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Immunity Quiz: Innate and Adaptive Immunity
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Immunity Quiz: Innate and Adaptive Immunity

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Questions and Answers

Which characteristic distinguishes innate immunity from acquired immunity?

  • Innate immunity is present at birth. (correct)
  • Innate immunity requires previous exposure to antigens.
  • Innate immunity develops memory over time.
  • Innate immunity specifically targets pathogens.

    • What is a primary function of physiological barriers in innate immunity?

  • To prevent pathogen entry.
  • To directly kill invading microorganisms.
  • To produce antibodies.
  • To inhibit pathogen growth. (correct)

    • Which of the following factors does NOT influence innate immunity?

  • Previous infections. (correct)
  • Nutritional status.
  • Genetic factors.
  • Hormonal status.

    • What is the role of skin in innate immunity?

    <p>It acts as a physical barrier to prevent entry of microorganisms.</p> Signup and view all the answers

    Which division of antigens is categorized as self-antigens?

    <p>Autoantigens.</p> Signup and view all the answers

    Which of the following statements about innate immunity is false?

    <p>Innate immunity requires prior exposure to antigens.</p> Signup and view all the answers

    What type of barrier does mucus membrane represent in innate immunity?

    <p>Physical barrier.</p> Signup and view all the answers

    Which cells are primarily responsible for the immune response in the acquired immune system?

    <p>Lymphocytes.</p> Signup and view all the answers

    What distinguishes mononuclear phagocytes from polymorphonuclear granulocytes (PMNs)?

    <p>PMNs primarily consist of neutrophils.</p> Signup and view all the answers

    Which killing pathway of phagocytes relies on altering pH within the environment?

    <p>Oxygen independent microbicidal system</p> Signup and view all the answers

    What role do NK cells play in the immune response?

    <p>They participate in immune surveillance and kill tumor or virally infected cells.</p> Signup and view all the answers

    What characteristic is unique to Ab-dependent cytotoxic cells when targeting cells?

    <p>They utilize receptors that bind the FC portion of IgG for targeting.</p> Signup and view all the answers

    Which type of cells can contribute to resistance against fungal infections?

    <p>Both NK cells and macrophages</p> Signup and view all the answers

    What is a primary role of lysozyme in innate immunity?

    <p>Destroying the cell wall of bacteria</p> Signup and view all the answers

    Which of the following accurately describes Pathogen Associated Molecular Patterns (PAMPs)?

    <p>Structures common for certain groups of pathogens</p> Signup and view all the answers

    What initiates the process of phagocytosis in phagocytic cells?

    <p>Chemotaxis towards attracting molecules</p> Signup and view all the answers

    Which of the following statements is true regarding complement system in innate immunity?

    <p>It can directly kill and lyse some gram-negative bacteria</p> Signup and view all the answers

    What is the role of interferons (INF) in the immune response?

    <p>To provide an antiviral action during infections</p> Signup and view all the answers

    During phagocytosis, what occurs after formation of pseudopodia?

    <p>Formation of a phagosome</p> Signup and view all the answers

    Which component is involved in attracting phagocytic cells to sites of infection?

    <p>C5a and IL-8</p> Signup and view all the answers

    What defines the non-specific immune response primarily mediated by humoral factors?

    <p>Activation of complement and cytokines</p> Signup and view all the answers

    Natural Killer Cells (NKCs) arise from the same lineage as T-cells and B-cells.

    <p>False</p> Signup and view all the answers

    Polymorphonuclear granulocytes (PMNs) include both neutrophils and macrophages in their classification.

    <p>False</p> Signup and view all the answers

    The killing mode of lymphokine-activated killer cells (LAK cells) is primarily extracellular.

    <p>True</p> Signup and view all the answers

    The oxygen dependent microbicidal system of phagocytes is less toxic than the oxygen independent system.

    <p>False</p> Signup and view all the answers

    Antibody-dependent cellular cytotoxicity (ADCC) requires the participation of complement to kill target cells.

    <p>False</p> Signup and view all the answers

    Innate immunity is also referred to as specific immunity.

    <p>False</p> Signup and view all the answers

    Autoantigens are substances that originate from external sources.

    <p>False</p> Signup and view all the answers

    Barriers in innate immunity include factors such as skin and mucus membranes.

    <p>True</p> Signup and view all the answers

    Non-specific immune responses improve with repeated exposure to the same antigen.

    <p>False</p> Signup and view all the answers

    Lactic acid in fatty secretions plays a role in the mechanical barriers of innate immunity.

    <p>False</p> Signup and view all the answers

    Corticosteroids can influence the hormonal status affecting innate immunity.

    <p>True</p> Signup and view all the answers

    Innate immunity does not require previous exposure to an antigen.

