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What are pathogens?
What are pathogens?
The lymphatic system primarily circulates blood.
The lymphatic system primarily circulates blood.
False
What is the main organ system that defends the body against disease?
What is the main organ system that defends the body against disease?
Lymphatic system
Lymph is richer in dietary __________ as it exits the gastrointestinal tract.
Lymph is richer in dietary __________ as it exits the gastrointestinal tract.
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Match the following lymphatic components with their functions:
Match the following lymphatic components with their functions:
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What is the primary function of lymphatic capillaries?
What is the primary function of lymphatic capillaries?
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Lymphatic vessels can exit lymph nodes directly into the bloodstream.
Lymphatic vessels can exit lymph nodes directly into the bloodstream.
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What is the name of the lipid-rich lymph absorbed by specialized lymphatic capillaries in the small intestines?
What is the name of the lipid-rich lymph absorbed by specialized lymphatic capillaries in the small intestines?
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The endothelial cell edges of lymphatic capillaries allow fluid to enter but not ____.
The endothelial cell edges of lymphatic capillaries allow fluid to enter but not ____.
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Match the following structures with their corresponding functions or descriptions:
Match the following structures with their corresponding functions or descriptions:
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What percentage of fluid is returned to circulation via the lymphatic system?
What percentage of fluid is returned to circulation via the lymphatic system?
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The right lymphatic duct is found in all individuals.
The right lymphatic duct is found in all individuals.
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What structure collects lymph from various parts of the body before draining into the superior vena cava?
What structure collects lymph from various parts of the body before draining into the superior vena cava?
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The primary lymphatic organ located in the body is the ____ _____.
The primary lymphatic organ located in the body is the ____ _____.
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Which of the following correctly identifies a type of lymphoid tissue?
Which of the following correctly identifies a type of lymphoid tissue?
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What is the process called that ensures T cells can bind to MHC-I and continue their development?
What is the process called that ensures T cells can bind to MHC-I and continue their development?
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Vaccination is a form of passive immunity.
Vaccination is a form of passive immunity.
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Name one virus that causes immunological amnesia.
Name one virus that causes immunological amnesia.
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Vaccines provide a ________ version of a foreign antigen that stimulates the immune response.
Vaccines provide a ________ version of a foreign antigen that stimulates the immune response.
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Match the following concepts with their descriptions:
Match the following concepts with their descriptions:
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What type of antibodies do infants receive through the placenta?
What type of antibodies do infants receive through the placenta?
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T cells that bind to self-peptides are usually allowed to mature.
T cells that bind to self-peptides are usually allowed to mature.
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Which immune cells does HIV primarily infect?
Which immune cells does HIV primarily infect?
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During allergic reactions, mast cells ________ upon second exposure to the allergen.
During allergic reactions, mast cells ________ upon second exposure to the allergen.
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What are the three types of homeostatic imbalances in the immune system?
What are the three types of homeostatic imbalances in the immune system?
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What type of cells undergo clonal selection after activation by an antigen?
What type of cells undergo clonal selection after activation by an antigen?
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Effector cells are long-lived and play a crucial role in immune memory.
Effector cells are long-lived and play a crucial role in immune memory.
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What is the primary role of memory cells?
What is the primary role of memory cells?
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Antigen-presenting cells (APCs) process _____ antigens by ingesting them.
Antigen-presenting cells (APCs) process _____ antigens by ingesting them.
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Match the following types of T cells with their primary functions:
Match the following types of T cells with their primary functions:
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Which of the following is NOT a component of antibodies?
Which of the following is NOT a component of antibodies?
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Memory cells are activated by foreign antigens presented by APCs.
Memory cells are activated by foreign antigens presented by APCs.
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What do CTLs secrete to carry out their function?
What do CTLs secrete to carry out their function?
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The _____ immune response occurs after the first exposure to an antigen.
The _____ immune response occurs after the first exposure to an antigen.
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Which component is involved in recognizing specific protein shapes on antigens?
Which component is involved in recognizing specific protein shapes on antigens?
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All lymphocytes can act as antigen-presenting cells.
All lymphocytes can act as antigen-presenting cells.
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How do B cells contribute to antibody-mediated immunity?
How do B cells contribute to antibody-mediated immunity?
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A second signal is usually provided by _____ for full T cell activation.
A second signal is usually provided by _____ for full T cell activation.
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What is the role of antibodies in the immune response?
What is the role of antibodies in the immune response?
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Match the following types of immune responses with their characteristics:
Match the following types of immune responses with their characteristics:
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What process occurs after a phagocyte binds to an invader?
What process occurs after a phagocyte binds to an invader?
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The major histocompatibility complex (MHC) antigens are present on all body cells including erythrocytes.
The major histocompatibility complex (MHC) antigens are present on all body cells including erythrocytes.
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What type of immune response is characterized by increased blood flow and vascular permeability?
What type of immune response is characterized by increased blood flow and vascular permeability?
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The process of leukocytes squeezing through intercellular gaps is called __________.
The process of leukocytes squeezing through intercellular gaps is called __________.
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Match the following immune cells with their functions:
Match the following immune cells with their functions:
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Which is not a characteristic sign of inflammation?
