Lymphatic System: Functions, Tissues & Pathologies
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Questions and Answers

A patient is given an injection of antibodies produced by another individual who recovered from the same illness. What type of immunity is this an example of and why?

  • Active immunity; because the patient is exposed to a weakened form of the pathogen, stimulating a long-term immune response.
  • Passive immunity; because the patient is receiving pre-formed antibodies from an external source, providing immediate but temporary protection. (correct)
  • Active immunity; because the patient's own immune system is producing antibodies and the immune system develops immunological memory.
  • Innate immunity; because the response is non-specific and does not involve the adaptive immune system.

    • Which of the following cell types is capable of directly presenting antigens via MHC I?

  • Macrophages only
  • B cells only
  • All nucleated cells (correct)
  • Dendritic cells only

    • Which of the following best describes the role of professional antigen-presenting cells (APCs)?

  • Directly killing virus-infected cells without the need for T cell activation.
  • Presenting antigens on MHC II to activate helper T cells. (correct)
  • Activating cytotoxic T cells through MHC I presentation.
  • Secreting antibodies to neutralize pathogens in the bloodstream.

    • A researcher is investigating a new type of immune cell. Initial findings show the cell originates from a lymphoid progenitor and can directly kill infected cells. Which of the following cell types is MOST likely the subject of this research?

    <p>Natural Killer (NK) cell (D)</p> Signup and view all the answers

    What is the primary difference between leukocytes and lymphocytes?

    <p>Lymphocytes are a subset of leukocytes, all originating from a lymphoid progenitor. (B)</p> Signup and view all the answers

    During a viral infection, a cell displays viral antigens on its MHC I molecules. Which of the following immune cells is MOST likely to recognize and respond to this?

    <p>Cytotoxic T cell (CD8+) (C)</p> Signup and view all the answers

    A B cell has bound to an antigen and is presenting it on MHC II. What is the NEXT step required to activate this B cell fully?

    <p>Binding of a helper T cell to the MHC II complex. (C)</p> Signup and view all the answers

    How do Natural Killer (NK) cells recognize and kill infected or cancerous cells?

    <p>By releasing perforin and granzyme to induce apoptosis in target cells. (D)</p> Signup and view all the answers

    Which of the following is NOT a primary function of regulatory T cells?

    <p>Directly destroying pathogens via phagocytosis. (A)</p> Signup and view all the answers

    A patient exhibits elevated levels of neutrophils in a blood test. This most likely indicates which condition?

    <p>Acute inflammation. (B)</p> Signup and view all the answers

    Which characteristic distinguishes erythrocytes from granulocytes?

    <p>Presence of a nucleus. (D)</p> Signup and view all the answers

    What is the primary function of thrombocytes (platelets)?

    <p>Preventing bleeding by forming blood clots. (D)</p> Signup and view all the answers

    Which of the following cell types is directly involved in allergic and asthmatic responses?

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

    A researcher is studying the immune system and needs cells that can mount a faster and stronger response upon future exposure to an antigen. Which type of cells would be most suitable for this study?

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

    During an experiment, a researcher observes that certain immune cells are releasing toxic reactive oxygen species to kill bacteria. Which type of cells are most likely exhibiting this behavior?

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

    Which of the following cell types are anucleate?

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

    Which of the following is the primary function of plasma cells?

    <p>Producing high volumes of antibodies. (C)</p> Signup and view all the answers

    Memory B cells contribute to immunological memory by:

    <p>Mounting a faster and stronger immune response upon re-exposure to a specific antigen. (A)</p> Signup and view all the answers

    Helper T cells require which of the following interactions to become activated?

    <p>MHC II presentation on professional APCs along with a co-stimulatory signal. (B)</p> Signup and view all the answers

    What is the role of T cell cytokines released by effector helper T cells?

    <p>Causing B cell antibody class switching and enhanced cytotoxic T cell activation. (C)</p> Signup and view all the answers

    Cytotoxic T cells recognize antigens presented on which type of molecule?

    <p>MHC I molecules on infected or cancerous cells. (B)</p> Signup and view all the answers

    How do effector cytotoxic T cells kill target cells?

    <p>By releasing perforin and granzymes, which induce apoptosis. (C)</p> Signup and view all the answers

    If a patient lacks the ability to produce functional CD4+ T cells, which of the following immune responses would be most severely impaired?

    <p>The activation of B cells and subsequent antibody production. (C)</p> Signup and view all the answers

    Which feature distinguishes memory cytotoxic T cells from effector cytotoxic T cells?

