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

Antigens

Anatomy & Physiology

21. The Immune System

Antigens

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Problem 15

Textbook Question

Class I MHC molecules display___antigens and activate_cells. Class II MHC molecules display _antigens and activate___cells.

Verified step by step guidance

Step 1: Understand the role of MHC (Major Histocompatibility Complex) molecules. MHC molecules are proteins found on the surface of cells that play a critical role in the immune system by presenting antigens to immune cells.

Step 2: Learn the distinction between Class I and Class II MHC molecules. Class I MHC molecules are found on all nucleated cells, while Class II MHC molecules are primarily found on antigen-presenting cells such as macrophages, dendritic cells, and B cells.

Step 3: Identify the type of antigens displayed by each class. Class I MHC molecules present endogenous antigens (antigens originating from within the cell, such as viral or tumor antigens), while Class II MHC molecules present exogenous antigens (antigens originating outside the cell, such as bacterial or extracellular pathogens).

Step 4: Determine the type of immune cells activated by each class. Class I MHC molecules activate cytotoxic T cells (CD8+ T cells), which are responsible for killing infected or abnormal cells. Class II MHC molecules activate helper T cells (CD4+ T cells), which assist in coordinating the immune response.

Step 5: Combine the information to understand the complete mechanism: Class I MHC molecules display endogenous antigens and activate cytotoxic T cells, while Class II MHC molecules display exogenous antigens and activate helper T cells.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Class I MHC Molecules

Class I Major Histocompatibility Complex (MHC) molecules are proteins found on the surface of nearly all nucleated cells. They present endogenous antigens, which are typically derived from proteins synthesized within the cell, to CD8+ cytotoxic T cells. This process is crucial for the immune system to recognize and eliminate infected or malignant cells.

Class II MHC Molecules

Class II MHC molecules are primarily expressed on professional antigen-presenting cells, such as dendritic cells, macrophages, and B cells. They present exogenous antigens, which are derived from extracellular sources, to CD4+ helper T cells. This interaction is essential for the activation of helper T cells, which in turn assist in orchestrating the immune response.

T Cell Activation

T cell activation is a critical process in the adaptive immune response, involving the recognition of specific antigens presented by MHC molecules. For CD8+ T cells, activation requires the recognition of Class I MHC-antigen complexes, while CD4+ T cells require Class II MHC-antigen complexes. This activation leads to T cell proliferation, differentiation, and the execution of immune functions, such as killing infected cells or helping other immune cells.