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Questions and Answers

What is the predominant function of the complement system in immune response?

  • To promote inflammation and pathogen lysis (correct)
  • To enhance phagocyte mobility
  • To produce antibodies against pathogens
  • To stimulate B cell maturation

Which type of cytokine is primarily involved in stimulating a wide range of immune system functions?

  • Interferons
  • Interleukins (correct)
  • Chemokines
  • Acute-phase proteins

What is one of the key roles of interferons in innate immunity?

  • Facilitate blood clotting
  • Stimulate the production of B cells
  • Enhance natural killer cell activity
  • Inhibit viral RNA replication (correct)

Which cell type is integral for connecting innate immunity with adaptive immunity?

<p>Dendritic cells (D)</p> Signup and view all the answers

What characterizes the lifespan of neutrophils during an immune response?

<p>Short lifespan and immediate response (B)</p> Signup and view all the answers

What is the primary effect of vasodilation during inflammation?

<p>Fluid accumulation leading to edema (C)</p> Signup and view all the answers

Which process is responsible for marking pathogens for effective phagocytosis?

<p>Opsonization (C)</p> Signup and view all the answers

What do pyrogens directly influence in the immune response?

<p>Induction of fever by acting on the hypothalamus (C)</p> Signup and view all the answers

Which acute-phase protein plays a vital role in sequestering iron to limit pathogen growth?

<p>Ferritin (C)</p> Signup and view all the answers

Which type of immune cell is specialized for long-term phagocytosis and originates from monocytes?

<p>Macrophages (D)</p> Signup and view all the answers

Which of the following best describes fomites in the context of disease transmission?

<p>Inanimate objects that can transmit infections (C)</p> Signup and view all the answers

Which statement accurately describes a passive carrier of disease?

<p>Person who exhibits no symptoms but spreads the pathogen (C)</p> Signup and view all the answers

Active carriers of disease are characterized by which of the following?

<p>Being actively infected and capable of transmission (C)</p> Signup and view all the answers

What best defines a mechanical vector in disease transmission?

<p>An insect that carries pathogens without being infected (C)</p> Signup and view all the answers

Who is recognized for establishing key principles in detecting cholera outbreaks and is referred to as the father of epidemiology?

<p>John Snow (B)</p> Signup and view all the answers

Which term signifies the ongoing presence of a disease within a certain population?

<p>Endemic (D)</p> Signup and view all the answers

What can result from significant failures in public health systems?

<p>Increased cases of emerging infectious diseases (A)</p> Signup and view all the answers

A localized epidemic, particularly in a specific community, is commonly termed as what?

<p>Outbreak (A)</p> Signup and view all the answers

What does the term 'herd immunity' refer to in population health?

<p>Immunity achieved by the majority of the population being vaccinated (C)</p> Signup and view all the answers

Which of the following best illustrates zoonotic transmission?

<p>Rabies transmitted through a dog bite (D)</p> Signup and view all the answers

What distinguishes innate immunity from acquired immunity?

<p>Innate immunity is nonspecific and inborn. (B)</p> Signup and view all the answers

Which physical barrier is primarily responsible for the protection of internal mucosal surfaces?

<p>Mucosal membranes (B)</p> Signup and view all the answers

Which function does lactoferrin perform in the context of innate immunity?

<p>Sequesters iron to inhibit microbial growth (D)</p> Signup and view all the answers

In which way does the human skin function as a physical barrier in innate immunity?

<p>By forming a thick keratinized layer to prevent entry of pathogens (B)</p> Signup and view all the answers

Which of the following best describes the role of microbiota in human immune defense?

<p>Competes with pathogens for resources, reducing colonization (A)</p> Signup and view all the answers

What is the primary mechanism by which defensins function in innate immunity?

<p>Disrupting the integrity of microbial membranes (C)</p> Signup and view all the answers

What is the main purpose of opsonins in the immune response?

<p>To coat pathogens for enhanced phagocytosis (A)</p> Signup and view all the answers

Which of the following enzymes specifically breaks down peptidoglycan in bacterial cell walls?

