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Questions and Answers
What is the primary role of ILC1 and TH1 cells in the immune response?
Which leukocyte type is responsible for mucosal barrier defense against parasites?
What type of pathogens do ILC3 and TH17 cells primarily target?
How do antibodies help combat infections caused by extracellular bacteria that produce toxins?
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What mechanism allows toxin molecules released by bacteria to damage host cells?
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Which toxin is associated with causing fluid loss by affecting sodium-potassium channels?
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What effect does tetanus toxin have on the host's physiological function?
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What consequence would occur if a specific antibody binds to a bacterial toxin?
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Which type of pathogen is categorized as intracellular?
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Which pathogen is known to grow inside red blood cells (RBC)?
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What type of immune cells are primarily responsible for cytotoxicity against viruses?
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Which of the following is an extracellular pathogen?
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What is the specific receptor found on cytotoxic T cells?
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Which type of pathogen is primarily handled by antibodies and cytotoxic T cells?
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Which condition is caused by Leishmania donovani?
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What type of T cell is referred to as CD4 cells?
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What is the process called when antibodies bind to a toxin to prevent it from causing damage?
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Which process involves antibodies coating bacteria to enhance their removal by immune cells?
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How does complement activation contribute to the immune response?
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What will happen if bacteria still grow in the body after the innate immunity response is insufficient?
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Which statement correctly describes one characteristic of the complement proteins?
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What happens when antibodies coat bacteria?
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Which of the following is NOT one of the main functions of antibodies as described?
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What is the role of macrophages in the immune response to bacteria?
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What role do tonsils play in the immune response to infections in the throat?
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What is the specialized immune structure found in the mucosal region that helps fight infections?
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What are the various types of associated lymphoid tissue mentioned?
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How do macrophages and dendritic cells respond to infections?
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What happens to T cells after they are activated in response to an infection?
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What immediate response occurs after an infection in the body?
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What unique feature is characteristic of M cells?
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Which immune cells are primarily involved in the interaction at the lymph node during an immune response?
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What role do macrophages play in the immune response?
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How do macrophages recognize pathogens for engulfment?
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What is opsonization in the context of immune defense?
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What occurs during complement activation in relation to bacteria?
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What is the primary outcome of phagocytosis performed by macrophages?
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What happens to a bacterial cell when a complement protein forms a channel in its membrane?
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Which of the following statements about antibody functions is accurate?
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Which immune mechanism is highlighted as a way to manage microbial infections?
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Study Notes
Immune System Response to Infection
- Tonsils: Act as a local defense system for the mouth, throat, and surrounding areas.
- Lymph Nodes: In the absence of tonsils, lymph nodes take care of infections in mucosal regions.
- Mucosal Associated Lymphoid Tissue (MALT): Composed of specialized immune structures that handle infections in mucosal regions lacking direct blood connections.
- MALT includes: tonsils, adenoids, appendix, Peyer's patches, nasal associated lymphoid tissue (NALT), and bronchus associated lymphoid tissue (BALT).
- M Cells: Specialized cells within MALT that handle infection; they have membrane ruffles and are packed with T cells and dendritic cells.
Primary and Adaptive Immunity
- Innate Immunity: First line of defense; inflammatory response brings the infection to the nearest lymph node.
- Adaptive Immunity: Activated T cells help activate B cells to produce antibodies.
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Pathogen Types:
- Intracellular pathogens: Viruses, intracellular bacteria (e.g. Listeria), protozoan parasites (e.g. Leishmania donovani).
- Extracellular pathogens: Extracellular bacteria (e.g. Streptococci, Clostridia), fungi, parasitic worms.
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Antibody Response to Pathogens:
- Viruses: Taken care of by NK cells and CD8 T cells (cytotoxic T cells) through cytotoxicity (elimination of infected cells).
- Intracellular bacteria or parasites: Eliminated by ILC1 (innate leukocyte 1) and TH1 cells through macrophage activation.
- Mucosal pathogens: Taken care of by ILC2, or Group 2 Innate Lymphoid Cells, play a crucial role in the immune response to mucosal pathogens, particularly those associated with allergic reactions and parasitic infections. Unlike conventional T cells, ILC2s do not recognize specific antigens but are activated by cytokines released during the early stages of infection. They secrete a variety of cytokines, such as IL-4, IL-5, and IL-13, which promote the recruitment and activation of other immune cells, including eosinophils and basophils. This activity facilitates the expulsion of pathogens from the host and contributes to the regulation of tissue homeostasis. Furthermore, ILC2s are also involved in the development of type 2 immune responses, which are critical for combating helminth infections as well as in the pathogenesis of allergic diseases like asthma.and TH2 cells (effected function includes elimination and expulsion of parasites, recruitment of eosinophils, basophils, and mast cells for infection handling).
- Extracellular bacteria and fungi: Eliminated by ILC3 and TH17 cells, recruitment, and activation of neutrophils (involved in innate immunity).
Antibody Actions
- Neutralization: Antibodies bind to toxins, preventing them from binding to cell receptors and causing damage. This process renders the toxin inactive.
- Opsonization: Antibodies coat bacteria, making them easier for macrophages to phagocytose and destroy. This process enhances phagocytosis.
- Complement Activation: Antibodies trigger the complement system, a series of proteins in the blood that create pores in bacterial membranes, leading to cell lysis.
Complement System
- Functions: Part of innate immunity, nonspecific, highly effective in killing other mammalian cells, but does not harm the organism it belongs to.
- Specificity: An organism's complement system does not harm its own cells, but can harm cells from other organisms.
- Mechanism: Complement proteins bind to bacteria coated with antibodies, forming a channel that disrupts the cell membrane.
Macrophage Function in Antibody Actions
- Neutralization: Macrophages have receptors for antibodies, which bind to antibody-toxin complexes. This initiates phagocytosis, engulfing and degrading the toxins.
- Opsonization: Macrophages phagocytose bacteria coated with antibodies, effectively removing them from the body.
Summary
- Antibodies play a critical role in defeating infections by neutralizing toxins, enhancing phagocytosis, and activating the complement system.
- The immune system uses different strategies to fight intracellular and extracellular pathogens.
- Understanding the different mechanisms of antibody action is crucial for developing successful therapies against infectious diseases.
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Description
Explore the fundamentals of the immune system's response to infections, including the roles of tonsils, lymph nodes, and mucosal associated lymphoid tissue (MALT). Understand the distinctions between innate and adaptive immunity, and how these systems work together to protect the body from pathogens.