    <p>Memory cells provide a quicker and stronger response upon subsequent exposure. (D)</p> Signup and view all the answers

    What cellular process contributes to the diversity of T-cell receptor (TCR) specificities?

    <p>Alternative splicing of introns in the genes coding for the TCR's variable region. (D)</p> Signup and view all the answers

    During T cell development in the thymus, a T cell receptor (TCR) interacts moderately with self-antigens. According to the selection processes, what type of T cell is MOST likely to result from this interaction?

    <p>A regulatory T cell. (A)</p> Signup and view all the answers

    A developing T cell in the thymus interacts strongly with MHC class I molecules. What is the MOST likely outcome for this T cell?

    <p>It will mature into a CD8+ cytotoxic T cell. (B)</p> Signup and view all the answers

    What is the PRIMARY mechanism by which antibodies facilitate the destruction of pathogens?

    <p>Enhancing phagocytosis and activating the complement system (opsonization). (B)</p> Signup and view all the answers

    An antibody's ability to bind to a specific antigen is primarily determined by what region of the antibody structure?

    <p>The variable (Fab) region. (B)</p> Signup and view all the answers

    A B cell initially secretes IgM antibodies. Upon activation by a helper T cell and exposure to specific cytokines (interleukins), it begins to secrete IgG antibodies instead. What process has occurred?

    <p>Class/isotype switching. (A)</p> Signup and view all the answers

    Which component of the immune system is composed of serum proteins that enhance other immune defenses?

    <p>The complement system. (A)</p> Signup and view all the answers

    A researcher is studying the function of different antibody isotypes during a parasitic infection. They observe that a particular antibody isotype is highly effective at activating mast cells and basophils to release inflammatory mediators. Which antibody isotype BEST corresponds to this function?

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

    Which of the following accurately describes the role of C3b in the complement system?

    <p>It opsonizes pathogens, enhancing phagocytosis by binding to CR1 on phagocytes. (A)</p> Signup and view all the answers

    How does the membrane attack complex (MAC) contribute to the complement system's function?

    <p>By forming pores in the pathogen's membrane, leading to cell lysis. (B)</p> Signup and view all the answers

    Interferons exert their antiviral effects through which of the following mechanisms?

    <p>Inducing apoptosis in infected cells and alerting neighboring cells to prepare for viral attack. (C)</p> Signup and view all the answers

    Which of the following is NOT a macroscopic sign of inflammation?

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

    Which of the following is the primary role of interferon-gamma in the interferon response?

    <p>Mobilizing macrophages and NK cells to phagocytose infected or cancerous cells. (B)</p> Signup and view all the answers

    Which of the following events initiates the inflammatory response?

    <p>Pathogen invasion, cellular damage, or irritant exposure. (B)</p> Signup and view all the answers

    What is the role of complement protein C3a in the immune response?

    <p>Promoting inflammation by increasing vascular permeability and attracting phagocytes. (B)</p> Signup and view all the answers

    Histamine release during inflammation directly contributes to which of the following macroscopic signs?

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

    Which of the following cell types is primarily responsible for mediating allergic responses through the release of histamine, leading to local blood vessel dilation?

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

    A patient presents with a suspected parasitic infection. An elevated count of which type of granulocyte would most likely support this diagnosis?

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

    Which of the following cell types functions as a professional antigen-presenting cell (APC) and is also involved in phagocytosing pathogens?

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

    Which of the following cells is a precursor to macrophages?

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

    Dendritic cells play a crucial role in initiating adaptive immune responses. How do they contribute to this process after encountering pathogens?

    <p>Migrating to lymph nodes to present antigens to T cells. (A)</p> Signup and view all the answers

    Which of the following represents a component of the adaptive immune system?

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

    Which of the following cell types is NOT involved in innate immunity?

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

    Which cell type utilizes granzyme and perforin to induce apoptosis in infected or cancerous cells?

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

    What is the primary function of platelets in the blood?

    <p>Forming blood clots (C)</p> Signup and view all the answers

    In the context of the immune system's lines of defense, which of the following exemplifies the first line of defense?

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

    Which of the following is a characteristic of the third line of defense in the immune system?

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

    Which cell type matures in the thymus and plays a critical role in activating B cells and killing infected cells?

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

    How do neutrophils contribute to the innate immune response against bacterial infections?

