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

Skin tests are used to determine if a person
(a) Has an active infection
(b) Has been exposed to a particular antigen
(c) Carries a particular antigen
(d) Has measles
(e) Can produce antibodies

Verified step by step guidance

Understand the purpose of skin tests: Skin tests are diagnostic tools used to assess the immune system's response to specific antigens. They involve introducing a small amount of antigen into the skin and observing the reaction.

Review the options provided: The question lists several possibilities for what skin tests can determine, including active infection, exposure to antigens, carrying antigens, measles diagnosis, and antibody production.

Clarify the mechanism of skin tests: Skin tests typically measure delayed hypersensitivity reactions, which indicate prior exposure to an antigen and the presence of memory T cells. This is different from detecting active infections or the presence of antibodies.

Eliminate incorrect options: Skin tests do not directly diagnose active infections (a), detect the presence of antigens (c), or diagnose specific diseases like measles (d). They also do not measure antibody production (e), as antibodies are part of the humoral immune response, not the cellular response tested by skin tests.

Conclude the correct answer: Skin tests are primarily used to determine if a person has been exposed to a particular antigen (b), as they rely on the immune system's memory response to the introduced antigen.

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Key Concepts

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

Skin Tests

Skin tests are diagnostic procedures used to assess the immune response to specific antigens. They involve the introduction of a small amount of antigen into the skin, typically through intradermal injection or application. The body's reaction, usually measured by swelling or redness, indicates whether the immune system recognizes the antigen, which can suggest prior exposure or sensitivity.

Antigens

Antigens are substances that provoke an immune response, often proteins found on the surface of pathogens like bacteria and viruses. When introduced into the body, they can trigger the production of antibodies, which are proteins that specifically target and neutralize the antigens. Understanding antigens is crucial for interpreting skin test results, as they help determine if an individual has been exposed to a specific pathogen.

Immune Response

The immune response is the body's defense mechanism against foreign invaders, such as pathogens. It involves the activation of various immune cells and the production of antibodies to eliminate the threat. In the context of skin tests, a positive response indicates that the immune system has previously encountered the antigen, suggesting exposure or infection, which is essential for diagnosing conditions like allergies or infections.

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Related Practice

Textbook Question

The cell type most often invaded by HIV is a(n)

a. Eosinophil

b. Cytotoxic T cell

c. Natural killer cell

d. Helper T cell

e. B cell.

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Textbook Question

The cell type most often invaded by HIV is a(n):

a. Eosinophil

b. Cytotoxic T cell

c. Natural killer cell

d. Helper T cell

e. B cell

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Textbook Question

Caroline, a pregnant 29-year-old, has been HIV-positive for at least 10 years, dating back to when she was homeless and injecting heroin. While she currently has no symptoms of AIDS, she is taking several medications and is worried about the possibility that her baby might be infected. How do you think the HIV virus might be transferred from a mother to her offspring? Which of Caroline’s cells are infected by the virus, and why is the viral attack on these cells so devastating? Why is Caroline taking medication even though she has no symptoms?

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Textbook Question

Which of the following is/are examples of autoimmune disease?

a. Type 1 diabetes

b. Multiple sclerosis

c. Graves’ disease

d. Rheumatoid arthritis

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Textbook Question

While walking along the street, you and your friend see an elderly woman whose left arm appears to be swollen to several times its normal size. Your friend wonders aloud what might be its cause. You say that it may be likely that the woman had a radical mastectomy (the removal of a breast because of cancer). Explain the rationale behind your answer.

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Textbook Question

Willy is allergic to ragweed pollen and tells you that he read about a medication that can help his condition by blocking certain antibodies. Do you think that this treatment could help Willy? Explain.

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Textbook Question

Which of the following conditions may lead to the development of autoimmunity?

a. Self antigens not previously encountered by T cells are released into the circulation

b. Foreign antigens mimic self antigens

c. Cells may inappropriately display class II MHC molecules

d. Certain pathogens nonspecifically activate B cells

e. All of the above are correct

473

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Textbook Question

What are the three classes of lymphocytes, and where does each class originate?