Lymphatic System Overview
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Questions and Answers

What are pathogens?

  • Healthy microorganisms
  • Nutrients for the body
  • Cells that promote healing
  • Disease-causing microorganisms (correct)

Immunity refers to vulnerability to damage or disease.

False (B)

Name the primary organ system that defends the body against disease.

lymphatic system

Lymph is richer in dietary __________ as it exits the GI tract.

<p>lipids</p> Signup and view all the answers

Match the following functions to the lymphatic system:

<p>Circulates excess body fluids = Function 1 Defends the body against disease = Function 2 Transports dietary lipids = Function 3</p> Signup and view all the answers

What is the primary function of lymphatic capillaries?

<p>Sample interstitial fluid and return filtered fluid to circulation (C)</p> Signup and view all the answers

Lymphatic vessels only drain lymph from the lower body.

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

What do we call the fluid collected in lipid-rich lymph?

<p>chyle</p> Signup and view all the answers

The main lymphatic duct draining the majority of the body is the _____.

<p>thoracic duct</p> Signup and view all the answers

Match the lymphatic organs with their functions:

<p>Tonsils = Filter pathogens from ingested substances Lacteals = Absorb lipids from the small intestine MALT = Protect mucous membranes Red Bone Marrow = Produce lymphocytes</p> Signup and view all the answers

Which lymphatic vessel is not universally present in all individuals?

<p>Right lymphatic duct (C)</p> Signup and view all the answers

Endothelial cell edges of lymphatic capillaries do not allow interstitial fluid to exit.

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

What is the role of skeletal muscle and respiratory pumps in the lymphatic system?

<p>Move fluid through lymphatic vessels</p> Signup and view all the answers

Approximately _____% of fluid is returned to circulation via the lymphatic system.

<p>15</p> Signup and view all the answers

What structure absorbs dietary lipids from digestion?

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

What type of immunity is generated from vaccines?

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

Self-tolerance in adaptive immunity allows the immune system to react to self-antigens.

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

What is the primary immune response stimulated by vaccines?

<p>Production of antibodies</p> Signup and view all the answers

The measles virus can cause immunological ___________ .

<p>amnesia</p> Signup and view all the answers

What happens to T cells that do not bind MHC-I during development?

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

Individuals with HIV are especially susceptible to infections because the virus preferentially infects ___________ cells.

<p>CD4+ T</p> Signup and view all the answers

Match the immune system concepts with their descriptions:

<p>Positive selection = Process allowing T cells that bind MHC-I to mature Negative selection = Elimination of T cells that react to self-antigens Active immunity = Immune response generated by exposure to an antigen Passive immunity = Receiving pre-made antibodies</p> Signup and view all the answers

What is a common example of hypersensitivity in the immune system?

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

Anaphylaxis is a systemic inflammatory response that can occur from a second exposure to an allergen.

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

What is the primary reason for the inability of untreated individuals with HIV to mount adaptive immune responses?

<p>Infection of CD4+ T cells</p> Signup and view all the answers

Which of the following cells are formed in multipotent stem cells?

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

The thymus gland increases in size as a person ages.

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

What type of lymphocytes become immunocompetent in the thymus?

<p>T lymphocytes</p> Signup and view all the answers

The spleen is located in the left __________ region of the abdomen.

<p>hypochondriac</p> Signup and view all the answers

Match the following lymphatic organs with their primary function:

<p>Thymus = Site of T lymphocytes maturation Spleen = Filters blood and removes damaged cells Lymph nodes = Filters lymph and responds to infections</p> Signup and view all the answers

Which component of the immune system is the first line of defense?

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

Cilia in the respiratory tract help trap and sweep harmful particles away.

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

Name one antimicrobial substance produced by the body.

<p>Lysozyme</p> Signup and view all the answers

The __________ pulp in the spleen contains lymphocytes and macrophages.

<p>white</p> Signup and view all the answers

Match the following immune cells with their functions:

<p>Neutrophils = First responders to infection Natural Killer Cells = Attack foreign cells Macrophages = Engulf and destroy pathogens</p> Signup and view all the answers

What is the role of interferons in the immune response?

<p>They have antiviral properties. (A)</p> Signup and view all the answers

Phagocytes are responsible for engulfing and destroying other cells or large particles.

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

What is the function of the red pulp in the spleen?

<p>Removes worn-out blood cells</p> Signup and view all the answers

The external defenses of innate immunity include __________ membranes.

<p>mucous</p> Signup and view all the answers

What is the role of pseudopods in phagocytosis?

<p>To wrap around and engulf invaders (C)</p> Signup and view all the answers

Histamine reduces blood flow to the site of injury.

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

What structure forms when a phagosome fuses with a lysosome?

<p>phagolysosome</p> Signup and view all the answers

The immune response that occurs regardless of the type of pathogen is called __________.