<p>Lysozyme (A)</p> Signup and view all the answers

How do cytokines function within the immune response?

<p>They act as signaling molecules for communication between cells. (C)</p> Signup and view all the answers

What is the role of dermicidin in innate immunity?

<p>To disrupt the integrity of pathogen membranes (D)</p> Signup and view all the answers

Which statement correctly describes a definitive host in relation to a parasite?

<p>It is where the parasite reaches its maturity. (C)</p> Signup and view all the answers

Which method of disease transmission involves direct transfer of pathogens from person to person?

<p>Horizontal transmission through respiratory droplets. (C)</p> Signup and view all the answers

What role do acute phase proteins play in the immune response?

<p>They sequester iron to inhibit pathogen growth. (B)</p> Signup and view all the answers

Which cellular component is primarily responsible for the initial response to infection?

<p>Neutrophils, which are the first responders. (C)</p> Signup and view all the answers

Which term refers to the competition for nutrients and space between microbiota and pathogens?

<p>Microbial antagonism. (D)</p> Signup and view all the answers

What is a primary function of cytokines during an immune response?

<p>To signal and recruit immune cells to the site of infection. (A)</p> Signup and view all the answers

Which characteristic distinguishes biological vectors in disease transmission?

<p>They can harbor the pathogen within themselves. (B)</p> Signup and view all the answers

Which physiological response occurs following the release of cytokines by macrophages during inflammation?

<p>Capillary walls dilate to allow plasma flow. (C)</p> Signup and view all the answers

What is the primary consequence of forming a fibrin clot during inflammation?

<p>Prevents the spread of infection. (C)</p> Signup and view all the answers

Which of the following best describes the innate immune system?

<p>It consists of pre-existing defenses that are nonspecific. (C)</p> Signup and view all the answers

Which term describes a passive carrier in epidemiology?

<p>Harbors pathogens without displaying any symptoms (B)</p> Signup and view all the answers

What term best describes the ongoing presence of a disease in a population?

<p>Endemic (B)</p> Signup and view all the answers

Which of the following is a characteristic of active carriers?

<p>Actively exhibiting symptoms of the disease (D)</p> Signup and view all the answers

A disease that occurs at greater than expected levels in a geographic area over a short period is termed what?

<p>Epidemic (D)</p> Signup and view all the answers

Which of the following best defines a vehicle transmission?

<p>Spread of disease through contaminated food or water (B)</p> Signup and view all the answers

Which individual is recognized as the 'father of epidemiology' for his work during cholera outbreaks?

<p>John Snow (A)</p> Signup and view all the answers

What type of immunity is referred to when a majority of a population is immune to a disease?

<p>Herd immunity (A)</p> Signup and view all the answers

Which transmission mode involves pathogens carried through the air in small droplets?

<p>Aerosol transmission (C)</p> Signup and view all the answers

Which factor commonly leads to the resurgence of diseases globally?

<p>Urbanization and crowded living conditions (C)</p> Signup and view all the answers

Which pathogen transmission method is characterized by indirect contact through surfaces?

<p>Fomite transmission (A)</p> Signup and view all the answers

What is the primary function of macrophages in the immune system?

<p>To link innate and adaptive immunity (B)</p> Signup and view all the answers

Which of the following processes is primarily responsible for the clearance of dead cells during inflammation?

<p>Phagocytosis by macrophages (B)</p> Signup and view all the answers

Which type of signaling do chemokines predominantly utilize to facilitate immune responses?

<p>Paracrine signaling (B)</p> Signup and view all the answers

What role does vasodilation play during inflammation?

<p>Increases the permeability of blood vessels (B)</p> Signup and view all the answers

Which of the following best describes the function of dendritic cells?

<p>Antigen presentation to T cells (C)</p> Signup and view all the answers

What is the primary role of interleukins in the immune response?

<p>To modulate the intensity of immune responses (A)</p> Signup and view all the answers

Which of these is NOT a function of NK cells?

<p>Antigen presentation to T cells (B)</p> Signup and view all the answers

Which acute-phase protein primarily acts by binding free hemoglobin to limit inflammation during infection?