    <p>True</p> Signup and view all the answers

    Sweat glands produce substances that encourage the growth of pathogenic organisms.

    <p>False</p> Signup and view all the answers

    Lysozyme has the capability to hydrolyze the protein layer of the cells of many fungi.

    <p>False</p> Signup and view all the answers

    Phagocytosis is a passive process that does not require enzymes.

    <p>False</p> Signup and view all the answers

    Complement activation leads to the generation of chemotactic factors such as C5a and C3a.

    <p>True</p> Signup and view all the answers

    Interferon gamma is secreted by macrophages after infection stimulation.

    <p>False</p> Signup and view all the answers

    Pathogen Associated Molecular Patterns (PAMPs) are structures unique to human cells.

    <p>False</p> Signup and view all the answers

    Cytokines play a crucial role in calling phagocytes to specific locations during an immune response.

    <p>True</p> Signup and view all the answers

    Lactoferrin and transferrin compete with bacteria for iron, thereby playing a role in innate immunity.

    <p>True</p> Signup and view all the answers

    The formation of phagolysosome occurs after the fusion of phagosome with mitochondria.

    <p>False</p> Signup and view all the answers

    Describe the primary distinction between the oxygen-dependent and oxygen-independent microbicidal systems of phagocytes.

    <p>The oxygen-dependent system utilizes toxic metabolites generated from oxygen, while the oxygen-independent system relies on enzymatic action and pH alteration.</p> Signup and view all the answers

    Explain the role of natural killer cells (NKCs) in the immune response.

    <p>NKCs are granular lymphocytes that perform immune surveillance, targeting tumor and virally infected cells without prior exposure.</p> Signup and view all the answers

    What is the function of antibodies in antibody-dependent cellular cytotoxicity (ADCC)?

    <p>Antibodies coat target cells and bind to Fc receptors on cytotoxic cells, facilitating their destruction without complement involvement.</p> Signup and view all the answers

    Identify the cells involved in the antibody-dependent cellular cytotoxicity (ADCC) mechanism.

    <p>The primary cells involved are NKCs, macrophages, and neutrophils.</p> Signup and view all the answers

    How do protective barriers contribute to the innate immune response?

    <p>Protective barriers, such as skin and mucous membranes, act as the first line of defense, preventing pathogen entry.</p> Signup and view all the answers

    How do phagocytes recognize Pathogen Associated Molecular Patterns (PAMPs)?

    <p>Phagocytes recognize PAMPs through specific receptors present on their cell surface that bind to these common structures of pathogens.</p> Signup and view all the answers

    Describe the role of cytokines in phagocytosis.

    <p>Cytokines direct the movement of phagocytes to sites of infection by acting as signaling molecules that indicate the presence of pathogens.</p> Signup and view all the answers

    What is the significance of nitrogen species in the phagolysosome during the process of phagocytosis?

    <p>Nitrogen species, such as free radicals, play a vital role in killing pathogens by causing oxidative damage within the phagolysosome.</p> Signup and view all the answers

    Explain the importance of chemotactic factors like C5a and IL-8 in innate immunity.

    <p>Chemotactic factors like C5a and IL-8 are essential in attracting phagocytic cells to the site of infection, enhancing the immune response.</p> Signup and view all the answers

    What is the function of the complement system in relation to non-specific immunity?

    <p>The complement system enhances the ability of antibodies and phagocytic cells to clear pathogens from an organism and promotes inflammation.</p> Signup and view all the answers

    How do lactoferrin and transferrin assist in the body's defense against bacterial infections?

    <p>Lactoferrin and transferrin bind iron, competing with bacteria for this essential nutrient, thereby inhibiting bacterial growth.</p> Signup and view all the answers

    Detail the steps involved in the phagocytosis process.

    <p>Phagocytosis involves: chemotaxis, attachment, formation of pseudopodia, phagosome formation, and fusion with lysosomes to form a phagolysosome.</p> Signup and view all the answers

    Identify the role of interferons in the immune response.

    <p>Interferons are proteins produced in response to viral infections that enhance the immune response and exhibit antiviral activity.</p> Signup and view all the answers

    What are the two main divisions of antigens recognized in innate immunity?

    <p>Foreign antigens (heteroantigens) and autoantigens (self-antigens).</p> Signup and view all the answers

    Identify one genetic factor that influences innate immunity.

    <p>Species level.</p> Signup and view all the answers

    Explain how physiological barriers contribute to innate immunity.

    <p>They include bactericidal substances like HCl in the stomach and lysozyme in tears, which inhibit pathogen growth.</p> Signup and view all the answers

    What characteristic of innate immunity indicates it is non-specific?

