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 First-Line Defenses

Anatomy & Physiology

21. The Immune System

Introduction to First-Line Defenses

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Multiple Choice

How does lysozyme on the skin and in tears protect against bacterial pathogens?

By inhibiting bacterial DNA replication

By neutralizing bacterial toxins

By disrupting bacterial protein synthesis

By breaking down the peptidoglycan in bacterial cell walls

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Verified step by step guidance

Understand the role of lysozyme: Lysozyme is an enzyme that is part of the innate immune system, found in various body fluids such as tears and saliva, as well as on the skin.

Identify the target of lysozyme: Lysozyme specifically targets the peptidoglycan layer in bacterial cell walls, which is a crucial structural component for bacteria, especially Gram-positive bacteria.

Explore the mechanism of action: Lysozyme breaks down the peptidoglycan by cleaving the bonds between N-acetylmuramic acid and N-acetylglucosamine, which are the sugar components of the peptidoglycan.

Consider the effect on bacteria: By breaking down the peptidoglycan, lysozyme compromises the integrity of the bacterial cell wall, leading to cell lysis and death of the bacteria.

Relate to the immune defense: This action helps protect the body from bacterial infections by reducing the number of viable bacterial pathogens on the skin and in tears.