<p>Haptoglobin (D)</p> Signup and view all the answers

What is the function of opsonins during phagocytosis?

<p>To mark pathogens for recognition and engulfment (C)</p> Signup and view all the answers

What defines the term 'endemic' in relation to diseases?

<p>Consistent presence within a particular geographic area (C)</p> Signup and view all the answers

What are the two primary features that distinguish innate immunity from acquired immunity?

<p>Nonspecific response and rapid response (B)</p> Signup and view all the answers

What unique role does lactoferrin play in innate immunity apart from its antimicrobial properties?

<p>It sequesters iron to limit pathogen access. (D)</p> Signup and view all the answers

Which chemical barrier is specifically known for disrupting bacterial cell membranes?

<p>Defensins (B)</p> Signup and view all the answers

How do mucosal membranes primarily enhance the body's defense mechanisms?

<p>By covering internal surfaces and secreting mucus. (D)</p> Signup and view all the answers

Which of the following best describes the action of lysozyme in the immune system?

<p>It cleaves peptidoglycan in bacterial cell walls. (D)</p> Signup and view all the answers

What describes the role of microbiota in defending against pathogens?

<p>They compete with pathogens for resources and space. (C)</p> Signup and view all the answers

Which statement describes the main role of C-reactive protein in innate immunity?

<p>Coating pathogens to facilitate phagocytosis. (C)</p> Signup and view all the answers

Which feature of skin makes it an effective physical barrier in innate immunity?

<p>The production of antimicrobial peptides in skin layers. (C)</p> Signup and view all the answers

What is the primary function of dermicidin in the skin?

<p>Disrupting microbial membrane integrity. (D)</p> Signup and view all the answers

What characteristic of acquired immunity is lacking in innate immunity?

<p>Ability to remember past infections. (D)</p> Signup and view all the answers

What characterizes the secondary immune response compared to the primary immune response?

<p>Dominated by IgG production (D)</p> Signup and view all the answers

Which cells are involved in humoral immunity?

<p>B cells (D)</p> Signup and view all the answers

What is the role of memory cells in the adaptive immune system?

<p>Provide a faster response upon re-exposure (B)</p> Signup and view all the answers

Which antibody class is primarily involved in mucosal immunity?

<p>IgA (B)</p> Signup and view all the answers

What is the primary function of the Fab region of an antibody?

<p>Recognize and bind to antigens (B)</p> Signup and view all the answers

Which type of T cell is primarily involved in helping B cells produce antibodies?

<p>Helper T cells (TH2) (A)</p> Signup and view all the answers

Clonal selection leads to the formation of which types of cells?

<p>Effector cells and memory cells (A)</p> Signup and view all the answers

In terms of structure, how are antibodies primarily organized?

<p>Two heavy chains and two light chains linked by disulfide bonds (C)</p> Signup and view all the answers

What characterizes the primary immune response?

<p>IgM appears first, followed by IgG (B)</p> Signup and view all the answers

What is the main function of memory cells in the adaptive immune response?

<p>To provide future protection by generating antibodies quickly (C)</p> Signup and view all the answers

What is the primary function of cytotoxic T cells (CTLs)?

<p>Eliminate infected or tumor cells (A)</p> Signup and view all the answers

Which class of antibodies indicates a primary immune response?

<p>IgM (A)</p> Signup and view all the answers

Which type of T cell is primarily responsible for regulating immune responses?

<p>Helper T Cells (C)</p> Signup and view all the answers

Which statement correctly describes a characteristic of IgD?

<p>Acts as a receptor on B cells (B)</p> Signup and view all the answers

What is the function of the Fab region of an antibody?

<p>To provide a site for antigen binding (D)</p> Signup and view all the answers

Which of the following is considered an example of artificial active immunity?

<p>Vaccination (C)</p> Signup and view all the answers

Which type of immunity is primarily involved in identifying and destroying virus-infected cells?

<p>Cellular Immunity (D)</p> Signup and view all the answers

Which antibody class is typically associated with the first immune response and has 10 binding sites?

<p>IgM (C)</p> Signup and view all the answers

Which statement about the role of B cells in the immune system is accurate?