    <p>It is effective against a wide range of antigens.</p> Signup and view all the answers

    Describe the role of mechanical barriers in innate immunity.

    <p>Mechanical barriers, such as ciliary movement and sneezing, help physically expel pathogens from the body.</p> Signup and view all the answers

    What impact does hormonal status have on innate immunity?

    <p>Hormonal status, like the effects of corticosteroids, can suppress or enhance immune responses.</p> Signup and view all the answers

    How does the age of an individual influence innate immunity?

    <p>Innate immunity may weaken with age, especially in elderly individuals.</p> Signup and view all the answers

    What is a fundamental property that distinguishes innate immunity from acquired immunity regarding memory?

    <p>Innate immunity does not improve with repeated exposure to the same antigen.</p> Signup and view all the answers

    Lysozyme destroys the cell wall of bacteria by targeting ______.

    <p>peptidoglycans</p> Signup and view all the answers

    Phagocytic cells utilize ______ to engulf and destroy pathogens.

    <p>digestive enzymes</p> Signup and view all the answers

    The fusion of the phagosome with lysosomes forms the ______.

    <p>phagolysosome</p> Signup and view all the answers

    Cytokines are critical in attracting ______ to the site of infection.

    <p>phagocytes</p> Signup and view all the answers

    Interferon-alpha is secreted by ______ during viral infections.

    <p>macrophages</p> Signup and view all the answers

    The directed movement of a cell towards an attracting molecule is known as ______.

    <p>chemotaxis</p> Signup and view all the answers

    Lactoferrin and transferrin compete with bacteria for ______.

    <p>iron</p> Signup and view all the answers

    Pathogen Associated Molecular Patterns (PAMPs) are recognized by ______ on phagocytic cells.

    <p>cell receptors</p> Signup and view all the answers

    The two types of immunity are non-specific (innate) and ______ immunity.

    <p>specific</p> Signup and view all the answers

    Innate immunity provides the body's first line of defense against ______ and non-microbial agents.

    <p>microbial</p> Signup and view all the answers

    The absence of ______ immunity means that there is no improvement with repeated exposure to the same antigen.

    <p>memory</p> Signup and view all the answers

    Physical barriers, such as skin and mucous membranes, are part of the innate immune ______.

    <p>response</p> Signup and view all the answers

    Monocytes are found in the ______.

    <p>blood</p> Signup and view all the answers

    Neutrophils release granules and cytotoxic substances through an ______ killing pathway.

    <p>extracellular</p> Signup and view all the answers

    Autoantigens are categorized as ______-antigens.

    <p>self</p> Signup and view all the answers

    One example of a physiological barrier present in innate immunity is ______ substances like HCL in the stomach.

    <p>bactericidal</p> Signup and view all the answers

    Natural killer cells contribute 10-15% of lymphocytes in ______ blood.

    <p>peripheral</p> Signup and view all the answers

    The oxygen independent microbicidal system lowers ______ to kill pathogens.

    <p>pH</p> Signup and view all the answers

    Ciliary movement and sneezing are examples of ______ barriers that contribute to innate immunity.

    <p>mechanical</p> Signup and view all the answers

    Lymphokine-activated killer cells (LAK cells) are a type of ______ cell.

    <p>lymphocyte</p> Signup and view all the answers

    Genetic factors can influence innate immunity at the species, race, and ______ level.

    <p>individual</p> Signup and view all the answers

    Match the following types of phagocytic cells with their descriptions:

    <p>Monocytes = Found in the blood Macrophages = Found in tissues Neutrophils = Polymorphonuclear granulocytes Kupffer cells = Macrophages in the liver</p> Signup and view all the answers

    Match the following killing pathways of phagocytes with their characteristics:

    <p>Oxygen dependent = Metabolizes oxygen into toxic metabolites Oxygen independent = Utilizes pH alteration for microbicidal action Proteolytic enzymes = Type of enzyme involved in oxygen-independent killing Lactoferrin = Involved in iron competition with bacteria</p> Signup and view all the answers

    Match the following types of lymphocytic cells with their primary roles:

    <p>Natural Killer Cells (NKCs) = Cytotoxic against tumor and virally infected cells Antibody-dependent cytotoxic cells = Kill target cells coated with specific antibody Lymphokine-activated killer cells (LAK) = Activated by cytokines for enhanced cytotoxicity Granular lymphocytes = Contribute to immune surveillance</p> Signup and view all the answers

    Match the following components of the immune response with their actions:

    <p>Cytokines = Call phagocytes to specific locations IL-2 = Activates Natural Killer Cells ADCC = Involves membrane receptors for IgG Extracellular killing = Primary method of NKCs in targeting pathogens</p> Signup and view all the answers

    Match the following types of immune barriers with their functions:

