Podcast
Questions and Answers
What is the primary function of antigen-presenting cells (APCs)?
What is the primary function of antigen-presenting cells (APCs)?
Which statement is true regarding MHC Class I molecules?
Which statement is true regarding MHC Class I molecules?
How do antibodies assist in combating pathogens?
How do antibodies assist in combating pathogens?
What role do CD4+ TH cells play in the immune response?
What role do CD4+ TH cells play in the immune response?
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What is the key characteristic of the adaptive immune response?
What is the key characteristic of the adaptive immune response?
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Which cells can be stimulated to become more effective at engulfing and destroying pathogens?
Which cells can be stimulated to become more effective at engulfing and destroying pathogens?
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How do natural killer (NK) cells function in the immune response?
How do natural killer (NK) cells function in the immune response?
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What happens during the clonal expansion of B cells?
What happens during the clonal expansion of B cells?
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Study Notes
Adaptive Immune Response
- Highly specialized, specific defense mechanism for recognizing and fighting foreign pathogens and abnormal cells
- Slower than innate immunity, but has a longer-lasting effect
Specificity
- Targets specific pathogens/abnormal cells based on unique antigens
- Has a memory component, creating memory cells to recognize and respond to an antigen more rapidly if encountered again
Self-Tolerance
- Differentiates between "self" and "non-self" to prevent attacking the body's own cells (autoimmunity)
Antigen Presentation
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Foreign substances presented by antigen-presenting cells (APCs)
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Examples include dendritic cells, macrophages, and B cells
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APCs capture, process, and present antigens to T lymphocytes via major histocompatibility complex (MHC) molecules
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MHC Class I molecules present antigens from intracellular pathogens (e.g., viruses) to CD8+ cytotoxic T cells.
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MHC Class II molecules present antigens from extracellular pathogens (e.g., bacteria) to CD4+ helper T cells.
Humoral Immunity
- Occurs in bodily fluids (e.g., blood, lymph)
- TH cells release cytokines that activate B cells
- Clonal expansion of B cells leads to plasma cells and memory B cells
- Plasma cells produce large quantities of antibodies.
- Antibodies neutralize pathogens, inhibiting their entry into host cells, agglutinating pathogens, activating complement, and enhancing phagocytosis.
- Antibodies can act as opsonins (mark pathogens for phagocytosis).
Cell-Mediated Immunity
- Happens within infected cells
- Dendritic cells, macrophages, and B cells present antigens to T cells on the cell surface via MHC molecules.
- If MHC Class II is present, CD4+ T cells are activated releasing cytokines (e.g., interleukin-2) that enhance the activity of cytotoxic T cells, macrophages, and other immune cells. These cells undergo clonal expansion, producing many T cells specific to the antigen.
- Cytotoxic T cells directly kill infected or abnormal cells by recognizing specific antigens presented by MHC Class I molecules.
- Perforin creates pores in the cell membrane, releasing granzymes to induce apoptosis.
- Natural Killer cells can help target cells missing MHC Class I molecules or with abnormal patterns.
- Activated macrophages are stimulated by cytokines to become more effective at engulfing and destroying pathogens.
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Description
Explore the key concepts of the adaptive immune response, including specificity, self-tolerance, and antigen presentation. Discover how specialized cells identify and combat pathogens while preserving the body's own tissues. This quiz will enhance your understanding of immunology mechanisms.
