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

After the age of 30, the number of ______ in existing muscle fibers decreases.

myofibrils

nuclei

sarcomeres

mitochondria

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Verified step by step guidance

Step 1: Understand the structure of muscle fibers. Muscle fibers are composed of several key components, including myofibrils, nuclei, sarcomeres, and mitochondria, each playing a distinct role in muscle function.

Step 2: Recall the physiological changes that occur in muscle fibers with aging. After the age of 30, muscle fibers experience a decline in their ability to maintain certain structures due to reduced protein synthesis and cellular repair mechanisms.

Step 3: Analyze the function of each option provided: Myofibrils are responsible for muscle contraction, nuclei regulate cellular activity, sarcomeres are the functional units of myofibrils, and mitochondria produce energy for muscle function.

Step 4: Consider which component is most likely to decrease in number due to aging. Aging leads to a reduction in the contractile machinery of muscle fibers, which directly impacts the number of myofibrils.

Step 5: Conclude that the correct answer is 'myofibrils,' as they are the structural components of muscle fibers that decrease in number with age, leading to reduced muscle strength and function.