    <p>Mechanical barriers = Prevent entry of pathogens Chemical barriers = Include substances like lactoferrin Biological barriers = Involve immune cells such as macrophages Cellular barriers = Include lymphocytes and phagocytes</p> Signup and view all the answers

    Match the following components with their respective functions in innate immunity:

    <p>Cytokines = Attract phagocytes to infection sites Lysozyme = Destroys bacterial cell walls Complement system = Enhances the ability to clear pathogens Interferon (INF) = Provides antiviral action</p> Signup and view all the answers

    Match the following immune cells with their primary roles:

    <p>Phagocytic cells = Engulf and ingest pathogens Natural Killer (NK) cells = Destroy infected or cancerous cells Dendritic cells = Present antigens to T-cells Macrophages = Participate in both phagocytosis and antigen presentation</p> Signup and view all the answers

    Match the following types of immune responses with their characteristics:

    <p>Humoral factors = Involve antibodies and complement Cellular factors = Involve direct attack by immune cells Non-specific immunity = Does not require prior exposure to pathogens Specific immunity = Recognizes and targets specific pathogens</p> Signup and view all the answers

    Match the following chemotactic factors with their sources:

    <p>C5a = Generated during complement activation IL-8 = Secreted by damaged cells C3a = Generated during complement activation Chemokines = Secreted by immune cells</p> Signup and view all the answers

    Match the following types of interferons with their origin:

    <p>INF-alpha = Secreted by macrophages INF-beta = Secreted by fibroblasts INF-gamma = Secreted by T-cells Type I interferons = Induced by viral infections</p> Signup and view all the answers

    Match the following steps of phagocytosis with their sequences:

    <p>Chemotaxis = Directed movement of phagocytes Attachment = Binding of phagocytes to pathogens Phagosome formation = Enclosing engulfed pathogens Phagolysosome fusion = Combining vesicles with lysosomes</p> Signup and view all the answers

    Match the following proteins with their roles in iron sequestration:

    <p>Lactoferrin = Found in milk and competes for iron Transferrin = Found in serum and binds to iron Hemoglobin = Carries oxygen and iron in blood Ferritin = Stores iron in a non-toxic form</p> Signup and view all the answers

    Match the following pathogen recognition structures with their types:

    <p>Lipopolysaccharides (LPS) = Bacterial cell wall component Peptidoglycan = Bacterial cell wall component dsRNA = Viral nucleic acid Chitin = Fungal cell wall component</p> Signup and view all the answers

    Match the following types of antigens with their descriptions:

    <p>Heteroantigens = Antigens that originate from outside the body Autoantigens = Antigens produced by the body itself Non-self antigens = Substances recognized as foreign by the immune system Superantigens = Antigens that cause an exaggerated immune response</p> Signup and view all the answers

    Match the following innate immunity components with their functions:

    <p>Skin = Serves as a physical barrier to pathogens Mucus membrane = Traps and expels pathogens Tears = Contain bactericidal substances like lysozyme Saliva = Washes away debris and microorganisms</p> Signup and view all the answers

    Match the following mechanisms of innate immunity with their types:

    <p>Physical barriers = Skin and mucus membranes that prevent pathogen entry Mechanical barriers = Sneezing and ciliary movement that expel pathogens Physiological barriers = Bactericidal substances in the stomach and tears Chemical barriers = Substances like sweat that inhibit pathogen growth</p> Signup and view all the answers

    Match the following characteristics of innate immunity with their descriptions:

    <p>Non-specific = Effective against a wide range of pathogens Natural = Present at birth and does not require exposure No memory = Response does not improve with repeated exposure Immediate response = Action occurs right after the pathogen is encountered</p> Signup and view all the answers

    Match the following determining factors of innate immunity with their types:

    <p>Genetic factors = Influences immunity based on species, race, and individual Age = Can weaken immune response in elderly individuals Hormonal status = Corticosteroids can impair immune function Nutritional status = Malnutrition can compromise the immune response</p> Signup and view all the answers

    Match the following types of innate immune responses with their definitions:

    <p>Inflammation = Localized response to injury or infection Phagocytosis = Process by which cells engulf and destroy pathogens Cytokine release = Signaling molecules that mediate immune response Complement activation = Enhances the ability to clear pathogens from an organism</p> Signup and view all the answers

    Match the following physiological barriers with their examples:

    <p>HCL in stomach = Destroys pathogens ingested with food Normal bacterial flora = Prevent pathogen colonization in the body Sweat = Contains salt that inhibits microbial growth Lysozyme in tears = Breaks down bacterial cell walls</p> Signup and view all the answers

    Match the following responses with their types in innate immunity:

    <p>Coughing = Mechanism to expel foreign particles from the respiratory tract Fever = Systemic response to infection that raises body temperature Inflammation = Isolates and removes infectious agents from the body Sneezing = Reflex action to clear the nasal passages of irritants</p> Signup and view all the answers

    Study Notes

    Immunity

    • Immunity (resistance): The body’s defense mechanisms against infectious diseases.
    • Two types of immunity:
      • Innate immunity: Natural, non-specific, present at birth.
      • Adaptive immunity: Specific, acquired, develops after exposure to a pathogen.

