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Questions and Answers
What is the primary effect of fever on pathogens during an immune response?
Which immune response is activated when the nonspecific innate immune response is insufficient?
How do Helper T cells contribute to the immune response?
What physiological response occurs when a fever breaks?
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Which type of T cell is responsible for killing virus-infected cells?
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What can high fevers above 42 °C (108 °F) lead to if not managed properly?
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What is the role of antibodies produced by B cells?
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What is a consequence of the vasoconstriction of blood vessels during fever?
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What is the primary function of Regulatory T Cells (Tregs)?
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Which statement accurately describes the memory function in specific adaptive immunity?
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What does clonal expansion refer to in the context of adaptive immunity?
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How does the adaptive immune system achieve diversity?
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What is a potential consequence of the failure of self-tolerance in the immune system?
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Which type of immunity involves B cells producing antibodies?
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What distinguishes specific adaptive immunity from innate immunity?
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What role do Cytotoxic T Cells (CD8+ T Cells) play in the immune response?
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What is the primary function of cytotoxic T cells in the cell-mediated immune response?
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What role do helper T cells play in the immune response?
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Which of the following statements accurately describes the humoral immune response?
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What is the first stage of the adaptive immune response?
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What distinguishes cell-mediated immunity from humoral immunity?
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Which of the following is NOT a characteristic of the humoral immune response?
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Which pathogens are primarily targeted by the cell-mediated immune response?
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What occurs during the clonal expansion stage of the adaptive immune response?
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Study Notes
Specific Adaptive Immunity
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Key Features:
- Specificity: Targets specific antigens on pathogens. B cells and T cells have receptors designed to recognize these unique molecules, leading to a precise immune response.
- Memory: After exposure to a pathogen, the immune system creates memory cells (both B and T cells). These cells "remember" the pathogen, allowing for a faster and stronger response upon future encounters.
- Clonal Expansion: Once B cells or T cells recognize an antigen, they rapidly multiply, creating clones of themselves to fight the infection more effectively.
- Diversity: The adaptive immune system has a vast array of receptors, allowing it to recognize millions of different antigens and respond to a wide variety of pathogens.
- Self-Tolerance: The immune system is designed to distinguish between "self" and "non-self". It usually avoids attacking the body’s own cells, preventing autoimmune reactions. Failure of self-tolerance can lead to autoimmune diseases, where the immune system mistakenly attacks healthy cells.
Two Main Branches of Adaptive Immunity
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Humoral Immunity (B cell-mediated immunity):
- B cells are responsible for the humoral immune response, where they produce antibodies to target pathogens in body fluids (such as blood and lymph).
- Antibodies bind to specific antigens on pathogens, neutralizing them and marking them for destruction by other immune cells or the complement system.
- Effective against extracellular pathogens (bacteria, toxins, and viruses outside of cells).
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Cell-Mediated Immunity (T cell-mediated immunity):
- T cells are responsible for the cell-mediated immune response, particularly cytotoxic T cells (CD8+ T cells), which directly destroy infected, cancerous, or foreign cells.
- Helper T cells (CD4+ T cells) play a supporting role by releasing cytokines to activate other immune cells, including B cells and cytotoxic T cells.
- Effective against intracellular pathogens (viruses, bacteria, and cancer cells inside the body's own cells).
Summary
- Feature | Cell-Mediated Response | Humoral Response
- --- | --- | ---
- Primary cells involved | T cells (cytotoxic and helper T cells) | B cells (with helper T cell support)
- Main mechanism | Direct killing of infected or abnormal cells | Antibodies neutralize and tag pathogens
- Target | Intracellular pathogens (e.g., viruses), cancer cells | Extracellular pathogens (e.g., bacteria, toxins)
- Role of antibodies | Not involved | Central to the response
- Example of response | Defense against virus-infected cells | Neutralization of bacteria in the bloodstream
Stages of the Adaptive Immune Response:
- Recognition of Antigens: B cells and T cells have unique receptors that can bind to specific antigens presented by pathogens or infected cells.
- Activation of Lymphocytes: Once an antigen is recognized, the specific B or T cell is activated, often with the help of helper T cells.
- Clonal Expansion: Activated B and T cells rapidly divide to produce many clones of themselves to effectively target the pathogen.
- Elimination of Pathogens: Antibodies from B cells neutralize pathogens in body fluids, while cytotoxic T cells kill infected or abnormal cells.
T Cells
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Helper T Cells (CD4+ T Cells)
- Activate and coordinate the immune response by activating other immune cells.
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Regulatory T Cells (Tregs)
- Maintain immune tolerance and prevent autoimmune responses by suppressing excessive immune activity.
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Cytotoxic T Cells (CD8+ T Cells)
- Directly kill infected or abnormal cells by recognizing and destroying them.
Fever
- Fever enhances the nonspecific innate immune defenses by stimulating white blood cells to kill pathogens.
- The rise in body temperature also inhibits the growth of many pathogens.
- During fever, the patient’s skin may appear pale due to vasoconstriction of the blood vessels in the skin to divert blood flow away from extremities, minimize the loss of heat, and raise the body’s core temperature.
- The hypothalamus also stimulates the shivering of muscles to generate heat and raise the core temperature.
- A low-level fever is thought to help an individual overcome an illness.
- In some instances, this immune response can be too strong, causing tissue and organ damage and, in severe cases, even death.
- Example: Staphylococcus aureus and Streptococcus pyogenes are capable of producing superantigens that cause toxic shock syndrome and scarlet fever, respectively.
- Both of these conditions are associated with extremely high fevers in excess of 42 °C (108 °F) that must be managed to prevent tissue injury and death.
- When a fever breaks, the hypothalamus stimulates vasodilation, resulting in a return of blood flow to the skin and a subsequent release of heat from the body. The hypothalamus also stimulates sweating, which cools the skin as the sweat evaporates.
Specific adaptive immunity
- Specific adaptive immunity is the immune response that is activated when the nonspecific innate immune response is insufficient to control an infection.
- There are 2 types of adaptive responses:
- Cell-mediated immune response, which is carried out by T cells.
- Humoral immune response, which is controlled by activated B cells and antibodies.
- T cells- Immune cells that mature in the thymus.
- T cells are categorized into three classes:
- Helper T cells
- Regulatory T cells
- Cytotoxic T cells.
- B cells- Immune cells that mature in the bone marrow and produce antibodies.
- The five classes of antibodies are IgG, IgM, IgA, IgD, and IgE. They also turn into memory B cells.
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Description
This quiz covers the key features of specific adaptive immunity, including its mechanisms such as specificity, memory, clonal expansion, diversity, and self-tolerance. Test your knowledge on how the immune system effectively targets pathogens while maintaining a balance to avoid attacking the body's own cells.
