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Questions and Answers
What role does interleukin-2 play in the activation of helper T cells?
How do helper T cells assist in the activation of B cells?
Which component is responsible for the binding of helper T cells to macrophages during costimulation?
What happens to daughter helper T cells after they are stimulated by the same antigen?
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What is the sequence of events that occurs after an antigen is processed for helper T cell activation?
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What types of immune responses can lymphocytes give rise to?
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Which class of immunoglobulin is responsible for Rh reactions?
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What is the role of plasma cells in antibody production?
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What characterizes the primary immune response?
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Which of the following classes of immunoglobulin is mainly found in secretions like saliva and tears?
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What does the variable region of an antibody do?
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What percentage of serum immunoglobulins does IgE constitute?
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Which of the following best describes the secondary immune response?
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What is the primary function of cytotoxic T cells?
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Which type of T cell helps in the activation of cytotoxic T cells?
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How is naturally acquired active immunity obtained?
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What role do regulatory T cells play in the immune response?
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What is the first step in the activation of a cytotoxic T cell?
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Which of the following describes passive immunity?
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What initiates the proliferation of cytotoxic T cells?
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Which of the following is a characteristic of cytotoxic T lymphocytes?
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What is one of the primary functions of the lymphatic system?
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Which duct is responsible for draining lymph from the right upper limb and right side of the head and neck?
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Which component of the lymphatic system is primarily responsible for filtering lymph?
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What type of immunity is present at birth and provides generalized defense against pathogens?
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Which lymphatic organ serves as a blood reservoir and filters blood?
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What is the role of macrophages in the lymphatic system?
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What is contained in lymphatic capillaries that is essential for their function?
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What role do tonsils play in the lymphatic system?
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Which chemical mediator found in saliva and tears helps kill bacteria?
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At what age does the thymus gland stop growing?
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What is the primary function of Eosinophils?
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Which type of immunity is characterized by specific recognition of antigens and has memory?
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What type of white blood cell is primarily involved in antibody-mediated immunity?
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Where do T Cells mature?
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What is the role of the Major Histocompatibility Complex (MHC) molecule?
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What type of cytokine is released by macrophages to stimulate helper T cells?
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Which type of T Cell is responsible for activating macrophages and helping B cells?
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What is a self-antigen?
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What occurs during the proliferation of helper T cells?
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What are lymphocytes primarily involved in?
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Study Notes
Functions of the Lymphatic System
- Transports fluids, fats, and immune cells
- Helps maintain fluid balance in the body
- Absorbs fats from the small intestine
- Defends the body against infection
Lymphatic Drainage
- Right Lymphatic Duct: Drains lymph from the right upper limb, right head, neck, and chest and empties into the right subclavian vein
- Thoracic Duct: Drains lymph from the rest of the body and empties into the left subclavian vein
Components of the Lymphatic System
- Lymph: Fluid that circulates in lymphatic vessels, originates from blood plasma
- Lymphatic Vessels: Carry lymph throughout the body
- Lymph Nodes: Filter lymph and contain lymphocytes
- Tonsils: Lymphatic tissue in the throat that traps pathogens, three types: Palatine, Pharyngeal, and Lingual
- Spleen: Largest lymphatic organ, filters blood, stores white blood cells, and removes old red blood cells
- Thymus Gland: Located in the mediastinum, produces and matures T cells
Lymphatic Capillaries