    Innate Immunity

    • Provides the body's first line of defense against infectious agents (microbial and non-microbial).
    • Does not require prior exposure and does not have memory.
    • Components react immediately to an invading organism or antigen.
    • Antigen: A substance that stimulates the immune response, specifically activating lymphocytes (white blood cells).
    • Two types of antigens are recognized:
      • Foreign antigens (heteroantigens): Non-self antigens.
      • Autoantigens (self-antigens) : Antigens present on the body's own cells.

    Characteristics of Innate Immunity

    • Non-specific: Effective against a wide range of antigens.
    • Natural: Present at birth.
    • No memory: Does not improve with repeated exposure to the same antigen.

    Determining Factors of Innate Immunity

    • Genetic factors:
      • Species level
      • Race level
      • Individual level
    • Age: Elderly individuals have weaker immune systems.
    • Hormonal status: Corticosteroids suppress immune function.
    • Nutritional status: Malnutrition weakens immune function.

    Mechanism of Innate Immunity

    • Barriers
      • Physical barriers:
        • Skin: The most important physical barrier.
        • Mucous membranes: Line the internal surfaces of the body.
      • Mechanical barriers:
        • Ciliary movement: Removal of mucus and debris (e.g. trachea).
        • Sneezing and coughing: Expel pathogens.
        • Washing action of bodily fluids: Tears, saliva and urine remove pathogens.
      • Physiological barriers:
        • Bactericidal substances: HCL in the stomach, lysozyme in tears.
        • Normal bacterial flora (commensal): Suppress growth of pathogenic organisms (e.g. Lactobacilli in the vagina).
        • Sweat glands: Salt inhibits growth of pathogens by drawing water from their cells.
        • Antimicrobial peptides
        • Lysozyme: Destroys bacteria by breaking down peptidoglycans in bacterial cell walls.
    • Cellular Factors:
      • Phagocytic cells: Engulf and destroy pathogens.
      • Natural Killer (NK) cells: Destroy abnormal or infected cells.
      • Dendritic cells: Present antigens to adaptive immune cells.
    • Humoral Factors:
      • Complement system: Proteins that help to destroy pathogens.
      • Cytokines: Signaling molecules produced by cells that modify the immune response.
      • Acute phase proteins: Produced by the liver in response to inflammation (e.g. C-reactive protein (CRP) & fibrinogen).

    Phagocytosis

    • An important feature of cellular innate immunity.
    • Phagocytic cells: Ingest and destroy pathogens or particles.
    • Phagocytes patrol the body for pathogens and are attracted to specific locations by cytokines.
    • Phagocytes perform the following steps in destroying pathogens:
      • Chemotaxis: Directed movement towards an attractant (e.g. C5a, IL-8).
      • Attachment to the organism
      • Formation of pseudopodia (arms) around the pathogen.
      • Fusion of pseudopodia and phagosome formation.
      • Fusion of phagosome with lysosomes, forming a phagolysosome that digests the pathogen.

    Phagocytic Cells

    • Two types of phagocytes:
      • Mononuclear phagocytes:
        • Monocytes: Found in the blood.
        • Macrophages: Found in the tissues (e.g. Kupffer cells in the liver, histiocytes in connective tissue).
      • Polymorphonuclear granulocytes (PMNs):
        • Neutrophils: Primary phagocytes and can also release granules and cytotoxic substances extracellularly.

    Killing Pathways of Phagocytes

    • Oxygen dependent microbicidal system
    • Oxygen independent microbicidal system.

    Lymphocytic cells

    • Certain lymphocytes contribute to nonspecific immune responses.
    • Examples:
      • Natural killer cells (NKCs): Granular lymphocytes that circulate in the body and recognize and destroy abnormal or infected cells (e.g. cancer cells, virally-infected cells).
        • Activated by IL-2.
        • Not T-cells or B-cells
        • Play a role in resistance to some bacterial, fungal, and parasitic infections.
        • Killing method: Extracellular killing.
      • Antibody-dependent cytotoxic cells (ADCC): Kill target cells coated with specific antibody.
        • Utilize the Fc portion of IgG to recognize the antibody.
        • Cells include: NKCs, macrophages, and neutrophils.
      • Lymphokine-activated killer cells (LAK cells): Can also be used in cancer immunotherapy.

