Introduction to Immunology
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Questions and Answers

What is the definition of immunology?

The study of the immune system and its functions.

What are the components of the immune system?

White blood cells, antibodies, cytokines, and bone marrow.

Which of the following describe non-specific (innate) immunity? (Select all that apply)

  • Memory formation for future infections
  • Includes physical barriers like skin (correct)
  • Immediate response to pathogens (correct)
  • Specific recognition of antigens

    • Which type of immune system involves specific recognition of pathogens?

    <p>Adaptive (acquired) immunity</p> Signup and view all the answers

    Name a type of cell that plays a role in the adaptive immune system.

    <p>T cells or B cells.</p> Signup and view all the answers

    What is the role of antibodies?

    <p>To identify and neutralize pathogens such as bacteria and viruses.</p> Signup and view all the answers

    Phagocytes eat up pathogens in a process called ______.

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

    Cytokines are proteins that only slow down the immune response.

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

    Match the following terms with their meanings:

    <p>Antigen = Substance that triggers an immune response Cytokine = Protein that affects immune cell functions Phagocyte = Cell that engulfs pathogens Opsonin = Substance that marks pathogens for phagocytosis</p> Signup and view all the answers

    What cells are known as PMNs?

    <p>Polymorphonuclear leukocytes.</p> Signup and view all the answers

    Which type of lymphocyte matures in the bone marrow?

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

    Innate immunity is antigen-dependent.

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

    What is the main function of T Helper cells?

    <p>To mediate immune responses and help B cells respond to antigens.</p> Signup and view all the answers

    The primary function of __________ is to kill virus-infected and tumor cells.

    <p>Cytotoxic T cells</p> Signup and view all the answers

    What characterizes adaptive immunity?

    <p>Memory and specificity</p> Signup and view all the answers

    Name an anatomical barrier of the innate immune system.

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

    What is the mechanism of low pH in the stomach?

    <p>It kills most undigested pathogens.</p> Signup and view all the answers

    Which of the following is not a physiological barrier of the innate immune system?

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

    Describe the role of lysozyme in the immune system.

    <p>It cleaves bacterial cell walls.</p> Signup and view all the answers

    Match the type of immune response to its characteristic:

    <p>Innate immunity = Non-specific and immediate Adaptive immunity = Specific and has memory</p> Signup and view all the answers

    Study Notes

    Introduction to Immunology

    • Immunology is the study of the immune system, its components, and how it protects the body from disease
    • The immune system is a complex network of cells and organs that work together to defend against infection
    • There are two main branches to the immune system:
      • Innate immune system: a non-specific defense mechanism that provides an immediate, first line of defense
      • Adaptive immune system: A specific and highly targeted defense mechanism that remembers pathogens and can mount a stronger immune response upon re-exposure

    Natural Defence Systems of the Body

    • The skin, the largest organ of the body, provides a physical barrier against infection
    • Mucous membranes, found in the respiratory, gastrointestinal, reproductive, and urinary tracts, secrete mucus which traps microorganisms

    Immune System Components

    • Organ systems: The primary lymphoid organs (bone marrow and thymus gland) are involved in the production and maturation of immune cells
      • Secondary lymphoid organs: (lymph nodes, spleen, tonsils, adenoids, and Peyer's patches) provide a site for immune cell interactions and the initiation of an immune response

    Innate Immune System

    • The innate immune system provides a non-specific first line of defense against infection
    • Cells of the innate immune system:
      • Neutrophils: Phagocytic cells that kill bacteria and fungi. Most abundant WBC in circulation
      • Macrophages: Phagocytic cells that engulf and destroy pathogens, activate other immune cells, and play a role in tissue repair
      • Eosinophils: Kill parasites, involved in allergic reactions
      • Basophils: Involved in allergic reactions
      • Mast cells: Release histamine, heparin, and other inflammatory mediators in allergic and inflammatory responses
      • Dendritic cells: Capture and process antigens and present them to T cells to initiate an adaptive immune response

