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 Heart2h 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: Mucous Membrane

Anatomy & Physiology

21. The Immune System

Physical Barriers in First-Line Defenses: Mucous Membrane

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Multiple Choice

Which of the following is/are NOT a surface barrier to pathogen influx?

complement cascade

mucous membranes

skin secretions

saliva and tears

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Verified step by step guidance

Understand the concept of surface barriers: Surface barriers are the first line of defense in the immune system, preventing pathogens from entering the body. They include physical and chemical barriers such as skin, mucous membranes, and secretions.

Identify the options given: The options provided are complement cascade, mucous membranes, skin secretions, and saliva and tears.

Evaluate each option: Determine which of these options function as surface barriers. Mucous membranes, skin secretions, and saliva and tears are all physical or chemical barriers that prevent pathogen entry.

Understand the role of complement cascade: The complement cascade is part of the immune system but functions as a series of proteins that enhance the ability of antibodies and phagocytic cells to clear pathogens, rather than acting as a surface barrier.

Conclude which option is not a surface barrier: Based on the evaluation, identify that the complement cascade is not a surface barrier to pathogen influx.