    Protective Barriers of the body

    • The first line of defense against invading pathogens.
    • Prevent or retard the entry of cells and molecules into the body.

    Immunity

    • Immunity is the body's ability to resist infection and disease.
    • It is a complex system of defenses that protects against a wide range of harmful invaders, including bacteria, viruses, fungi, and parasites.

    Types Of Immunity

    • Innate Immunity: This is the body's first line of defense and is present from birth.
    • Acquired Immunity: This type of immunity develops after exposure to a specific pathogen, and is characterized by the ability to remember and mount a more rapid and effective response upon re-exposure.

    Innate Immunity

    • The innate immune system provides immediate protection against infection.
    • This system includes physical barriers, chemical defenses, and cellular components.
    • Characteristics:
      • Non-specific: It acts against a wide range of pathogens.
      • Natural: It is present from birth, without previous exposure.
      • No Memory: With repeated exposure, it does not improve its response.

    Factors Determining Innate Immunity

    • Genetics: Species, race, and individual genetic variations influence innate immunity.
    • Age: Eldery individuals may have a weakened immune system.
    • Hormonal Status: Corticosteroids can suppress the immune system.
    • Nutritional Status: Malnutrition can impair immune function.

    Mechanisms of Innate Immunity

    • Barriers: These prevent pathogens from entering the body:

      • Physical Barriers: Skin and mucous membranes are the first lines of defense.
      • Mechanical Barriers: Cilia, sneezing, coughing, tears, saliva, and urine help to remove pathogens.
      • Physiological Barriers:
        • Bactericidal Substances: Stomach acid and lysozyme in tears kill bacteria.
        • Normal Bacterial Flora: Commensal bacteria compete with pathogens for resources.
        • Sweat Glands: The salt in sweat inhibits pathogen growth.
        • Antimicrobial Peptides: These molecules directly kill pathogens.
        • Lysozyme: This enzyme destroys the cell walls of bacteria.

    • Cellular Factors: These recognize and destroy pathogens:

      • Phagocytic Cells: Monocytes (in blood), macrophages (in tissues), and neutrophils engulf and destroy pathogens.
      • Natural Killer (NK) Cells: These cells recognize and kill tumor cells and virus-infected cells.
      • Dendritic Cells: These cells capture and present antigens to adaptive immune cells.

    • Humoral Factors: These contribute to the immune response:

      • Complement System: This group of proteins works with antibodies to lyse pathogens.
      • Cytokines: These signaling molecules regulate immune responses.
      • Acute Phase Proteins: C-Reactive Protein (CRP) and fibrinogen are produced in response to inflammation.
      • Interferons (IFNs): These proteins are produced during viral infections to inhibit viral replication.
      • Lactoferrin & Transferrin: These proteins bind iron, preventing it from being used by bacteria.
      • Lysozyme: This enzyme hydrolyzes the cell walls of bacteria.

    Phagocytosis

    • Steps in Phagocytosis:
      • Chemotaxis: Phagocytes are attracted to the site of infection by chemical signals.
      • Attachment: Phagocytes attach to the pathogen.
      • Pseudopodia Formation: The phagocyte extends protrusions to engulf the pathogen.
      • Phagosome Formation: The pathogen is enclosed within a membrane-bound vesicle called a phagosome.
      • Phagolysosome Formation: The phagosome fuses with a lysosome, releasing enzymes that destroy the pathogen.

    Lymphocytic Cells

    • Natural Killer (NK) Cells: These cells are cytotoxic lymphocytes that kill virally infected cells and tumor cells.
    • Antibody-Dependent Cytotoxic Cells: These cells kill target cells coated with antibodies.
    • Lymphokine-Activated Killer (LAK) Cells: These cells are activated by cytokines and kill target cells.

    Protective Barriers

    • Physical Barriers: Skin, mucous membranes, and cilia are essential for preventing pathogen entry.

    Immunity

    • The body's natural defense mechanisms against infections
    • Two types: innate and adaptive immunity

    Innate Immunity

    • The body's first line of defense
    • Does not require prior exposure to pathogens
    • It recognizes and responds to a broad range of pathogens
    • No memory, meaning repeated exposure does not lead to improved response

    Characteristics of Innate Immunity

    • Non-specific: Works against a wide range of antigens
    • Natural: Present at birth
    • No Memory: Does not improve with repeated exposure to the same antigen.