    <p>By phagocytosing and killing bacteria via oxidative burst. (B)</p> Signup and view all the answers

    Mast cells and basophils both release histamine, but what is a key difference in their location within the body?

    <p>Mast cells reside in tissues, while basophils circulate in the blood. (D)</p> Signup and view all the answers

    What role does the mucociliary escalator play as part of the immune system?

    <p>It is a physical barrier, trapping and removing pathogens from the respiratory tract. (B)</p> Signup and view all the answers

    Flashcards

    Passive Immunity

    Immunity gained from antibodies from another source, like breastfeeding or antibody injection.

    Antigen Presenting Cells (APCs)

    Cells that present antigens on MHC I to cytotoxic T cells; all cells are APCs.

    Professional APCs

    Cells that present antigens on MHC II to helper T cells; includes B cells, macrophages, dendritic cells.

    Leukocytes

    White blood cells involved in the immune response, including lymphoid and myeloid cells.

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    Lymphocytes

    Cells originating from common lymphoid progenitor; includes B cells, T cells, and NK cells.

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    Natural Killer (NK) Cells

    Cytotoxic lymphocytes that kill virus-infected or cancerous cells using perforin and granzyme.

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    B Cells

    Lymphocytes with antibodies; they bind antigens, present fragments on MHC II, and can differentiate into plasma and memory B cells.

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    Clonal Expansion

    Process where activated B cells proliferate and differentiate into plasma and memory B cells.

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    Plasma Cells

    B cells that produce large amounts of antibodies specific to the initial pathogen epitope.

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    Memory B Cells

    B cells that remember pathogens and can mount a quicker immune response upon re-exposure.

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    Helper T Cells (CD4+)

    Activated by APCs to help activate B cells and cytotoxic T cells through cytokine release.

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    Cytotoxic T Cells (CD8+)

    Activated T cells that kill infected or cancerous cells via specific binding.

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    E ector Helper T Cells

    Differentiated helper T cells that release cytokines to aid other immune responses.

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    Memory Cytotoxic T Cells

    Cytotoxic T cells that recognize antigens from prior infections, ready for future attacks.

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    Reserve Immune Cells

    Cells that respond faster and stronger in future immune responses.

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    Regulatory T Cells

    Suppressive T cells that regulate the immune response to prevent autoimmunity.

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    Myelocytes

    Cells originating from a myeloid progenitor, including blood components.

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    Erythrocytes

    Red blood cells that carry oxygen, lacking nuclei, not involved in immunity.

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    Thrombocytes

    Platelets formed from megakaryocytes, aid in blood clotting, anucleate cells.

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    Granulocytes

    Phagocytic cells with granules, involved in destroying antigens.

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    Neutrophils

    Most abundant leukocytes, first responders to inflammation, phagocytose bacteria.

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    Eosinophils

    Cells primarily involved in allergic and asthmatic responses.

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    TCR Variable Region

    The part of the T cell receptor that varies and recognizes specific antigens, created by alternative splicing.

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    Negative Selection

    The process in the thymus eliminating T cells with high self-reactivity to prevent autoimmunity.

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    Positive Selection

    The process that keeps T cells with low self-reactivity that can bind to MHC molecules.

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    Goldilocks Selection

    Selection of T cells that are just right in self-reactivity, leading to the formation of regulatory T cells.

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    Opsonization

    The process by which antibodies mark pathogens for destruction, aiding phagocytosis.

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    Antibody Structure

    Consists of heavy and light chains, with variable and constant regions, enabling antigen binding.

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    Class/Isotype Switching

    The process where activated B cells change their antibody class in response to signals from T cells.

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    Complement System

    A group of proteins that enhance the ability of antibodies and phagocytes to clear pathogens.

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    Complement Protein Functions

    The three major functions of complement proteins: opsonization, cytotoxicity, and inflammation.

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    Cytotoxicity

    Induces cell lysis via the membrane attack complex (MAC) to destroy infected cells.

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    Inflammation

    Response to pathogens or irritants marked by redness, swelling, heat, pain, and loss of function.

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    Interferons

    Antiviral cytokines that notify neighboring cells and recruit immune cells in response to infection.

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    Self Destruction in Immunity

    Interferons trigger apoptosis in infected cells to eliminate the virus.

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    Recruiting Phagocytes

    Interferon gamma mobilizes macrophages and NK cells to destroy infected or cancerous cells.

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    Histamine Release

    A molecule released by basophils during allergic reactions or pathogen invasion, causing inflammation.

