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

1. Introduction to Anatomy & Physiology

Introduction to Directional Terms

Anatomy & Physiology

1. Introduction to Anatomy & Physiology

Introduction to Directional Terms

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Multiple Choice

Which of the following layers of the GI tract contains skeletal muscle?

Submucosa

Muscularis externa of the upper esophagus

Mucosa

Serosa

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Verified step by step guidance

Understand the structure of the gastrointestinal (GI) tract, which consists of four main layers: mucosa, submucosa, muscularis externa, and serosa.

Recognize that the muscularis externa is primarily composed of smooth muscle throughout most of the GI tract, but in specific regions, such as the upper esophagus, it contains skeletal muscle.

Recall that skeletal muscle is under voluntary control, which is necessary for the initial stages of swallowing in the upper esophagus.

Eliminate the other options: the mucosa is the innermost layer responsible for secretion and absorption, the submucosa contains connective tissue, blood vessels, and nerves, and the serosa is the outermost protective layer.

Conclude that the correct answer is the muscularis externa of the upper esophagus, as it is the only layer in the GI tract that contains skeletal muscle in this specific region.