Immunology I: Functions and Characteristics of the Immune System
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Questions and Answers

What is a major function of the immune system?

  • Recognition of foreign entities or damage (correct)
  • Maintenance of body temperature
  • Destruction of self-cells
  • Production of hormones

    • According to the clonal selection theory, what occurs in the adaptive immune system?

  • Random mutations in immune cells
  • Selection and proliferation of immune cells that recognize specific antigens (correct)
  • Activation of the innate immune system
  • Suppression of the immune response

    • What is the main function of lymphoid-derived leukocytes?

  • Recognition of self and tolerance
  • Cellular differentiation
  • Antibody production (correct)
  • Phagocytosis of foreign particles

    • What is the primary function of primary lymphoid organs?

    <p>Maturation of immune cells</p> Signup and view all the answers

    What is a key component of the immune system?

    <p>A wide diversity of cells derived from the bone marrow</p> Signup and view all the answers

    What is a characteristic of the immune response?

    <p>Specificity, memory, primary responses, and secondary responses</p> Signup and view all the answers

    What is a function of the immune system?

    <p>Detection of damaged tissue and facilitation of regeneration or repair</p> Signup and view all the answers

    What is a disorder related to the immune system?

    <p>Autoimmune disease</p> Signup and view all the answers

    How do innate immune cells and molecular effectors recognize their targets?

    <p>Through less specific recognition of a range of targets</p> Signup and view all the answers

    What happens to foreign molecules or cells that cannot be destroyed by the immune system?

    <p>They are isolated from the rest of the body</p> Signup and view all the answers

    What is the primary difference between innate and adaptive immunity?

    <p>Innate immunity is genetically hard-wired, while adaptive immunity is changeable</p> Signup and view all the answers

    What is the function of adaptive immunity?

    <p>To activate when innate defenses are breached</p> Signup and view all the answers

    How do adaptive immune cells and molecular effectors recognize their targets?

    <p>Through highly specific recognition of a particular target</p> Signup and view all the answers

    Which type of granulocyte is primarily involved in defense against parasites?

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

    What is the unique role of Mast Cells in the immune system?

    <p>Orchestration of hypersensitivity responses</p> Signup and view all the answers

    Which type of cell is responsible for killing cells that express foreign molecules?

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

    What is the primary function of Neutrophils in the innate immune system?

    <p>Phagocytosis and formation of pus</p> Signup and view all the answers

    Which type of cell lacks antigen-specific receptors and is important in the innate immune system?

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

    What is the function of Basophils in the immune system?

    <p>Protection of mucosal body surfaces and release of histamine</p> Signup and view all the answers

    Which of the following cells is not a type of granulocyte?

    <p>Dendritic Cells</p> Signup and view all the answers

    What is the term for a cell that responds to receptor binding by deactivation of the cell?

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

    Which of the following is a characteristic of the adaptive immune system?

    <p>Self/non-self discrimination</p> Signup and view all the answers

    What is the term for a group of effector T/B cells that express the same antigen receptor and are derived from the same parent cell?

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

    What is the primary function of dendritic cells in the immune system?

    <p>To present antigens to T cells</p> Signup and view all the answers

    What is the term for a cell that has not reached a point where it can become activated?

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

    Which of the following cells is responsible for orchestrating hypersensitivity responses?

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

    What is the term for a mature cell that has not yet been activated?

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

    What is the primary difference between innate and adaptive immune responses in terms of response time?

    <p>Innate responses take hours to days, while adaptive responses take days to weeks.</p> Signup and view all the answers

    Which of the following is a characteristic of both adaptive and innate immune responses?

    <p>Self-limiting</p> Signup and view all the answers

    What is the characteristic of fixed responses with repeated exposures to antigen in the innate immune response?

    <p>The response remains the same with repeated exposures.</p> Signup and view all the answers

    What is the primary mechanism of generating diversity in the adaptive immune response?

    <p>Randomly 'shuffling' portions of genes for lymphocyte receptors.</p> Signup and view all the answers

    What is the definition of an epitope?

    <p>The molecular entity that binds to the receptor.</p> Signup and view all the answers

    What is the characteristic of a hapten?

    <p>A substance that can bind to an antibody, but cannot generate an immune response.</p> Signup and view all the answers

    What is the clonal selection theory?

    <p>Each lymphocyte bears a single type of receptor with a unique specificity.</p> Signup and view all the answers

    What is the function of B cell receptors?

    <p>To recognize and bind to antigens, and to secrete antibodies into the blood.</p> Signup and view all the answers

    What is the characteristic of T cell receptors?

