This lesson examines conditions in which parts of the immune system are missing or impaired. It compares inherited immunodeficiencies with HIV infection and explains how these conditions affect the body’s defenses.
The immune system relies on many cell types, proteins, and signaling pathways. A mutation affecting even one component can impair a particular defense. The effects vary: some complement deficiencies mainly increase susceptibility to certain Gram-negative bacteria, while other defects cause severe, widespread vulnerability to infection.
All flashcards
What does SCID affect?
SCID impairs both B-cell and T-cell arms of adaptive immunity, increasing vulnerability to infections.
What is seroconversion in HIV infection?
The development of detectable anti-HIV antibodies after infection; its timing varies among individuals.
How does type I hypersensitivity begin?
On re-exposure, an allergen cross-links IgE on sensitized mast cells, triggering degranulation and mediator release.
What distinguishes type III hypersensitivity?
Soluble antigen-antibody complexes deposit in tissues, where they can activate complement and promote inflammation.
What is autoimmunity?
An immune response against the body’s own components that can damage tissues when self-tolerance is lost.
Quiz questions
Which mechanism produces immediate, type I hypersensitivity?Answer: Allergen-specific IgE on mast cells is cross-linked, triggering mediator release.
What causes tissue injury in type III hypersensitivity?Answer: Deposited antigen-antibody complexes activate complement and promote inflammation.
Why do type IV hypersensitivity symptoms commonly take 24 to 72 hours to develop?Answer: Sensitized T cells must initiate a cellular response and recruit other immune cells.
In rheumatic fever, what can antibodies against streptococcal M protein cross-react with?Answer: Heart myosin, potentially contributing to damage to the heart and its valves.
Which mechanism is associated with Graves’ disease?Answer: Antibodies mimic thyroid-stimulating hormone and stimulate its receptor.
Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.