    Adaptive Immune System

    • The adaptive immune system is a specific and highly targeted defense mechanism. It is able to recognize and remember specific pathogens; It is slower to act than the innate immune system
    • Cells of the adaptive immune system:
      • T cells:
        • Helper T cells (Th cells) activate macrophages and B cells
        • Cytotoxic T cells kill infected cells
      • B cells: Produce antibodies

    Key Terminology

    • Antigen: A substance capable of eliciting an immune response
    • Antibody: A protein produced by B cells that binds to antigens and helps to neutralize pathogens
    • Cytokine: A chemical messenger that plays a role in immune cell communication and function
    • Opsonins: Antibodies or complement components that act as markers to help phagocytes identify and engulf pathogens
    • Phagocytosis: The process by which phagocytes engulf and destroy pathogens
    • Complement system: A group of proteins that work together to kill bacteria and activate other immune cells

    Comparing and Contrasting Innate and Adaptive Immunity

    • Innate immunity: Non-specific, rapid, first line of defense, no memory, includes:

      • Physical barriers (skin, mucous membranes, and cilia)
      • Chemical barriers (lysozyme, stomach acid, and antimicrobial peptides)
      • Cellular components (phagocytes, natural killer cells, and mast cells)

    • Adaptive immunity: Specific, slower to act, has memory, includes:

      • humoral immunity (antibody production by B cells)
      • cell-mediated immunity (elimination of infected cells by cytotoxic T cells)### Innate Immunity vs Adaptive Immunity

    • Innate immunity is non-specific and immediate, acting within hours. While adaptive immunity is specific and takes days or weeks to develop.

    • Innate immunity is non-antigen dependent, meaning it doesn't rely on prior exposure to pathogens. Adaptive immunity is antigen dependent, requiring exposure to a specific antigen.

    • Innate immunity lacks memory, meaning it doesn't remember past encounters with pathogens. Adaptive immunity has memory, allowing for a more rapid and robust response upon re-exposure to the same pathogen.

    Barriers of Innate Immune System

    • Anatomic barriers:

      • Skin: Acts as an initial mechanical barrier, preventing the entry of pathogens.
      • Mucous membrane: Normal flora compete with microbes for attachment sites, and mucous traps foreign microbes.
        • Examples: Nasal passages, respiratory tract, oral cavity.
      • Cilia: Propel microbes out of the body.
        • Located in the respiratory tract.

    • Physiological barriers:

      • Temperature (Fever): Elevated body temperature inhibits pathogen proliferation.
      • Low pH: Acidic pH kills most undigested pathogens.
        • Example: Stomach, due to the presence of hydrochloric acid.
      • Chemical mediators:
        • Lysozyme: Found in tears and saliva, cleaves (disrupts) the bacterial cell wall.
        • Interferon: Induces antiviral defenses in uninfected cells.
        • Complement: Lyses pathogens or facilitates phagocytosis.

    • Phagocytic/Endocytic Barriers:

      • Cells like macrophages, dendritic cells, and neutrophils engulf and kill microbes, breaking down foreign macromolecules, and digesting whole organisms.

    • Inflammatory Recruitment:

      • Tissue damage or infection triggers vascular fluid leakage, containing serum proteins with antibacterial activity. This attracts phagocytic cells to the site of infection.
      • Histamine and cytokines like chemokines are released at the infection site, enhancing the inflammatory response.

    Oral Cavity Barriers

    • The oral cavity harbors a diverse microbial community with many interacting species, including bacteria, fungi, and viruses.
    • Mucous membranes: Mucous helps trap and remove microbes.
    • Saliva: Contains lysozyme and histatine, which are antimicrobial peptides that kill bacteria.

    Lymphocytes (B cells)

    • B cells are a type of mononuclear leukocyte belonging to the adaptive immune system.
    • They mature in the bone marrow.
    • They differentiate into:
      • Plasma cells: Antibody-secreting cells responsible for the humoral/antibody-mediated response.
      • Memory cells: Remember past encounters with antigens, allowing for a faster and more effective response upon re-exposure.
    • T cells assist B cells in responding to antigens.

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    Description

    This quiz covers the basic principles of immunology, focusing on the immune system, its components, and its role in protecting the body from disease. Explore the differences between innate and adaptive immune responses and understand the natural defense systems of the body, including the skin and mucous membranes.

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