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 Heart3h 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

4. Tissues & Histology

Introduction to Muscle Tissue

Anatomy & Physiology

4. Tissues & Histology

Introduction to Muscle Tissue

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Multiple Choice

What is the primary function of the sarcoplasmic reticulum in skeletal muscle fibers during muscle contraction?

It stores and releases calcium ions needed to trigger muscle contraction.

It transmits electrical impulses along the muscle fiber.

It synthesizes proteins required for muscle growth.

It generates ATP for muscle contraction.

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Verified step by step guidance

Understand the role of the sarcoplasmic reticulum (SR) in skeletal muscle fibers. The SR is a specialized organelle that plays a critical role in muscle contraction by regulating calcium ion (Ca²⁺) levels.

Recall that muscle contraction is initiated by the release of calcium ions. When a muscle fiber is stimulated by an action potential, the SR releases stored calcium ions into the cytoplasm.

Recognize that calcium ions bind to troponin, a regulatory protein on the actin filaments. This binding causes a conformational change that exposes binding sites on actin for myosin, enabling the cross-bridge cycle and muscle contraction.

Note that the SR also reabsorbs calcium ions after contraction, allowing the muscle fiber to relax and reset for the next contraction. This process is facilitated by calcium pumps in the SR membrane.

Eliminate incorrect options: The SR does not transmit electrical impulses (this is the role of the sarcolemma and T-tubules), synthesize proteins (this is the role of ribosomes), or generate ATP (this is the role of mitochondria). The correct function of the SR is storing and releasing calcium ions needed for muscle contraction.