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

21. The Immune System

Physical Barriers in First-Line Defenses: Skin

Anatomy & Physiology

21. The Immune System

Physical Barriers in First-Line Defenses: Skin

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Multiple Choice

Does the skin provide a diffusion barrier to all gases?

No, the skin allows only toxic gases to diffuse through.

No, the skin allows some gases like oxygen and carbon dioxide to diffuse through.

Yes, but only when the skin is dry.

Yes, the skin completely blocks all gases from diffusing through.

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Verified step by step guidance

Understand the structure of the skin: The skin is composed of multiple layers, including the epidermis, dermis, and subcutaneous tissue. The outermost layer, the epidermis, acts as a barrier to many substances.

Consider the properties of gases: Gases like oxygen and carbon dioxide are small and nonpolar, which allows them to diffuse through certain barriers more easily than larger or polar molecules.

Evaluate the permeability of the skin: While the skin is a barrier to many substances, it is not completely impermeable. Some gases can diffuse through the skin, particularly those that are small and nonpolar.

Recognize the physiological role of gas exchange: The skin does allow for some gas exchange, although it is not the primary site for this process. The lungs are the main organs responsible for gas exchange in the body.

Conclude with the correct understanding: The skin does not completely block all gases. It allows some gases, like oxygen and carbon dioxide, to diffuse through, although this is limited compared to the respiratory system.