- Tiny, closed-ended vessels that collect excess fluid from tissues
- Allow fluid to easily enter but not leave due to overlapping cells
- Join to form lymphatic vessels
### Lymph Formation and Movement
- Fluid from blood plasma in blood capillaries enters tissue spaces
- Lymphatic capillaries collect excess fluid in tissues, this becomes lymph
- Valves prevent lymph from flowing backward
- Lymph moves towards the heart due to muscle contractions
- Eventually returns to the blood circulation via the subclavian veins
Lymphatic Organs
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Tonsils:
- Palatine Tonsils: Located on each side of the oral cavity
- Pharyngeal Tonsils: Located near the internal opening of the nasal cavity (adenoid)
- Lingual Tonsils: Located on the posterior surface of the tongue
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Lymph Nodes:
- Bean-shaped structures that filter lymph
- Located in clusters throughout the body, particularly in the groin, armpit, and neck
- Lymph passes through lymph nodes before entering blood
- Contain macrophages and lymphocytes
- Immune cells are activated if foreign substances are detected
-
Spleen:
- Located in the abdomen
- Filters blood and removes old red blood cells
- Contains red pulp (contain macrophages and red blood cells) and white pulp (contains lymphatic tissue surrounding arteries)
- Destroys old red blood cells
- Stores lymphocytes
- Acts as a blood reservoir
-
Thymus Gland:
- Located in the mediastinum (between the lungs)
- Produces and matures T lymphocytes (T cells)
- Stops growing at age 1
- Decreases in size at age 60
Immunity
- Immunity: The body's ability to resist infection and disease
-
Innate Immunity: Present at birth, provides a general defense against pathogens
- Includes physical barriers (skin and mucous membranes), chemical barriers (lysozyme, mucous membranes), and cellular defenses (phagocytes, natural killer cells)
-
Adaptive Immunity: Develops after birth, provides a specific defense against pathogens
- Involves lymphocytes (B and T cells) and antigen-specific responses
Innate Immunity
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First Line of Defense: Physical barriers such as skin, mucous membranes, and cilia
-
Chemical Mediators:
- Lysozyme: Enzyme found in tears and saliva that breaks down bacterial cell walls
- Mucous Membranes: Line body cavities, trap microbes
- Histamine: Promotes inflammation and vasodilation
- Interferons: Proteins that interfere with viral replication
-
Cells of the Immune System:
-
Phagocytic Cells: Eat or engulf other cells
- Neutrophils: First responders to infection but die quickly
- Macrophages: Highly phagocytic cells found in tissues, can also present antigens to lymphocytes
- Eosinophils: Fight parasites, allergies, and inflammation
- Basophils: Release histamine and other inflammatory chemicals
- Mast Cells: Found in tissues, release histamine
- Natural Killer Cells: Recognize and kill infected cells and cancer cells
- Inflammatory Response: Localized response to injury or infection, characterized by redness, swelling, heat, and pain; involves chemical mediators, phagocytes, and blood clotting.
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Phagocytic Cells: Eat or engulf other cells
Adaptive Immunity
- Antigen: Any substance that can trigger an immune response
- Self-Antigen: A molecule produced by the person's body that stimulates an immune system response
- Antibody (Immunoglobulin): Proteins produced by B cells that recognize and bind to specific antigens.
Origin and Development of Lymphocytes
- Stem Cells: Found in red bone marrow, give rise to all blood cells including lymphocytes
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Lymphocytes: White blood cells that are key to adaptive immunity, originate from stem cells
- Differentiate into B cells and T cells
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B Cells: Type of lymphocyte involved in antibody-mediated immunity
- Mature in the red bone marrow
- Produce antibodies
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T Cells: Type of lymphocyte involved in cell-mediated immunity
- Mature in the thymus gland
- Recognize and destroy infected cells
- 4 main types:
- Helper T Cells (CD4+): Activate B cells and cytotoxic T cells
- Cytotoxic T Cells (CD8+): Kill infected cells and cancer cells
- Regulatory T Cells: Suppress the immune response
- Memory T Cells: Remain after an infection, allow for quicker response to future exposures
Antigen Recognition
- Lymphocytes have antigen receptors on their surface
- B-cell receptors (BCRs) on B cells
- T-cell receptors (TCRs) on T cells
- Each receptor only binds with a specific antigen
The MHC Molecule
- MHC (Major Histocompatibility Complex): Group of genes that code for proteins found on the surface of cells
- MHC Class I molecules present antigens to cytotoxic T cells (CD8+)
- MHC Class II molecules present antigens to helper T cells (CD4+)
- MHC molecules hold and present antigens on the surface of cells
- MHC molecules must be matched for organ transplantation
Cytokines
- Proteins secreted by cells that regulate neighboring cells
- Interleukin-1 (IL-1): Released by macrophages, stimulates helper T cells (CD4+)
Proliferation of Helper T Cells
- Macrophages (Antigen Presenting Cells): Phagocytize antigens, process the antigen and display it on the surface of the cell (MHC Class II)
- Helper T cells (CD4+):
- Recognize the antigen presented on the Macrophage (MHC Class II/antigen complex)
- Costimulation by Interleukin-1
- Secrete interleukin-2, which stimulates their own proliferation
Proliferation of Lymphocytes
- Helper T cells (CD4+)
- Cytotoxic T cells (CD8+)
- B cells
- All undergo proliferation when exposed to their specific antigens
- Proliferation amplifies the immune response.