Which is not a characteristic sign of inflammation?
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Chemical signals like histamine are responsible for increasing blood flow to injured tissues.
Chemical signals like histamine are responsible for increasing blood flow to injured tissues.
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What type of pathogens does cell-mediated immunity primarily protect against?
What type of pathogens does cell-mediated immunity primarily protect against?
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Once the phagosome fuses with a lysosome, it is referred to as a __________.
Once the phagosome fuses with a lysosome, it is referred to as a __________.
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What are the proteins that promote vasodilation along with histamine called?
What are the proteins that promote vasodilation along with histamine called?
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Which type of cells give rise to blood cells including leukocytes?
Which type of cells give rise to blood cells including leukocytes?
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The thymus is a unilobed gland.
The thymus is a unilobed gland.
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Antibody-mediated immunity is also known as humoral immunity.
Antibody-mediated immunity is also known as humoral immunity.
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What do T cells express that facilitates their identification and immune signaling?
What do T cells express that facilitates their identification and immune signaling?
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What type of lymphocytes become immunocompetent in the thymus?
What type of lymphocytes become immunocompetent in the thymus?
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The response of the immune system to tissue damage is known as __________ immunity.
The response of the immune system to tissue damage is known as __________ immunity.
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The spleen is the ______ mass of lymphatic tissue in the body.
The spleen is the ______ mass of lymphatic tissue in the body.
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Match the following immune responses with their descriptions:
Match the following immune responses with their descriptions:
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What is the outer structure of the lymph nodes called?
What is the outer structure of the lymph nodes called?
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Innate immunity is specific and slower than adaptive immunity.
Innate immunity is specific and slower than adaptive immunity.
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Name two internal defenses of the innate immune system.
Name two internal defenses of the innate immune system.
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Cilia in the respiratory tract help sweep ____ through the respiratory system.
Cilia in the respiratory tract help sweep ____ through the respiratory system.
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Match the following types of immune cells with their functions:
Match the following types of immune cells with their functions:
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What does the red pulp of the spleen primarily contain?
What does the red pulp of the spleen primarily contain?
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Phagocytes are cells that engulf other cells or large particles to destroy them.
Phagocytes are cells that engulf other cells or large particles to destroy them.
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What protein disrupts bacterial membranes and is contained in tears?
What protein disrupts bacterial membranes and is contained in tears?
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The first line of defense in innate immunity includes keratinized stratified __________ epithelium.
The first line of defense in innate immunity includes keratinized stratified __________ epithelium.
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What lymphatic organ is located in the left hypochondriac region of the abdomen?
What lymphatic organ is located in the left hypochondriac region of the abdomen?
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Study Notes
Lymphatic System
- The lymphatic system is the main organ system for immunity, defending against disease and damage.
- Immunity is resistance to damage or disease; susceptibility is vulnerability to damage or disease.
- Pathogens are disease-causing microorganisms (bacteria, fungi, viruses, parasites).
- The lymphatic system comprises lymph plasma, vessels, and organs that transport lymph. It has three main functions:
- Circulates and drains excess body fluids.
- Defends against disease and damage.
- Transports dietary lipids.
- Lymph is richer in dietary lipids exiting the GI tract than interstitial fluid or blood.
- Lymph is carried in lymphatic vessels, while interstitial fluid is outside vessels.
- Lymph is filtered through lymphoid tissues and organs.
- The main difference between lymph and interstitial fluid is location; lymph is found around lymphatic vessels, while interstitial fluid is around cells.
- Lymph circulation begins at lymphatic capillaries between tissue cells.
- Capillary ends overlap; IF pressure > vessel pressure = fluid enters.
- Lymph capillaries are anchored to surrounding tissue via anchoring filaments. Excess tissue fluid stretches the capillaries, allowing more fluid entry.
- Specialized lymphatic capillaries in the small intestine (lacteals) absorb dietary lipids forming chyle (creamy white lymph).
- Lymphatic capillaries merge to form lymphatic vessels.
- Lymphatic vessels carry lymph to lymph nodes and lymphoid tissue, filtering lymph plasma.
- Lymph trunks form from lymphatic vessels exiting lymph nodes, draining lymph from specific body regions.
- Lymph trunks sometimes merge into lymphatic ducts.
- The right lymphatic duct is not universal, often 3 independent trunks draining into the right subclavian vein.
- The thoracic duct is the main lymph return pathway to circulation, originating at the cisterna chyli and draining into the left subclavian vein.
- The brachiocephalic veins return lymph fluid as blood plasma to the heart.
- Right lymph drains into the right brachiocephalic vein.
- Left lymph drains into the left brachiocephalic vein via the thoracic duct and the bronchomediastinal trunk.
- Brachiocephalic veins drain into the superior vena cava.
- Lymph drainage pattern: right lymphatic duct/trunks drain head, neck, and right upper limb; thoracic duct drains the rest.
- The lymphatic system returns ~15% (3L/day) of filtered fluid to circulation.
- Skeletal muscle and respiratory pumps move lymph.
Lymphatic Organs and Tissues
- Lymphatic organs are categorized as primary and secondary.