    <p>They are structurally very similar to the Fab portion of an antibody.</p> Signup and view all the answers

    What is the characteristic of memory in the adaptive immune response?

    <p>Exposure to an antigen increases the ability to respond to the same or closely related antigen following re-exposure.</p> Signup and view all the answers

    What is the characteristic of secondary immune responses?

    <p>They are faster and larger than primary immune responses.</p> Signup and view all the answers

    What is the primary function of the innate immunity?

    <p>To provide immediate, non-specific defense against infection</p> Signup and view all the answers

    How do cellular and molecular effectors of innate immunity recognize their targets?

    <p>Through less specific recognition of a range of targets</p> Signup and view all the answers

    What happens to foreign molecules or cells that cannot be destroyed by the immune system?

    <p>They are isolated from the rest of the body</p> Signup and view all the answers

    What is a characteristic of adaptive immunity?

    <p>It is highly specific and genetically 'changeable'</p> Signup and view all the answers

    What is the primary difference between innate and adaptive immunity?

    <p>Innate immunity is non-specific, adaptive immunity is specific</p> Signup and view all the answers

    What is the function of adaptive immunity?

    <p>To specifically recognize and respond to particular pathogens</p> Signup and view all the answers

    What is a primary function of Neutrophils?

    <p>Phagocytic and enter sites of infection</p> Signup and view all the answers

    What is a characteristic of Eosinophils?

    <p>Defense against parasites</p> Signup and view all the answers

    What is the primary function of Basophils?

    <p>Release histamine in hypersensitivity responses</p> Signup and view all the answers

    What is unique about Mast Cells?

    <p>Orchestrate hypersensitivity responses and reside in all connective tissues</p> Signup and view all the answers

    What is a characteristic of B cells?

    <p>Bone marrow derived and can differentiate into Ab-secreting plasma cells</p> Signup and view all the answers

    What is a characteristic of NK cells?

    <p>Lack antigen-specific receptors and kill infected cells</p> Signup and view all the answers

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

    <p>To present antigens to T cells</p> Signup and view all the answers

    What is the term for immunological unresponsiveness to self?

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

    Which of the following cells is long-lived and phagocytic?

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

    What is the characteristic of immune responses in both adaptive and innate immune systems?

    <p>Self-limiting</p> Signup and view all the answers

    What is the term for a cell that has not yet been activated, but has reached a point where it can become activated?

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

    Which of the following is a type of myeloid cell?

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

    What is the primary function of dendritic cells in the immune system?

    <p>To recognize and transport antigen to lymphoid organs</p> Signup and view all the answers

    What is the term for a group of effector cells that express the same antigen receptor and are derived from the same parent cell?

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

    What is the characteristic of a cell that responds to receptor binding by deactivation of the cell?

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

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

    <p>To orchestrate hypersensitivity responses</p> Signup and view all the answers

    What is the primary difference between the specificity of innate and adaptive immune responses?

    <p>Innate immune response recognizes patterns, while adaptive immune response recognizes specific entities</p> Signup and view all the answers

    What is the characteristic of the receptor binding in adaptive immunity?

    <p>The affinity of the receptor binding can increase with repeated exposures to antigen</p> Signup and view all the answers

    What is the mechanism of generating diversity in the adaptive immune response?

    <p>Random shuffling of gene portions for lymphocyte receptors</p> Signup and view all the answers

    What is the characteristic of a substance that can generate an adaptive immune response?

    <p>It can bind to a receptor and generate an immune response</p> Signup and view all the answers

    What is the characteristic of an epitope?

    <p>A molecular entity that can bind to a receptor</p> Signup and view all the answers

    What is the characteristic of a hapten?

    <p>A substance that can bind to a receptor but cannot generate an immune response</p> Signup and view all the answers

    What is the characteristic of the T-cell receptor?

    <p>It is never secreted and always stays attached to the membrane</p> Signup and view all the answers

    What is the characteristic of the secondary immune response?

    <p>It is faster and larger than the primary immune response</p> Signup and view all the answers

    What is the clonal selection theory?

    <p>The theory that each lymphocyte bears a single type of receptor with a unique specificity</p> Signup and view all the answers

    What is the characteristic of memory in the adaptive immune response?

    <p>The ability to respond to antigens more quickly and effectively upon re-exposure</p> Signup and view all the answers

    Which immune cells produce cytokines that inform helper T-cells about how to 'help' other immune cells?

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

    What is the primary function of primary lymphoid organs?

    <p>To generate and mature lymphocytes</p> Signup and view all the answers

    Which type of lymphoid tissue is responsible for bringing antigens and lymphocytes together?

    <p>Secondary lymphoid organs</p> Signup and view all the answers

    What is the purpose of Mucosa-associated lymphoid tissue (MALT)?