    Factors Affecting Innate Immunity

    • Genetic: Species, race, and individual level variation
    • Age: Elderly individuals are more susceptible to infections
    • Hormonal status: Corticosteroids can suppress immunity
    • Nutritional status: Malnutrition weakens the immune system

    Mechanisms of Innate Immunity

    • Barriers: Prevent pathogens from entering the body
      • Physical barriers: Skin, mucus membranes
      • Mechanical barriers: Ciliary movement, sneezing, coughing, washing action of body fluids (tears, saliva, urine)
      • Physiological barriers: Bactericidal substances (HCl in stomach, lysozyme in tears), normal gut bacteria, sweat glands, antimicrobial peptides, lysozyme
    • Cellular Factors: Phagocytic cells (monocytes, macrophages, neutrophils), NK cells, dendritic cells
      • Recognize Pathogen Associated Molecular Patterns (PAMPs)
        • Structures common to pathogens, essential for their survival, replication, infectivity
        • Not present on human cells (ex: bacterial cell wall, viral nucleic acids)
    • Humoral Factors: Contribute to the non-specific immune response
      • Complement system: A group of proteins that can lyse bacteria and activate other immune cells.
      • Cytokines: Signaling molecules that coordinate immune responses
      • Acute phase proteins: Proteins produced in response to inflammation (ex: C-Reactive Protein (CRP) and fibrinogen)

    Phagocytosis

    • Process by which phagocytic cells engulf and destroy pathogens
    • Steps:
      • Chemotaxis: Movement of phagocytes towards chemoattractant molecules (C5a, IL-8)
      • Attachment: Binding of the phagocyte to the pathogen
      • Formation of Pseudopodia: Extensions of the phagocyte's cytoplasm that engulf the pathogen
      • Phagosome Formation: Formation of a vesicle containing the pathogen
      • Phagolysosome Formation: Fusion of the phagosome with a lysosome, releasing digestive enzymes that destroy the pathogen
    • Phagocytic Cells:
      • Mononuclear Phagocytes: Monocytes in blood, macrophages in tissues (Kupffer cells in liver, Histiocytes in connective tissue)
      • Polymorphonuclear Granulocytes (PMNs): Neutrophils

    Killing Pathways of Phagocytes

    • Oxygen-dependent Microbicidal System: Metabolism of oxygen into toxic metabolites that kill pathogens
    • Oxygen-Independent Microbicidal System: Lowering pH, releasing proteolytic and hydrolytic enzymes

    Lymphocytic Cells in Innate Immunity

    • Natural Killer Cells (NKC): Granular lymphocytes that perform immune surveillance and kill tumor cells and virally infected cells
      • Activated by IL-2
      • Lineage distinct from T and B cells
      • Kill target cells extracellularly
    • Antibody-dependent Cytotoxic Cells (ADCC): Kill target cells coated with specific antibody using FC receptors on their surface
    • Lymphokine-activated Killer Cells (LAK cells): Activated by cytokines (lymphokines)

    Protective Barriers

    • The body's first line of defense
    • Prevent or delay the entry of pathogens into the body

    Immunity

    • Immunity is the body's defense against pathogens.
    • There are two types of immunity: Innate and Adaptive.

    Innate Immunity

    • Innate immunity is the body's first line of defense.
    • Present at birth and doesn't require prior exposure to pathogens.
    • Doesn't improve with repeated exposure to the same pathogen.
    • Components:
      • Barriers: Physical (skin, mucous membranes), mechanical (cilia, coughing, sneezing), physiological (bactericidal substances like stomach acid, normal flora, sweat).
      • Cellular factors: Phagocytic cells, NK cells, dendritic cells.
      • Humoral factors: Complement system, cytokines, acute phase proteins like C-reactive protein (CRP) and fibrinogen.

    Determining Factors of Innate Immunity

    • Genetic factors: Species, race, individual variation
    • Age: Elderly individuals have weaker immunity
    • Hormonal status: Corticosteroids can suppress immune responses
    • Nutritional status: Malnutrition weakens the immune system

    Mechanism of Innate Immunity

    • Barriers: prevent pathogens from entering the body.
    • Cellular factors:
      • Phagocytic cells: engulf and destroy pathogens.
        • Monocytes: in the blood
        • Macrophages: in tissues (e.g. Kupffer cells in the liver, histiocytes in connective tissue).
        • Polymorphonuclear granulocytes (PMNs): Neutrophils can release cytotoxic substances extracellularly
      • NK cells: cytotoxic lymphocytes that attack tumor cells and virally infected cells.
    • Humoral factors:
      • Complement system: proteins that lyse bacteria.
      • Cytokines: signaling molecules that regulate immune responses.
      • Acute phase proteins: like CRP, produced in response to inflammation.

