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Questions and Answers
What is the primary role of the lymphatic system?
What is the primary role of the lymphatic system?
What are pathogens defined as?
What are pathogens defined as?
Which of the following correctly characterizes lymph compared to interstitial fluid?
Which of the following correctly characterizes lymph compared to interstitial fluid?
What is one of the main functions of the lymphatic system?
What is one of the main functions of the lymphatic system?
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What does susceptibility refer to in the context of the lymphatic system?
What does susceptibility refer to in the context of the lymphatic system?
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What significant function does the thymus serve in the immune system?
What significant function does the thymus serve in the immune system?
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What key component is found in the outer cortex of the thymus?
What key component is found in the outer cortex of the thymus?
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What does the red pulp in the spleen primarily contain?
What does the red pulp in the spleen primarily contain?
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Which part of the lymph node primarily contains B cells?
Which part of the lymph node primarily contains B cells?
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What is the primary role of the innate immune system?
What is the primary role of the innate immune system?
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Which substance is known to catabolize sebum and contribute to skin acidity?
Which substance is known to catabolize sebum and contribute to skin acidity?
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How does lysozyme function in the immune response?
How does lysozyme function in the immune response?
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Natural killer cells (NKCs) mainly target which type of cells?
Natural killer cells (NKCs) mainly target which type of cells?
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Which feature is characteristic of secondary lymphatic organs?
Which feature is characteristic of secondary lymphatic organs?
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What is the primary role of macrophages in the immune response?
What is the primary role of macrophages in the immune response?
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What occurs during chemotaxis in the immune response?
What occurs during chemotaxis in the immune response?
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Which of these describes the primary lymphatic organs?
Which of these describes the primary lymphatic organs?
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What is the largest mass of lymphatic tissue in the body?
What is the largest mass of lymphatic tissue in the body?
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What prevents interstitial fluid from exiting lymphatic capillaries?
What prevents interstitial fluid from exiting lymphatic capillaries?
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What specialized lymphatic capillaries are responsible for absorbing dietary lipids in the intestines?
What specialized lymphatic capillaries are responsible for absorbing dietary lipids in the intestines?
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What structure is the largest lymph vessel in the body?
What structure is the largest lymph vessel in the body?
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What assists in moving fluid through lymphatic vessels?
What assists in moving fluid through lymphatic vessels?
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What is the primary function of lymphatic vessels?
What is the primary function of lymphatic vessels?
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Which lymphatic structure drains lymph from the head, neck, and right upper limb?
Which lymphatic structure drains lymph from the head, neck, and right upper limb?
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Which of the following structures is not a class of lymphatic organ?
Which of the following structures is not a class of lymphatic organ?
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What type of lymphatic tissue lacks a connective tissue capsule?
What type of lymphatic tissue lacks a connective tissue capsule?
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What is the approximate percentage of fluid that the lymphatic system returns to circulation?
What is the approximate percentage of fluid that the lymphatic system returns to circulation?
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Which of the following is absorbed in the form of chyle by specialized lymphatic capillaries?
Which of the following is absorbed in the form of chyle by specialized lymphatic capillaries?
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What type of immunity is developed through exposure to foreign antigens, leading to the synthesis of antibodies?
What type of immunity is developed through exposure to foreign antigens, leading to the synthesis of antibodies?
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What process eliminates T cells that improperly bind to self-peptides?
What process eliminates T cells that improperly bind to self-peptides?
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Which of the following diseases is exemplified by the loss of immunological memory due to a viral infection?
Which of the following diseases is exemplified by the loss of immunological memory due to a viral infection?
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Which cells are preferentially infected by the human immunodeficiency virus (HIV)?
Which cells are preferentially infected by the human immunodeficiency virus (HIV)?
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During which phase of T cell maturation does positive selection occur?
During which phase of T cell maturation does positive selection occur?
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What is the primary consequence of a failure in self-tolerance within the immune system?
What is the primary consequence of a failure in self-tolerance within the immune system?
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What is released by mast cells during degranulation in an allergic reaction?
What is released by mast cells during degranulation in an allergic reaction?
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What type of therapy involves the administration of pre-made antibodies?
What type of therapy involves the administration of pre-made antibodies?
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Which immune disorder results from an inadequate immune response to infections?
Which immune disorder results from an inadequate immune response to infections?
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Which vaccine is known for preventing measles, mumps, and rubella?
Which vaccine is known for preventing measles, mumps, and rubella?
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What is the role of effector cells during the immune response?
What is the role of effector cells during the immune response?
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What type of antigens are processed by antigen-presenting cells (APCs)?
What type of antigens are processed by antigen-presenting cells (APCs)?
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What is the primary function of cytotoxic T lymphocytes (CTLs)?