    <p>To collect Ag from mucosal surfaces</p> Signup and view all the answers

    What is the function of Peyer's Patches (PP) in the gut?

    <p>To collect Ag from epithelial surfaces of the GI tract</p> Signup and view all the answers

    What is the function of the spleen in the immune system?

    <p>To filter blood-borne antigens and destroy aged RBCs</p> Signup and view all the answers

    Which type of immune cell is dedicated to aiding only innate immune responses?

    <p>Certain subsets of helper T-cells</p> Signup and view all the answers

    What is the role of lymph nodes in the immune system?

    <p>To bring antigens and lymphocytes together</p> Signup and view all the answers

    What is the function of B-cells in the spleen?

    <p>To produce large quantities of antibodies and secrete them into the bloodstream</p> Signup and view all the answers

    Study Notes

    Immunology Overview

    • Immunology is a complex field that involves multiple functions, including protection from microbial pathogens, protection from foreign cells, detection of damaged tissue, and facilitation of regeneration or repair.
    • The immune system has many components, including cells derived from the bone marrow, lymphatic tissues, and molecular signals and effectors.
    • Immunology also deals with various disorders, such as allergy, autoimmune disease, acute and chronic inflammatory states, and bystander damage.

    Immune Response

    • The immune response involves recognizing foreign molecules, microbes, or cells, destroying them, and communicating between these two activities.
    • The immune system has two major functional divisions: innate immunity (the "1st line of defense") and adaptive immunity (activated when innate defenses are breached).
    • Innate immunity features cellular and molecular effectors that are less specific and genetically hard-wired, while adaptive immunity features highly specific and genetically changeable effectors.

    Adaptive vs. Innate Immune Response

    • Response time: Innate immunity responds within hours to days, while adaptive immunity responds within days to weeks.
    • Memory: Adaptive immunity has memory, while innate immunity does not.
    • Specificity: Adaptive immunity is highly specific, while innate immunity recognizes patterns.

    Specificity - Adaptive Immunity

    • Specificity involves recognition of a foreign molecule by high-affinity binding to a receptor.
    • Receptors are generated by genetic recombination and can increase in affinity over time.
    • Antigens are substances that can bind to a receptor, while immunogens are substances that can generate an adaptive immune response.
    • Epitopes are the molecular entities that bind to a receptor, and haptens are substances that can bind to an antibody but cannot generate an immune response.

    Hallmarks of Adaptive Immunity

    • Diversity: The vertebrate immune system can recognize ~10^16 distinct antigens through a diverse set of recognition molecules (receptors) on immune cells.
    • Clonal Selection Theory: Each lymphocyte bears a single type of receptor with a unique specificity, and receptor binding is required for cell activation.
    • Memory: Exposure to an antigen increases the ability to respond to the same or closely related antigen following re-exposure, resulting in faster, larger, and qualitatively different secondary immune responses.

    B Cell Receptor

    • Naïve B cells express Ab on their surface, which can be activated to secrete Abs into the blood.
    • B cell receptors have variable and constant regions, with the variable regions being "shuffled" and able to bind to antigen.
    • Antigens can be bound by many different antibodies, recognizing different epitopes.

    T Cell Receptor

    • T cell receptors are structurally similar to the Fab portion of an Ab, with two chains (alpha and beta) each having a variable and constant region.
    • T cell receptors are best at recognizing protein antigens and only recognize antigen through close communication with molecules on other cells (antigen presentation).
    • T cell receptors are never secreted and always stay attached to the membrane.

    Cells and Tissues of the Immune System

    • Myeloid cells include granulocytes (neutrophils, eosinophils, basophils), monocytes/macrophages, and dendritic cells.
    • Lymphoid cells include T cells, B cells, and NK cells.
    • Primary lymphoid tissue includes the bone marrow and thymus, while secondary lymphoid tissue includes lymph nodes, spleen, and lymphoid organs.

    Myeloid Progenitor Cells

    • Monocytes/macrophages are phagocytic, present antigens to T cells, and produce soluble messengers that help orchestrate immune responses.
    • Dendritic cells are resident in tissues, recognize infection, and transport antigens to lymphoid organs to present to T cells.
    • Granulocytes (neutrophils, eosinophils, basophils) are involved in defense against infection and play a role in hypersensitivity responses.
    • Mast cells reside in connective tissues, orchestrate hypersensitivity responses, and are important in mucosal immune responses.

