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 Organ Systems

Anatomy & Physiology

1. Introduction to Anatomy & Physiology

Introduction to Organ Systems

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Multiple Choice

Why are the layers of cells (epithelium) thicker in the esophagus compared to areas further down the GI tract?

To enhance secretion of digestive enzymes

To facilitate the production of mucus

To increase nutrient absorption

To protect against abrasion from swallowed food

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Verified step by step guidance

Understand the function of the esophagus: The esophagus is primarily responsible for transporting food from the mouth to the stomach. Unlike other parts of the GI tract, it does not play a significant role in digestion or absorption.

Recognize the type of epithelium in the esophagus: The esophagus is lined with stratified squamous epithelium, which consists of multiple layers of cells. This type of epithelium is designed to protect against mechanical stress and abrasion.

Compare the esophagus to other parts of the GI tract: Areas further down the GI tract, such as the stomach and intestines, are lined with simple columnar epithelium. This thinner epithelium facilitates secretion, absorption, and mucus production, which are essential for digestion.

Relate the thicker epithelium to its protective role: The esophagus encounters rough and abrasive materials, such as chewed food, which can damage the lining. The thicker, stratified epithelium provides a durable barrier to protect against this mechanical damage.

Conclude why the correct answer is 'To protect against abrasion from swallowed food': The esophagus does not require thick layers for secretion, mucus production, or nutrient absorption. Its primary need is protection from physical abrasion caused by food passing through.