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

23. The Digestive System

Introduction to the Digestive System

Anatomy & Physiology

23. The Digestive System

Introduction to the Digestive System

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Multiple Choice

Which of the following correctly lists the layers of the digestive tract wall from innermost to outermost?

Serosa, muscularis externa, submucosa, mucosa

Submucosa, mucosa, muscularis externa, serosa

Mucosa, submucosa, muscularis externa, serosa

Mucosa, muscularis externa, submucosa, serosa

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Verified step by step guidance

Step 1: Begin by understanding the structure of the digestive tract wall. The wall is composed of four main layers, each with distinct functions and characteristics. These layers are organized from the innermost (closest to the lumen) to the outermost (facing the external environment).

Step 2: Identify the innermost layer, the mucosa. The mucosa is responsible for secretion, absorption, and protection. It consists of three sublayers: the epithelium, lamina propria, and muscularis mucosae.

Step 3: Next, recognize the submucosa, which lies just outside the mucosa. The submucosa contains connective tissue, blood vessels, lymphatics, and nerves, providing support and nourishment to the mucosa.

Step 4: The third layer is the muscularis externa. This layer is responsible for peristalsis and segmentation, facilitating the movement of food through the digestive tract. It typically consists of two layers of smooth muscle: an inner circular layer and an outer longitudinal layer.

Step 5: Finally, identify the outermost layer, the serosa. The serosa is a protective layer composed of connective tissue and a simple squamous epithelium. In regions where the digestive tract is not covered by serosa, it is instead covered by adventitia, which is a connective tissue layer.