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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

The 1st line of defense that the body uses to prevent infection includes?

Physical barriers to infection (skin).

Chemical barriers to infection (saliva & stomach acid).

Cells of the innate immune system.

Fever and inflammation.

A and B.

C and D.

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Verified step by step guidance

Understand the concept of the body's lines of defense against infection. The first line of defense includes physical and chemical barriers that prevent pathogens from entering the body.

Identify physical barriers: The skin acts as a physical barrier, preventing pathogens from entering the body. It is the body's first line of defense.

Identify chemical barriers: Saliva and stomach acid are chemical barriers that help neutralize or destroy pathogens before they can cause harm.

Recognize that cells of the innate immune system and responses like fever and inflammation are part of the second line of defense, which is activated after pathogens bypass the first line.

Conclude that the first line of defense includes both physical and chemical barriers, which corresponds to options A and B in the problem statement.