<p>B cells produce antibodies against specific antigens (D)</p> Signup and view all the answers

What distinguishes IgA from other classes of antibodies?

<p>It is involved in mucosal immunity (D)</p> Signup and view all the answers

What describes the clonal selection process in adaptive immunity?

<p>Specific receptors on immune cells bind to antigens, leading to selective proliferation (D)</p> Signup and view all the answers

What type of vaccine contains inactivated toxins and requires boosters?

<p>Toxoid vaccines (C)</p> Signup and view all the answers

Which type of vaccine combines weak antigens with strong ones to enhance the immune response?

<p>Conjugate vaccines (A)</p> Signup and view all the answers

What defines passive immunity?

<p>The body acquires antibodies from another source (A)</p> Signup and view all the answers

Which vaccines require the recipient to receive booster shots for sustained immunity?

<p>Both B and C (A)</p> Signup and view all the answers

Which of the following describes natural active immunity?

<p>Acquiring immunity after an infection (D)</p> Signup and view all the answers

What is the main characteristic of live, attenuated vaccines?

<p>Contain weakened microbes (B)</p> Signup and view all the answers

What is the primary mechanism through which subunit vaccines operate?

<p>Utilize antigen fragments to provoke immunity (A)</p> Signup and view all the answers

Which type of immunity typically develops as a result of vaccination?

<p>Active immunity (B)</p> Signup and view all the answers

What is the role of maternal antibodies in passive immunity?

<p>They are transferred through the placenta or breastmilk (A)</p> Signup and view all the answers

Which type of vaccine primarily targets the immune response by using fragments of pathogens?

<p>Subunit vaccines (D)</p> Signup and view all the answers

Which of the following statements about inactivated vaccines is correct?

<p>They require booster shots due to killed pathogens (B)</p> Signup and view all the answers

Which option correctly characterizes conjugate vaccines?

<p>Combine weak antigens with stronger carriers to enhance response (C)</p> Signup and view all the answers

How is artificial passive immunity typically acquired?

<p>By injection of pre-formed antibodies (C)</p> Signup and view all the answers

Which of the following describes the main advantage of using live, attenuated vaccines?

<p>They elicit a strong and lasting immune response (B)</p> Signup and view all the answers

Flashcards

Pathogenicity

The ability of a pathogen to cause disease.

Virulence

The degree to which a pathogen can cause disease.

Antigen

A molecule or structure on a pathogen recognized by the immune system.

Antibody

A protein produced by B cells that specifically binds to an antigen.

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Phagocytosis

The process of immune cells engulfing and destroying foreign particles.

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Inflammation

A localized reaction in the body characterized by redness, swelling, heat, and pain.

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Complement system

A group of proteins that circulate in the blood and can be activated to destroy pathogens.

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Chemokine

A type of cytokine that attracts white blood cells to the site of infection.

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Cytokine

Proteins released by immune cells that signal other cells to respond to infection.

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Neutrophil

A type of cell that is a first responder to infection and has a short lifespan.

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Innate Immunity

The body's first line of defense against pathogens. It is nonspecific, meaning it targets a wide range of pathogens without prior exposure.

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Acquired Immunity

A type of immunity that is specific to a particular pathogen. It develops after exposure to the pathogen, and it involves memory cells that can quickly recognize and eliminate the pathogen upon re-exposure.

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Skin as a Barrier

The outermost layer of skin acts as a physical barrier, preventing pathogens from entering the body. It is also constantly shedding, removing microbes.

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Mucosal Membranes

These membranes line the respiratory, digestive, and reproductive tracts, trapping and removing pathogens. They also secrete mucus, which traps microbes.

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Microbiota Role in Immunity

The normal microbiota, a diverse community of microbes that live on and in the body, competes with pathogens for resources and space, preventing them from establishing infections.

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Lysozyme

An enzyme found in tears, saliva, and other bodily fluids. It breaks down peptidoglycan in the cell wall of Gram-positive bacteria, weakening their structure.

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Lactoferrin

This protein binds to iron, making it unavailable to bacteria, which need iron to grow and multiply.

