For the Following Five Events, Which Is the Correct Sequence

question 65

Multiple Choice

For the following five events, which is the correct sequence that describes the excitation and contraction of a skeletal muscle fiber?
1) Tropomyosin shifts, exposing the myosin-binding sites on actin.
2) Calcium is released from the sarcoplasmic reticulum and binds to the troponin complex.
3) An action potential is propagated down the transverse tubules.
4) Cycles of myosin cross-bridge formation and breakdown cause the thin filaments to slide toward the center of the sarcomere.
5) An action potential in a motor neuron causes the axon to release acetylcholine, which triggers an action potential in a muscle fiber.

• A) 1 → 2 → 3 → 4 → 5
• B) 2 → 1 → 3 → 5 → 4
• C) 2 → 3 → 4 → 1 → 5
• D) 5 → 3 → 2 → 1 → 4

---

Definitions:

Health History

A comprehensive record of a person's past and present health conditions, treatments, medications, allergies, and other relevant health information.

Troponin Level

A measurement of the troponin protein levels in the blood, commonly used to diagnose heart attacks or other heart-related issues.

Myocardial Infarction

Commonly known as a heart attack, it occurs when blood flow decreases or stops to a part of the heart, causing damage to the heart muscle.

Cardiovascular Disease

A range of disorders affecting the heart and blood vessels, often characterized by hypertension, coronary artery disease, and heart failure.