- Lymphatic tissue lacks a capsule and includes mucosa-associated lymphoid tissue (MALT) within mucous membrane lamina propria, aggregated lymphoid follicles (Peyer's patches) in the ileum, and tonsils (pharyngeal, palatine, lingual).
- Primary lymphatic organs:
- Red bone marrow: Site of hematopoiesis (blood cell formation), including B and T lymphocytes development from multipotent stem cells.
- Thymus: Bilobed gland in the mediastinum; shrinks with age; site of T lymphocyte maturation and immunocompetence.
- The thymus cortex contains epithelial cells training immature T cells; the medulla contains mature T cells and thymic corpuscles (role unknown).
- Secondary lymphatic organs:
- Spleen: Largest lymphatic organ in the left hypochondriac region, with stroma (connective tissue capsule and trabeculae) and parenchyma (white and red pulp).
- White pulp: Lymphatic tissue, surrounds splenic arteries; monitors blood and defends against infection.
- Red pulp: Erythrocytes, macrophages, lymphocytes, etc.; removes worn-out blood cells, participates in hemopoiesis, stores platelets.
- Lymph nodes: Bean-shaped organs with a capsule, trabeculae, cortex (lymphoid nodules of B cells), para-cortex (T cells and dendritic cells), and medulla (plasma cells and macrophages). Lymph enters afferent and exits efferent vessels.
- Spleen: Largest lymphatic organ in the left hypochondriac region, with stroma (connective tissue capsule and trabeculae) and parenchyma (white and red pulp).
Immunity
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The immune system is divided into innate and adaptive immunity.
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Innate immunity is non-specific and rapid, found in all animals. Adaptive immunity is specific, requiring activation, found only in vertebrates.
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Innate immunity includes external and internal defenses.
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External defenses are the first line of defense: epidermis (keratinized stratified squamous epithelium), sebum (acidic), sweat (salty), mucus membranes, hair, cilia, tears and other fluids (lysosome), and waste elimination.
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Internal defenses (if external fail), include: antimicrobial substances (interferons, complement proteins, iron-binding proteins, AMPs), natural killer cells (releasing perforin and granzymes), and phagocytes (neutrophils, macrophages).
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Phagocytosis: chemotaxis, adherence, ingestion (phagosome), digestion (phagolysosome), killing (oxidative burst), and disposal.
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Inflammation is a nonspecific immune response to tissue injury: characterized by pain, redness, immobility, swelling, and heat (PRISH) due to histamine, kinins, prostaglandins, leukotrienes, and complement proteins signaling increased blood flow, vascular permeability, and leukocyte recruitment.
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Fever is elevated body temperature, potentially beneficial against infection as it can denature pathogen proteins.
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Adaptive immunity has two arms: cell-mediated (CTLs directly kill invaders) and antibody-mediated (antibodies enhance phagocytosis and lysis).
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Lymphocytes recognize specific foreign "antigens" with antigen receptors.
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Cellular activation requires antigen processing and presentation to lymphocytes.
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Exogenous antigens are processed and presented by antigen-presenting cells (APCs, e.g., B cells, macrophages) via MHC-II.
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Endogenous antigens within body cells are processed and presented by APCs via MHC-I.
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T cells (CTLs, HTLs) activate upon antigen recognition (TCRs bind to antigen-MHC complexes); require costimulation(cytokines) for full activation.
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CTLs develop into effector and memory cells during clonal selection.
- CTLs release perforin and granzymes for lysis and apoptosis of infected cells.
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HTLs develop into effector and memory cells during clonal selection.
- HTLs stimulate other lymphocytes, including B cells for antibody-mediated responses.
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Antibody-mediated immunity involves B cells processing exogenous antigens and presenting them via MHC-II. Activated B cells (plasma cells) produce antibodies to enhance pathogens killing and clearance through mechanisms like neutralization and precipitation, complement activation.
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Adaptive immunity generates memory.
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Primary response is slower, subsequent exposures elicit a faster, stronger secondary response due to memory cells.
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Vaccines provide immunity through inoculation with a harmless antigen.
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Immunological amnesia is a condition whereby a virus disables immunologic memory via infection of macrophages or lymphocytes.
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Self-recognition depends on the thymus positive selection of T-cells binding to MHC and negative selection eliminating those that react to self-peptide antigens. Failures of self-tolerance can result in autoimmunity.
Homeostatic Imbalances of the Immune System
- Immunodeficiencies (e.g., AIDS), autoimmune disorders, and hypersensitivities (allergies) can occur.
- AIDS results from HIV infection, primarily affecting CD4+ helper T cells; rendering affected individuals susceptible to infections and cancers.
- Hypersensitivities involving an abnormal response to foreign antigens (allergies) involve antigen stimulation, antibody binding to mast cells and subsequent release of histamine. This leads to anaphylaxis (systemic inflammation).
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Description
Explore the essential functions of the lymphatic system in the body, including its role in immunity, the transport of lymph, and its components. This quiz covers the structure and importance of lymphatic vessels, organs, and their interaction with bodily fluids. Test your understanding of how this system defends against diseases and circulates dietary lipids.
