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

Major Histocompatibility Complex Molecules

Anatomy & Physiology

21. The Immune System

Major Histocompatibility Complex Molecules

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Multiple Choice

If an effector CD4 cell encounters an antigen presented on a MHC Class II molecule, how would it respond?

Send signals to the APC trigger apoptosis in the APC.

Engulf the APC and degrade the infected cell and the intracellular pathogen.

Send signals to the APC, activating the APC and triggering an immune response.

All of the following are possible responses of the effector CD4 cell.

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Verified step by step guidance

Understand the role of CD4 cells: CD4 cells, also known as helper T cells, play a crucial role in the immune system by assisting other cells in mounting an immune response.

Recognize the interaction with MHC Class II: CD4 cells specifically interact with antigens presented on MHC Class II molecules, which are found on antigen-presenting cells (APCs) such as dendritic cells, macrophages, and B cells.

Identify the correct response: When a CD4 cell encounters an antigen on an MHC Class II molecule, it does not directly attack or engulf the APC. Instead, it sends signals to the APC.

Explain the signaling process: The CD4 cell releases cytokines, which are signaling molecules that help activate the APC. This activation enhances the APC's ability to present antigens and stimulate other immune cells.

Conclude with the immune response: The activation of the APC by the CD4 cell leads to a more robust immune response, involving the activation of other immune cells such as cytotoxic T cells and B cells, which work together to eliminate the pathogen.