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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    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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