Proliferation of B Cells
- Helper T cells (CD4+) interact with B cells that have already encountered their specific antigen
- Costimulation from helper T cells, including interleukin-2, causes B cells to proliferate
- Daughter cells become either Plasma cells (produce antibodies) or Memory B cells (retain memory of the antigen)
Dual Nature of the Immune System
- Lymphocytes give rise to 2 types of immune responses: antibody-mediated and cell-mediated
- Antigens can trigger both types of responses
Antibody-Mediated Immunity (Humoral Immunity)
- Effective against antigens in body fluids such as blood and lymph
- Effective against bacteria, viruses, and toxins
- Uses B cells to produce antibodies (immunoglobulins)
Antibody Structure
- Y-Shaped protein
- Variable Region: Two arms of the Y, bind to specific epitopes on antigens
- Constant Region: Stem of the Y, determines the antibody's class (IgG, IgM, IgA, IgE, IgD)
5 Classes of Immunoglobulins
- IgG: Most abundant antibody, crosses the placenta, activates complement, neutralizes toxins
- IgM: First antibody produced in an immune response, activates complement, acts as an antigen-binding receptor on B cells
- IgA: Found in secretions like saliva, tears, and breast milk
- IgE: Involved in allergic reactions
- IgD: Functions as an antigen-binding receptor on B cells
Effects of Antibodies
- Neutralize antigens
- Agglutination (bind antigens together)
- Activate complement
- Initiate the release of inflammatory chemicals
- Facilitate phagocytosis
Antibody Production
-
Primary Response: Initial exposure to an antigen
- B cells divide and give rise to plasma cells (antibody production) and memory B cells
- Takes 3 to 14 days for antibody levels to reach peak, person may develop symptoms of illness
-
Secondary Response: Subsequent exposure to the same antigen
- Memory B cells quickly divide to produce plasma cells
- Faster and more robust response, antibody levels reach peak in 2 to 3 days, person usually does not develop symptoms
Cell-Mediated Immunity
- Used against antigens in cells and tissues
- Effective against intracellular bacteria, viruses, fungi, and protozoa
- Uses T cells (killer T cells, helper T cells, regulatory T cells)
Types of T Cells for Cell-Mediated Immunity
- Helper T Cells (CD4+): Activate macrophages, help form B cells, promote production of cytotoxic T cells (CD8+)
- Cytotoxic T Cells (CD8+): Kill infected cells
- Regulatory T Cells: Suppress the immune response
- Memory T Cells: Remain after an infection and allow for quicker response to future exposures
Proliferation of Cytotoxic T Cells
- MHC Class I molecules present antigens to cytotoxic T cells (CD8+)
- Cytotoxic T cells (CD8+) recognize the antigen/MHC class I complex
- Costimulation by CD8 and other surface molecules and cytokines from helper T cells, including Interleukin-2
- Activated cytotoxic T cells (CD8+) undergo proliferation
Stimulation and Effects of T Cells
- Activated cytotoxic T cells (CD8+) release cytotoxic chemicals that destroy infected cells or tumor cells
Immune Interactions
- Innate and adaptive immune systems work together to protect the body.
- Innate immune system provides the first line of defense.
- Adaptive immune system provides a more specific and targeted response.
Types of Adaptive Immunity
-
Natural Adaptive Immunity:
- Active: Exposure to an antigen through natural means (getting sick).
- Passive: Transfer of antibodies from mother to baby (across the placenta or through breast milk).
-
Artificial Adaptive Immunity:
- Active: Exposure to an antigen through vaccination (e.g., flu shot)
- Passive: Injection of antibodies produced by another person or animal (e.g., antivenom)
Ways to Acquire Adaptive Immunity
- Active Immunity: Immunity provided by the individual's own immune system
- Natural Active Immunity: Acquired through natural exposure to an antigen.
- Artificial Active Immunity: Acquired through vaccination.
- Passive Immunity: Immunity transferred from another person or animal
- Natural Passive Immunity: Antibodies transferred from mother to baby (across the placenta or through breast milk).
- Artificial Passive Immunity: Antibodies produced by another person or animal are injected.
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Description
Explore the essential functions and components of the lymphatic system. This quiz covers topics including lymph transport, drainage mechanisms, and the roles of lymph nodes, spleen, and thymus in immune response. Test your knowledge on how this vital system maintains fluid balance and fights infections.