What is the primary function of cytotoxic T lymphocytes (CTLs)?
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What triggers the activation of T cell receptors (TCRs) on cytotoxic T lymphocytes?
What triggers the activation of T cell receptors (TCRs) on cytotoxic T lymphocytes?
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How do antibodies enhance the immune response?
How do antibodies enhance the immune response?
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Which cells are responsible for the recognition of exogenous antigens bound to MHC-II molecules?
Which cells are responsible for the recognition of exogenous antigens bound to MHC-II molecules?
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What is a crucial requirement for full activation of T cells during immune responses?
What is a crucial requirement for full activation of T cells during immune responses?
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What is the role of the pseudopods in phagocytosis?
What is the role of the pseudopods in phagocytosis?
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Memory B cells are primarily responsible for which aspect of the immune response?
Memory B cells are primarily responsible for which aspect of the immune response?
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What is the primary role of helper T cells in the immune system?
What is the primary role of helper T cells in the immune system?
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Which component is responsible for increasing vascular permeability during inflammation?
Which component is responsible for increasing vascular permeability during inflammation?
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During clonal selection, what type of lymphocyte is produced to actively combat infections?
During clonal selection, what type of lymphocyte is produced to actively combat infections?
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Which type of immune response is characterized by a tailored reaction to specific pathogens?
Which type of immune response is characterized by a tailored reaction to specific pathogens?
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Which protein is required for helper T cells to interact with MHC-II molecules during activation?
Which protein is required for helper T cells to interact with MHC-II molecules during activation?
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What is the primary function of the phagolysosome in the immune response?
What is the primary function of the phagolysosome in the immune response?
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What describes the secondary immune response compared to the primary immune response?
What describes the secondary immune response compared to the primary immune response?
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Which type of lymphocyte is primarily involved in cell-mediated immunity?
Which type of lymphocyte is primarily involved in cell-mediated immunity?
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What characteristic does the major histocompatibility complex (MHC) provide?
What characteristic does the major histocompatibility complex (MHC) provide?
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What is the primary importance of immunological memory?
What is the primary importance of immunological memory?
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How do antigen receptors instruct lymphocytes to respond to pathogens?
How do antigen receptors instruct lymphocytes to respond to pathogens?
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What physiological process is responsible for the 'heat' characteristic of inflammation?
What physiological process is responsible for the 'heat' characteristic of inflammation?
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How do leukocytes follow the signals to the site of tissue damage?
How do leukocytes follow the signals to the site of tissue damage?
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What triggers the hypothalamus to induce a fever during infection?
What triggers the hypothalamus to induce a fever during infection?
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What defines the characteristic signs and symptoms of inflammation, commonly referred to as PRISH?
What defines the characteristic signs and symptoms of inflammation, commonly referred to as PRISH?
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What type of immunity specifically guards against extracellular pathogens?
What type of immunity specifically guards against extracellular pathogens?
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Which of the following best describes the role of kinins in the inflammatory response?
Which of the following best describes the role of kinins in the inflammatory response?
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Which cell type acts to cause cytolysis of invaders in the immune response?
Which cell type acts to cause cytolysis of invaders in the immune response?
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What is the function of the Cluster of Differentiation 4 (CD4) protein found on Helper T cells?
What is the function of the Cluster of Differentiation 4 (CD4) protein found on Helper T cells?
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What leads to the formation of residual bodies inside phagocytes?
What leads to the formation of residual bodies inside phagocytes?
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Study Notes
Lymphatic System Overview
- The lymphatic system is the main organ system that defends against disease.
- Immunity is resistance to damage or disease; susceptibility is vulnerability to disease.
- Pathogens are disease-causing microorganisms (bacteria, fungi, viruses, parasites).
- The lymphatic system consists of lymph (lymph plasma), vessels, and organs that transport and contain it.
- Three main functions:
- Circulates and drains excess body fluids.
- Defends against disease and damage.
- Transports dietary lipids.
- Lymph is similar to interstitial fluid and blood but richer in lipids exiting the GI tract.
Lymph Circulation
- Lymph circulation begins at lymphatic capillaries.
- Capillary tips permit interstitial fluid (IF) entry, but not exit, due to overlapping endothelial cells.
- IF pressure > lymph pressure causes IF to enter lymphatic vessels.
- Anchoring filaments connect lymphatic capillaries to surrounding tissue cells, widening capillaries with tissue swelling.
- Specialized lymphatic capillaries in the small intestine (lacteals) absorb dietary lipids, forming creamy white chyle.
- Lymphatic capillaries merge into larger lymphatic vessels and eventually trunks.
- Lymph trunks drain lymph from specific regions.
