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

Immune Tolerance

Anatomy & Physiology

21. The Immune System

Immune Tolerance

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Problem 19

Textbook Question

Explain why a patient with AIDS due to HIV is at an increased risk of infection and of developing certain cancers.

Verified step by step guidance

Understand the role of the immune system: The immune system is responsible for defending the body against infections and abnormal cell growth, including cancer. Key components include white blood cells, such as T cells, which coordinate immune responses.

Learn how HIV affects the immune system: HIV specifically targets and destroys CD4+ T cells, a type of white blood cell crucial for immune function. This leads to a weakened immune system, known as immunodeficiency.

Recognize the progression to AIDS: When the number of CD4+ T cells drops below a critical threshold, the patient is diagnosed with AIDS (Acquired Immunodeficiency Syndrome). At this stage, the immune system is severely compromised.

Understand the increased risk of infection: With fewer CD4+ T cells, the body cannot effectively fight off pathogens, making the patient more susceptible to opportunistic infections, which are infections that occur more frequently or are more severe in individuals with weakened immune systems.

Explain the link to cancer: The immune system also plays a role in identifying and destroying abnormal cells that could develop into cancer. A weakened immune system in AIDS patients reduces this surveillance, increasing the risk of certain cancers, such as Kaposi's sarcoma and non-Hodgkin lymphoma.

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Key Concepts

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

HIV and the Immune System

HIV (Human Immunodeficiency Virus) attacks the immune system, specifically targeting CD4 T cells, which are crucial for coordinating the body's immune response. As the virus progresses, it leads to a decrease in these cells, weakening the immune system's ability to fight off infections and diseases, making individuals more susceptible to opportunistic infections and certain cancers.

Opportunistic Infections

Opportunistic infections are infections that occur more frequently and are more severe in individuals with weakened immune systems, such as those with AIDS. Common examples include pneumonia, tuberculosis, and certain fungal infections, which take advantage of the compromised immune defenses in patients with low CD4 counts, leading to increased morbidity and mortality.

Cancer Risk in Immunocompromised Patients

Patients with AIDS are at a higher risk of developing certain cancers, known as AIDS-related cancers, due to their compromised immune systems. The lack of effective immune surveillance allows for the proliferation of cancerous cells and the reactivation of oncogenic viruses, such as Kaposi's sarcoma-associated herpesvirus and Epstein-Barr virus, which are linked to specific malignancies in these patients.

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