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Dermicidin

A small peptide secreted by sweat glands. It disrupts the membrane integrity of bacteria, leading to their death.

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Opsonins

A group of proteins in the blood that bind to pathogens and mark them for phagocytosis by immune cells.

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C-reactive Protein

A protein in the blood that binds to the surface of bacteria and activates the complement cascade, a series of reactions that leads to pathogen destruction.

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What are fomites?

Inanimate objects, such as doorknobs, utensils, or surfaces, that can harbor and transmit pathogens.

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What is a vector?

A living organism, often an insect, that transmits pathogens from one host to another.

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What is vehicle transmission?

The transmission of a pathogen through contaminated food or water.

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What is vertical transmission?

The transmission of pathogens from a mother to her offspring during pregnancy, childbirth, or breastfeeding.

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What is a passive carrier?

A person who harbors and transmits a pathogen without showing symptoms of the disease.

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What is an active carrier?

An individual who is actively infected with a pathogen and can transmit it to others.

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What is epidemiology?

The study of how diseases spread and affect populations.

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What is incidence?

The number of new cases of a disease in a given time period.

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What are nosocomial infections?

Healthcare-associated infections are infections acquired in a healthcare setting.

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What is an outbreak?

A localized epidemic, involving a cluster of cases in a specific area.

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What is the function of the immune system?

The immune system's primary function is to protect the body from pathogens, such as bacteria, viruses, and parasites.

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What is innate immunity?

Innate immunity is the body's first line of defense, acting as a nonspecific, inborn defense system against a broad range of pathogens.

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What is the primary feature of acquired immunity?

Acquired immunity, also known as adaptive immunity, is a specific, targeted immune response that develops after exposure to a pathogen, and involves the formation of memory cells that can quickly respond to the same pathogen upon re-exposure.

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Which of the following is a physical barrier in innate immunity?

Physical barriers like skin and mucosal membranes are the first line of defense in innate immunity, preventing pathogens from directly entering the body.

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How do mucosal membranes contribute to immunity?

Mucosal membranes, lining internal tracts like the respiratory, digestive, and reproductive systems, act as physical barriers that trap and remove pathogens. They also secrete mucus, which catches microbes.

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What is the role of microbiota in innate immunity?

The normal microbiota, a diverse community of microbes living on and in the body, helps in innate immunity by competing with pathogens for resources and space, preventing them from establishing infections.

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Which enzyme targets Gram-positive bacteria by breaking down peptidoglycan?

Lysozyme, an enzyme present in tears, saliva, and other bodily fluids, targets Gram-positive bacteria by breaking down peptidoglycan in their cell walls, weakening their structure.

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What is the role of lactoferrin in innate immunity?

Lactoferrin, a protein in body fluids, helps by sequestering iron, making it unavailable to pathogens, which rely on iron for growth and multiplication.

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Which antimicrobial peptide is secreted by sweat glands and disrupts membrane integrity?

Dermicidin, an antimicrobial peptide secreted by sweat glands, helps by disrupting the membrane integrity of bacteria, leading to their death.

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Which plasma protein coats bacteria to prepare them for ingestion?

Mannose-binding lectin, a plasma protein, coats bacteria to prepare them for ingestion by phagocytic cells.

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Immunity

Body's ability to resist disease.

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Immune system

Collection of cells, tissues, and molecules that protect the body from pathogens.

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Immunology

Scientific study of how the immune system functions.

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First line of defense

A nonspecific defense mechanism that prevents pathogens from entering the body.

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Physical Barriers

This includes skin and mucous membranes.

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Second line of defense

Involves white blood cells, inflammation, and antimicrobial substances.

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Third line of defense

This involves antigens specific to the pathogen.

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Enzymatic Mediators

Substances like lysozyme in tears and saliva that break down bacteria.

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Primary Immune Response

The initial immune response to a pathogen, characterized by a lower concentration of antibodies, with IgM appearing first, followed by IgG.

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Secondary Immune Response

A faster, more powerful immune response upon re-exposure to a pathogen, characterized by higher levels of IgG.