- Lymph trunks may merge to form lymphatic ducts (right lymphatic duct, thoracic duct).
- The thoracic duct drains the majority of lymph to the left subclavian vein.
- The right lymphatic duct or trunks drain lymph from the head, neck, and right upper limb to the right brachiocephalic vein.
- The thoracic duct drains the rest of the body's lymph to the left brachiocephalic vein.
Fluid Return to Circulation
- ~15% body fluid (~3 L/day) is returned to circulation via the lymphatic system.
- Skeletal muscle and respiratory pumps move lymphatic fluid.
Lymphatic Organs and Tissues
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Lymphatic organs are classified into primary and secondary organs.
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Lymphatic tissues lack a capsule and include mucosa-associated lymphoid tissue (MALT), aggregated lymphoid follicles (Peyer's patches in the ileum), tonsils (pharyngeal, palatine, lingual).
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Primary lymphatic organs:
- Red bone marrow: site of stem cell formation of leukocytes (B and T lymphocytes).
- Thymus: bilobed gland where T lymphocytes mature.
- Cortex: contains epithelial cells training immature T cells.
- Medulla: contains mature T cells; thymic corpuscles (function unknown).
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Secondary lymphatic organs:
- Spleen: Largest lymphatic organ in the left hypochondriac region.
- Stroma: capsule, trabeculae, parenchyma (white and red pulp).
- White pulp: lymphocytes and macrophages that monitor and defend against infection.
- Red pulp: erythrocytes, macrophages, lymphocytes; removes old/damaged blood cells; participates in hemopoiesis; stores platelets.
- Lymph nodes: bean-shaped, clustered organs with a capsule and trabeculae.
- Parenchyma: cortex (lymph nodules of B cells), paracortex (T cells, dendritic cells), medulla (plasma cells, macrophages).
- Lymph enters through afferent vessels and exits via efferent vessels.
- Spleen: Largest lymphatic organ in the left hypochondriac region.
Innate Immunity
- Innate immunity is nonspecific, fast, and found in all animals.
- External defenses:
- Skin (physical barrier, acidic/salty environment).
- Mucous membranes (trapping invaders, cilia).
- Fluids (lysozyme in tears).
- Internal defenses:
- Antimicrobial substances (interferons, complement proteins, iron-binding proteins, AMPs).
- Natural killer cells (NKCs): induce apoptosis (perforins, granzymes).
- Phagocytes (engulf and destroy invaders; neutrophils and macrophages).
- Phagocytosis steps: chemotaxis, adherence, ingestion, digestion, killing.
- Inflammation: response to tissue damage, with PRISH (pain, redness, immobility, swelling, heat).
- Histamine, kinins, prostaglandins, leukotrienes, and complement proteins are involved.
- Fever: elevated body temperature to hinder pathogen reproduction.
Adaptive Immunity
- Adaptive immunity is specific, found only in vertebrates.
- Lymphocytes use antigen receptors to identify specific antigens.
- T cells express CD4 (helper T lymphocytes) or CD8 (cytotoxic T lymphocytes).
- Major Histocompatibility Complex (MHC) antigens (MHC-I on all cells except erythrocytes, MHC-II on antigen-presenting cells).
- Two arms of adaptive immunity: cell-mediated (CTLs) and antibody-mediated (B cells).
Cell-Mediated Immunity
- CTLs recognize endogenous antigens (inside body cells) presented on MHC-I.
- CTL activation requires costimulation (cytokines) for full activation.
- CTLs induce apoptosis or lysis in infected cells.
Antibody-Mediated Immunity
- B cells process and present exogenous antigens (outside body cells) on MHC-II to activate helper T cells.
- Activated B cells differentiate into plasma cells, producing antibodies against specific antigens to enhance phagocytosis, neutralize antigens, agglutinate antigens and precipitate them activation complement.
Immunological Memory
- Primary immune response: first exposure takes days to increase antibody titer.
- Secondary immune response: subsequent exposure is faster and stronger due to memory cells.
- Vaccines use harmless versions of antigens to stimulate a primary immune response.
Self-Recognition and Self-Tolerance
- Positive selection (thymus) ensures T cells recognize MHC.
- Negative selection (thymus) eliminates T cells reacting to self-antigens.
- Failure of self-tolerance results in autoimmune disorders.
Homeostatic Imbalances
- Immunodeficiencies, autoimmune disorders, and hypersensitivities are discussed.
- AIDS, an immunodeficiency, is caused by HIV.
- Allergies are an example of hypersensitivity.
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Description
Explore the essential components and functions of the lymphatic system in this quiz. Learn how it helps defend the body against disease, circulates excess fluids, and transports lipids. Test your knowledge on lymph circulation and its role in immunity.