    Phagocytosis

    • Phagocytosis: process of engulfing and ingesting pathogens or particles.
    • Steps:
      • Chemotaxis: Movement of phagocytes towards the pathogen.
      • Attachment: Phagocyte binds to the pathogen.
      • Formation of pseudopodia: Phagocyte creates projections that surround the pathogen.
      • Fusion of pseudopodia and phagosome formation.
      • Fusion of phagosome with lysosomes: forms phagolysosome, where digestive enzymes destroy the pathogen.
    • Killing pathways:
      • Oxygen-dependent: uses toxic metabolites to kill bacteria.
      • Oxygen-independent: uses enzymes (proteolytic and hydrolytic), changes in pH, and other mechanisms to destroy pathogens.

    Lymphocytic Cells

    • Lymphocytes: contribute to non-specific immunity.
      • Natural Killer Cells (NK cells): granular lymphocyte that kill cells without prior exposure.
      • Antibody-dependent cytotoxic cells (ADCC): kill cells coated with antibodies.
      • Lymphokine-activated killer cells (LAK cells): activated by cytokines to eliminate infected cells.

    Protective Barriers of the Body

    • Barriers are the first line of defense.
    • They prevent or delay the entry of pathogens into the body.

    Immunity

    • Immunity refers to the protective mechanisms preventing infections
    • Two types of immunity: innate and acquired

    Innate Immunity

    • Non-specific, first line of defense against microbes and non-microbial agents
    • Present at birth, no memory
    • Doesn't improve with repeated exposure to the same antigen

    Determining Factors of Innate Immunity

    • Genetic factors: species, race, and individual level
    • Age: elderly individuals may have weakened immunity
    • Hormonal status: corticosteroids can suppress the immune system
    • Nutritional status: malnutrition weakens immunity

    Mechanisms of Innate Immunity:

    • Barriers: prevent entry of microorganisms into the body
      • Physical:
        • Skin: the most important barrier, contains lactic acid
        • Mucous membranes: covering internal surfaces, prevents attachment of organisms
      • Mechanical:
        • Ciliary movement, sneezing, coughing
        • Washing action: tears, saliva, urine
      • Physiological:
        • Bactericidal substances: HCl in the stomach, lysozyme in tears.
        • Normal bacterial flora (commensal): Lactobacilli in the vagina suppress the growth of pathogens
        • Sweat glands: salt inhibits pathogen growth
        • Antimicrobial peptides
        • Lysozyme: destroys bacterial cell walls
    • Cellular Factors:
      • Recognize Pathogen Associated Molecular Patterns (PAMPs)
        • PAMPs are structures common to certain pathogens
        • Not present on human cells
        • Examples: bacterial cell wall structures (LPS, peptidoglycans)
    • Humoral Factors:
      • Complement system
      • Cytokines
      • Acute phase protein = C-Reactive Protein (CRP), fibrinogen

    Phagocytosis

    • Important part of cellular innate immunity
    • Performed by phagocytic cells: engulf and kill pathogens
    • Phagocytes patrol the body and are called to specific locations by cytokines
    • Pathogens are killed by digestive enzymes or a respiratory burst
    • Steps:
      • Chemotaxis: movement towards attracting molecules
      • Attachment to the organism
      • Formation of pseudopodia
      • Fusion of pseudopodia to form a phagosome
      • Fusion of phagosome with lysosomes to form a phagolysosome

    Phagocytic Cells:

    • Mononuclear phagocytes
      • Monocytes in blood
      • Macrophages in tissues (e.g., Kupffer cells in the liver)
    • Polymorphonuclear granulocytes (PMNs)
      • Neutrophils release granules and cytotoxic substances extracellularly

    Killing Pathway of Phagocytes:

    • Oxygen-dependent microbicidal system: metabolize oxygen into toxic metabolites
    • Oxygen-independent microbicidal system: lowers pH, uses proteolytic and hydrolytic enzymes

    Lymphocytic Cells:

    • Certain lymphocytes are cytotoxic in the absence of prior exposure to the target
      • Natural Killer cells (NKCs):
        • Granular lymphocytes that function in immune surveillance
        • Naturally occurring cytotoxic lymphocytes activated by IL-2
        • Arise from bone marrow
        • Toxic to tumor and virally infected cells
        • Mode of killing is extracellular
      • Antibody-dependent cytotoxic cells:
        • Kill target cells coated with antibodies
        • Cells involved in antibody-dependent cellular cytotoxicity (ADCC) have an FC receptor
        • Types: NKCs, macrophages, neutrophils
      • Lymphokine-activated killer cells (LAK cells):
        • Activated by cytokines

    Protective Barriers of the Body

    • Represent the first line of defense
    • Prevent or retard entry of cells and molecules into the body

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    Description

    Test your knowledge on the immune system, focusing on innate and adaptive immunity. Explore key concepts such as types of immunity, the role of antigens, and characteristics of the body's defense mechanisms. This quiz will help reinforce your understanding of how the body fights infections.

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