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Humoral Immunity

A type of adaptive immunity that involves the production of antibodies by B cells to neutralize pathogens in body fluids.

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Cellular Immunity

A type of adaptive immunity that involves T cells destroying infected or abnormal cells.

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Epitopes

Regions on antigens recognized by specific B and T cell receptors.

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Clonal Selection

The process by which B and T cells specific to an antigen are activated and proliferate.

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Effector Cells

Cells that directly target and eliminate pathogens during an immune response.

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Memory Cells

Long-lived B and T cells that provide a faster and stronger immune response upon re-exposure to the same pathogen.

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Active Immunity

A type of immunity where the body produces its own antibodies in response to encountering a pathogen, either through infection or vaccination.

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Passive Immunity

A type of immunity acquired through receiving antibodies from another person, either naturally through maternal antibodies or artificially through antibody injections.

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Live, Attenuated Vaccines

A type of vaccine that contains weakened forms of the pathogen, triggering a strong immune response but without causing disease.

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Inactivated Vaccines

A type of vaccine that contains killed pathogens, requiring booster doses to maintain long-term immunity.

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Subunit Vaccines

Vaccines that contain only specific parts of the pathogen, such as antigen fragments, preventing the risk of disease.

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Conjugate Vaccines

A type of vaccine that combines a weak antigen with a stronger one to boost the immune response.

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Toxoid Vaccines

A type of vaccine that contains inactivated toxins, requiring booster doses for long-term immunity.

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What is the function of cytotoxic T cells (CTLs)?

Cytotoxic T cells (CTLs) are a type of lymphocyte that directly kill infected or cancerous cells by releasing cytotoxic substances like granzyme and perforin.

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What is a characteristic of IgD?

IgD is a type of antibody that primarily acts as a receptor on the surface of B cells, playing a role in B cell activation and differentiation.

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What is an example of artificial active immunity?

Artificial active immunity is achieved through vaccination, where a weakened or inactivated form of the pathogen or its components are introduced to the body, stimulating the immune system to create long-lasting protection against the disease.

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Which antibody class is associated with the first immune response and has 10 binding sites?

IgM is the first antibody class produced during an immune response. It has 10 binding sites due to its pentameric structure, allowing it to effectively neutralize pathogens and activate the complement system.

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What is vaccination?

Vaccination is the process of introducing a weakened or inactive form of a pathogen or its components into the body to stimulate the immune system and produce long-lasting protection against the disease.

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Study Notes

Innate Non-Specific Host Defenses

  • Protect the body from pathogens.
  • Innate Immunity: A nonspecific, inborn defense system.
  • Acquired Immunity: A highly specific immune response with memory.
  • Physical Barriers: Skin, mucosal membranes, and microbiota.
  • Mucosal Membranes: Line and protect internal tracts, contributing to immunity.
  • Microbiota: Compete with pathogens for nutrients and space, aiding innate immunity.
  • Lysozyme: Enzyme that breaks down peptidoglycan in Gram-positive bacteria.
  • Lactoferrin: Sequesters iron, inhibiting pathogen growth.
  • Antimicrobial Peptides (e.g., Dermicidin, Defensins, Cathelicidin, Histatins): Disrupt pathogen membranes.
  • Complement System: Promotes inflammation and pathogen lysis.
  • Cytokines (e.g., Interferons, Chemokines, Interleukins): Stimulate immune system activity, including inflammation.
  • Interferons: Inhibit RNA viral reproduction.
  • Cellular Barriers: Neutrophils, macrophages, dendritic cells, and natural killer (NK) cells.
  • Neutrophils: First responders to infection, short lifespan, link innate and acquired immunity. Concentrated in skin, lungs, and GI tracts.
  • Macrophages: Long-term phagocytosis, originate from monocytes.
  • Dendritic Cells: Link innate and acquired immunity.
  • Natural Killer (NK) Cells: Destroy cancer and infected cells.
  • Phagocytosis: Digestion of foreign particles by immune cells.
  • Inflammation Trigger: Release of cytokines by macrophages.
  • Inflammation Process (Edema): Vasodilation of capillary walls leads to fluid accumulation.
  • Fibrin Clot: Prevents spread of infection during inflammation.
  • Pyrogens: Substances that induce fever by acting on the hypothalamus.
  • Opsonization: Marking pathogens for phagocytosis.
  • Edema: Accumulation of fluid in tissues.
  • Cytokine Signaling (e.g. Paracrine, Autocrine): Paracrine signaling is secretion to nearby cells.
  • Acute-Phase Proteins (e.g., Ferritin, C-reactive protein): Bind and sequester iron.
  • Mannose-binding lectin: Activates complement cascade.
  • Serum amyloid A: acute phase protein
  • Transferrin: binds iron to inhibit pathogen growth
  • Bacteriocins: antimicrobial peptides secreted by microbiota

