filaments continue to slide actin toward the M-line.

These steps correspond to the excitation-contraction coupling process where a nerve impulse leads to muscle contraction. The interplay between acetylcholine, action potentials, calcium ions, and structural proteins of the sarcomere is crucial for this process.