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    Basophils

    White blood cells that release histamine and promote blood vessel dilation.

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    Mast Cells

    Similar to basophils but reside in tissues; they also release histamine.

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    Macrophages

    Phagocytic cells that destroy pathogens and present antigens to T cells.

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    Monocytes

    Precursors to macrophages; they kill bacteria through oxidative bursts.

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    Dendritic Cells

    Professional APCs that phagocytose pathogens and activate T cells.

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    First Line of Defence

    Physical barriers like skin and mucous membranes.

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    Second Line of Defence

    Innate immune response involving phagocytic cells and NK cells.

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    Third Line of Defence

    Adaptive immune system involving B and T cells; has memory.

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    Platelets

    Cell fragments for blood clotting; involved in the coagulation cascade.

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    Red Blood Cells

    Carry oxygen in the body using hemoglobin.

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    Study Notes

    Lymphatic System Functions

    • The lymphatic system is an open network, unlike the circulatory system.
    • It drains excess interstitial fluid (lymph) from capillary beds, preventing blood volume loss.
    • Lymph is returned to systemic circulation via the subclavian vein.
    • Valves in lymphatic tubules prevent backflow.
    • Lymph nodes contain immune cells (B and T cells) to mount an immune defense.
    • Lymph vessels called lacteals absorb fats from the small intestine.

    Lymphatic Tissue

    • Primary lymphatic tissue includes:
      • Thymus: T cell maturation site
      • Spleen: Filters blood, houses immune cells
      • Lymph nodes: Collect lymph, house immune cells
    • Secondary lymphatic tissue (MALT) is lymphoid tissue in various locations like tonsils, appendix, etc.

    Pathologies

    • Lymphedema: Swelling due to insufficient fluid drainage by the lymphatic system.

    Immune System Types

    • Components categorized as humoral (body fluids) or cell-mediated (leukocytes).
    • Innate immunity is non-specific and includes physical barriers, chemicals, and non-specific cells.
    • Adaptive immunity is specific and includes B and T cells.
    • Active immunity develops after exposure to an antigen, while passive immunity is acquired from another source.

    Cells of the Blood

    • Antigen-presenting cells (APCs) present antigens on MHC molecules to other immune cells.
    • Professional APCs include B cells, macrophages, and dendritic cells.

    Lymphocytes

    • A category of cells including B cells, T cells, and NK cells, originating from a common lymphoid progenitor.
    • Natural Killer (NK) cells destroy infected or cancerous cells.
    • B cells produce antibodies, mature in the bone marrow, and are professional APCs. Plasma cells produce antibodies. Memory B cells provide immunological memory.
    • T cells have T cell receptors (TCRs) and mature in the thymus. Helper T cells activate immune responses. Cytotoxic T cells kill infected or cancerous cells. Memory T cells provide immunological memory.

    Myelocytes

    • A category including red blood cells, platelets, granulocytes, and macrophages.
    • Erythrocytes (red blood cells) carry oxygen.
    • Thrombocytes (platelets) are involved in blood clotting.
    • Granulocytes (neutrophils, eosinophils, basophils) are phagocytic cells involved in immune response. Neutrophils are the most numerous leukocytes and are frequently the first responders to inflammation. Eosinophils are involved in allergic and asthmatic responses, and basophils release histamine.
    • Macrophages, monocytes (precursors) are phagocytic and professional APCs, while dendritic cells interact with external environment at tissues (skin, lungs, etc.)

    Immune System Defenses

    • Innate immunity involves physical barriers, non-specific cells, and chemical responses.
    • Adaptive immunity involves specific B and T cells and immunological memory.

    Interferon Response

    • Interferons are antiviral cytokines secreted by infected cells, triggering self-destruction, warning neighboring cells, and recruiting phagocytes.

    Inflammatory Response

    • The inflammatory response is a combination of events that occur in response to pathogen invasion, cellular damage or irritants. It involves macroscopic signs like redness, swelling, heat and loss of function, plus microscopic signs like histamine release, vasodilation, and phagocyte recruitment.

    Pathologies

    • Regulatory T cell pathologies include susceptibility to cancer or autoimmune disorders, depending on levels of T-cell regulation.
    • Acquired Immunodeficiency Syndrome (AIDS), Type I Diabetes, Rheumatoid Arthritis, Lupus, Inflammatory Bowel Disease, Hashimoto's Thyroiditis and Asthma are examples of autoimmune diseases.

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