Adaptive Specific Host Defenses

Primary and Secondary Responses

  • Primary response: First exposure to a pathogen, features lower antibody concentration and initial antibody production (IgM appears first, followed by IgG).
  • Secondary response: Faster and more powerful response with larger antibody concentration, primarily dominated by IgG production.

Two Major Categories of Adaptive Immunity

Humoral Immunity

  • Antibody-mediated by B cells that remain in the bone marrow.
  • Targets pathogens in body fluids.
  • Effective against extracellular pathogens.

Cellular Immunity (Cell-Mediated)

  • Mediated by T cells that pass through the thymus.
  • Targets infected or abnormal cells (e.g., virus-infected cells, tumor cells).
  • Epitopes: Regions on antigens that B and T cells recognize.

Clonal Selection

  • Process activating B and T cells specific to an antigen.
  • Antigens bind to specific receptors on B/T cells.
  • Activated cells divide and differentiate into:
    • Effector cells: Target and eliminate pathogens.
    • Memory cells: Long-lived B/T cells; provide a faster, stronger response with subsequent exposures.

Antibody (Immunoglobulin) Structure

  • Basic Y-shaped structure, made of two heavy and two light chains joined by disulfide bonds.
  • Fab region: Antigen-binding site (highly variable), two arms of Y
  • Fc region: Binding site for complement system and phagocytic cells (trunk of Y)

Classes of Antibodies

  • IgM: First antibody produced; short-lived, indicates primary immune response, 10 binding sites.
  • IgG: Most abundant in circulation; crosses the placenta for fetal immunity, 2 binding sites.
  • IgA: Mucosal immunity (respiratory and GI tracts), e.g., saliva, tears, 4 binding sites.
  • IgE: Involved in allergic reactions, 2 binding sites.
  • IgD: Acts as a receptor on B cells, 2 binding sites.

Differences Between T Lymphocytes

  • Cytotoxic T Cells (CTLs): Eliminate infected or tumor cells (CD8 co-receptor).
  • Helper T Cells (TH): Regulate immune response, help produce antibodies.
    • TH1: Stimulates macrophages to destroy bacteria.
    • TH2: Promotes humoral immunity by aiding B cells.

Vaccine Types

  • Live, Attenuated Vaccines: Contain weakened microbes, strong response (e.g., Tuberculosis).
  • Inactivated Vaccines: Contain killed pathogens; require boosters (e.g., Cholera).
  • Subunit Vaccines: Contain antigen fragments; cannot cause disease (e.g., Hepatitis B).
  • Toxoid Vaccines: Contain inactivated toxins; require boosters (e.g., Tetanus).
  • Conjugate Vaccines: Combine weak antigens with strong ones to boost response (e.g., Haemophilus influenzae type b).

Mechanisms of Acquiring Immunity

Active Immunity

  • Body produces its own antibodies.
    • Natural: Infection.
    • Artificial: Vaccination.

Passive Immunity

  • Body receives antibodies.
    • Natural: Maternal antibodies via placenta or breast milk.
    • Artificial: Antibody injections.

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Explore the critical components of the innate immune system, including its functions and physical barriers. This quiz covers the roles of microbiota, mucosal membranes, and various immune molecules in protecting the body against pathogens. Test your knowledge on non-specific defenses crucial for immune response.

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