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

Introduction to Innate Immunity

Anatomy & Physiology

21. The Immune System

Introduction to Innate Immunity

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Multiple Choice

Which of the following is considered a first line of defense in innate immunity?

Inflammation

Natural killer cells

Intact skin

Fever

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Verified step by step guidance

Understand the concept of innate immunity: Innate immunity is the body's first line of defense against pathogens. It is non-specific and includes physical, chemical, and cellular defenses that act immediately or within hours of an infection.

Identify the components of the first line of defense: The first line of defense includes physical barriers (e.g., intact skin and mucous membranes), chemical barriers (e.g., enzymes in saliva, stomach acid, and antimicrobial peptides), and mechanical processes (e.g., cilia movement and flushing actions like tears and urine).

Recognize the role of intact skin: Intact skin acts as a physical barrier preventing pathogens from entering the body. It is covered by keratinized cells and has antimicrobial properties due to secretions like sweat and sebum, which create an acidic environment hostile to microbes.

Differentiate between first and second lines of defense: Inflammation, fever, and natural killer cells are part of the second line of defense in innate immunity. These mechanisms are activated after pathogens bypass the first line of defense and enter the body.

Conclude that intact skin is the correct answer: Based on the definition and components of the first line of defense, intact skin is considered a primary physical barrier in innate immunity.