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

First-Line Defenses: Chemical Barriers

Anatomy & Physiology

21. The Immune System

First-Line Defenses: Chemical Barriers

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Multiple Choice

Which cells do NOT have a direct role in phagocytosis?

neutrophils

macrophages

dendritic cells

NK cells

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Verified step by step guidance

Understand the concept of phagocytosis: Phagocytosis is a process by which certain cells, known as phagocytes, engulf and digest cellular debris, foreign substances, microbes, and other particles.

Identify the cells involved in phagocytosis: Neutrophils, macrophages, and dendritic cells are all types of phagocytes that play a direct role in phagocytosis.

Recognize the role of NK cells: Natural Killer (NK) cells are a type of lymphocyte that play a role in the immune response by targeting and destroying virus-infected cells and tumor cells, but they do not perform phagocytosis.

Differentiate between phagocytic and non-phagocytic immune cells: While neutrophils, macrophages, and dendritic cells are phagocytic, NK cells are not involved in phagocytosis.

Conclude that NK cells do not have a direct role in phagocytosis, as their primary function is to induce apoptosis in infected or cancerous cells rather than engulfing them.