Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart2h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

9. Muscle Tissue

Steps of Muscle Contraction

Anatomy & Physiology

9. Muscle Tissue

Steps of Muscle Contraction

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Multiple Choice

When an action potential arrives at the neuromuscular junction, the most immediate result is __________.

the release of acetylcholine from the motor neuron

the depolarization of the sarcolemma

a rise in intracellular Ca²⁺ levels in the muscle fiber

the formation of actin-myosin cross bridges

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Verified step by step guidance

Understand the sequence of events at the neuromuscular junction: An action potential travels down the motor neuron to the axon terminal.

Recognize that the arrival of the action potential at the axon terminal causes voltage-gated calcium channels to open, allowing Ca²⁺ ions to enter the neuron.

Identify that the influx of Ca²⁺ ions into the neuron triggers synaptic vesicles to release acetylcholine (ACh) into the synaptic cleft.

Note that acetylcholine diffuses across the synaptic cleft and binds to receptors on the sarcolemma (muscle cell membrane), leading to depolarization.

Understand that the depolarization of the sarcolemma eventually leads to a rise in intracellular Ca²⁺ levels and the formation of actin-myosin cross bridges, but these are subsequent steps following the release of acetylcholine.