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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

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

Examples of 1st line defenses to infection which are components of the innate immune system include all of the following except?

Unbroken skin.

Phagocytosis of a pathogen by an immune cell.

Digestive enzymes in saliva.

Destructive acids in gastric juices.

Naturally occurring human microbiome.

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Verified step by step guidance

Understand the concept of the innate immune system, which provides the first line of defense against pathogens. It includes physical barriers, chemical barriers, and biological components.

Identify the physical barriers: Unbroken skin acts as a physical barrier preventing pathogens from entering the body.

Recognize the chemical barriers: Digestive enzymes in saliva and destructive acids in gastric juices help neutralize and destroy pathogens.

Consider the biological components: The naturally occurring human microbiome competes with pathogens and prevents their growth.

Phagocytosis is a process where immune cells engulf and destroy pathogens, which is part of the second line of defense, not the first line. Therefore, it is the exception in this list.