    Immune Response Overview

    • The immune system has two major functional divisions: innate immunity and adaptive immunity.
    • Innate immunity is the "1st line of defense" and features cellular and molecular effectors that are:
      • Less specific, recognizing a range of targets
      • Genetically "hard-wired", with cells and molecular effectors that don't change during the lifespan of the organism
    • Adaptive immunity is activated when innate defenses are breached and features cellular and molecular effectors that are:
      • Highly specific, recognizing particular targets
      • Genetically "changeable", with cells and molecular effectors that change their germline DNA to produce unique receptors/effectors during the lifespan of the organism

    Characteristics of Innate and Adaptive Immune Responses

    • Response time: Innate immunity responds within hours to days, while adaptive immunity responds within days to weeks
    • Memory: Adaptive immunity has memory, whereas innate immunity does not
    • Specificity: Adaptive immunity is highly specific, recognizing particular targets, whereas innate immunity recognizes patterns
    • Diversity: Adaptive immunity has an extremely large number of entities that can be recognized and neutralized/destroyed, whereas innate immunity has a limited repertoire

    Adaptive Immunity

    • Specificity: Recognition of a foreign molecule by high-affinity binding to a receptor
    • Receptors are generated by genetic recombination (gene shuffling) of particular portions of the receptor
    • Antigens: Substances that can bind to a receptor of the adaptive immune system, including B-cell and T-cell receptors
    • Immunogens: Substances that can generate an adaptive immune response
    • Epitopes: The molecular entity that binds to the receptor, with different antibody affinities
    • Haptens: Substances that can bind to an antibody, but cannot generate an immune response

    Hallmarks of Adaptive Immunity

    • Diversity: The vertebrate immune system can recognize ~10^16 distinct antigens through randomly "shuffling" portions of genes for lymphocyte receptors and selecting receptors that are functional and do not recognize self
    • Specificity: Each lymphocyte bears a single type of receptor with a unique specificity, and receptor binding is required for cell activation
    • Clonal selection theory: Activated lymphocytes bear receptors of identical specificity as the parent cell, and those lymphocytes bearing receptors for self molecules are destroyed at an early stage

    B-Cell Receptors

    • Naïve B cells express Ab on their surface, where they are called B-cell receptors
    • Once activated, B cells secrete Abs into the blood (aka immunoglobulins – Igs)
    • B-cell receptors are composed of light chains and heavy chains, with variable and constant regions
    • Variable regions are the portions that are "shuffled" and that can bind to antigen
    • Some antigens can be bound by many different antibodies, recognizing different epitopes on the same antigen

    T-Cell Receptors

    • Structurally similar to the Fab portion of an Ab
    • Composed of two chains: alpha and beta, with variable and constant regions
    • Best at recognizing protein antigens
    • T-cell receptors are never secreted, always staying attached to the membrane
    • Recognize antigen by close communication with molecules on other cells, known as antigen presentation

    Memory

    • Exposure of the adaptive immune system to an antigen increases its ability to respond to the same or closely related antigen following re-exposure
    • Secondary immune responses are generally faster, larger, and qualitatively different, involving relatively high-affinity B-cell receptors
    • Memory can be explained by the clonal selection theory, where activated lymphocytes bear receptors of identical specificity as the parent cell

    Hallmarks of Adaptive and Innate Immunity

    • Self-limiting: Both adaptive and innate immune responses are transient, with tightly regulated and controlled immune responses
    • Self/non-self discrimination: The immune system must distinguish self from non-self, with immune responses to self resulting in autoimmunity, and immunological unresponsiveness to self being tolerance

    Cells and Tissues of the Immune System

    • Myeloid cells: Include granulocytes, monocytes, macrophages, and dendritic cells
    • Lymphoid cells: Include B cells, T cells, and natural killer cells
    • Primary lymphoid tissue: Includes bone marrow and thymus, where lymphocytes are generated and mature
    • Secondary lymphoid tissue: Includes lymph nodes, spleen, and MALT, where adaptive immune responses are initiated

    Primary Lymphoid Organs

    • Bone marrow: Where B cells and T cells are generated
    • Thymus: Where T cells mature

    Secondary Lymphoid Organs

    • Lymph nodes: Collect extracellular fluid and return it to the blood, with antigen-trapping and B/T cell interactions
    • Spleen: A "filter for blood" that collects blood-borne antigens, destroys aged RBCs, and produces large quantities of antibodies
    • MALT: Includes gut- and bronchial-associated lymphoid tissues, which collect Ag from mucosal surfaces and have specialized lymphoid tissue at the body's "wet" surfaces

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    Immunology I Introduction PDF

    Description

    This quiz covers the major functions and characteristics of the immune system, including recognition of foreign entities, destruction of pathogens, recognition of self and tolerance, specificity, and memory responses.

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