<p>nonspecific</p> Signup and view all the answers

Match the immune cells with their primary roles:

<p>Neutrophils = Phagocytize invaders Natural Killer Cells = Cause cytolysis of infected cells Macrophages = Clean up cell debris Lymphocytes = Specific immune responses</p> Signup and view all the answers

Which of the following proteins enhance leukocyte chemotaxis?

<p>All of the above (D)</p> Signup and view all the answers

Antibody-mediated immunity primarily defends against intracellular pathogens.

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

What happens to blood vessels during inflammation?

<p>They become more permeable.</p> Signup and view all the answers

Inflammation results in the signs and symptoms known as __________.

<p>PRISH</p> Signup and view all the answers

What is the function of CD4 proteins in T lymphocytes?

<p>To act as co-receptors during signaling (A)</p> Signup and view all the answers

All body cells express Class I MHC antigens except for erythrocytes.

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

What are effector cells?

<p>Short-lived lymphocytes that kill invaders (D)</p> Signup and view all the answers

Define chemotaxis in the context of the immune response.

<p>The movement of leukocytes towards chemical signals at the site of tissue damage.</p> Signup and view all the answers

During tissue healing, __________ are proteins that promote vasodilation.

<p>kinins</p> Signup and view all the answers

Memory cells actively kill or attack invaders.

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

What type of antigens are exogenous antigens?

<p>Foreign molecules circulating in fluids.</p> Signup and view all the answers

Match the type of immunity with its characteristic:

<p>Cell-mediated immunity = Directly kills infected cells Humoral immunity = Produces antibodies Innate immunity = Non-specific defense Adaptive immunity = Specific defense</p> Signup and view all the answers

Activated T cells require __________ to fully activate.

<p>costimulation</p> Signup and view all the answers

Match the following cells with their primary function:

<p>B cells = Produce antibodies CTLs = Kill infected cells HTLs = Costimulate other lymphocytes Memory cells = Provide immune memory</p> Signup and view all the answers

What role do CD8 proteins play in CTL activation?

<p>They stabilize the interaction between TCR and MHC-I. (A)</p> Signup and view all the answers

Plasma cells and plasmocytes refer to the same type of cells.

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

What is the primary role of antibodies?

<p>To recognize and neutralize foreign antigens.</p> Signup and view all the answers

The first exposure to an antigens leads to a __________ immune response.

<p>primary</p> Signup and view all the answers

Match the following terms with their definitions:

<p>Antigens = Substances that trigger immune responses Immunological memory = Ability to remember and respond to past infections Cytokines = Proteins that stimulate lymphocyte division Phagocytosis = Ingestion of pathogens by cells</p> Signup and view all the answers

Which type of antigen is presented on MHC-I molecules?

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

Helper T lymphocytes can activate B cells.

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

What are the two populations of lymphocytes produced during clonal selection?

<p>Effector cells and memory cells.</p> Signup and view all the answers

Antigen-presenting cells (APCs) include __________ and macrophages.

<p>B cells</p> Signup and view all the answers

Flashcards

Lymphatic System's Role

The main organ system that defends the body against disease and damage, and transports excess body fluids and dietary lipids.

Lymph vs. Interstitial Fluid

Lymph is interstitial fluid that has entered lymphatic vessels, and is richer in dietary lipids after passing through the gastrointestinal tract.

Pathogens

Disease-causing microorganisms such as bacteria, fungi, viruses, and parasites.

Immunity

Resistance to disease or damage.

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Susceptibility

Vulnerability to disease or damage.

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Lymph circulation

A system that samples interstitial fluid and returns filtered fluid to the bloodstream.

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Lymphatic capillaries

Tiny vessels that begin lymph circulation, where interstitial fluid enters but cannot exit.

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Lacteals

Specialized lymphatic capillaries in the small intestine that absorb dietary lipids (fats).

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Chyle

Lipid-rich lymph, appearing creamy white in color.

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Lymphatic trunks

Larger lymphatic vessels formed by merging lymphatic vessels that drain lymph from specific body regions.

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Right lymphatic duct

A lymphatic duct, usually consisting of 3 trunks, that drains lymph from the right upper body.

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Thoracic duct

The largest lymphatic vessel, draining lymph from most of the body into the left subclavian vein.

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Cisterna chyli

An expanded sac-like structure at the beginning of the thoracic duct, receiving lymph from lower body.

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Lymphatic tissue

Aggregates of immune cells exposed to the external environment, forming lymphatic organs.

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MALT

Mucosa-associated lymphoid tissue, lymphatic tissues found in mucous membranes.

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Red Bone Marrow

A primary lymphatic organ that produces all blood cells, including immune cells, making it a crucial site for immune cell development.

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Thymus

A bilobed primary lymphatic organ located in the chest, where T lymphocytes mature and learn to recognize and destroy foreign invaders.

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T Lymphocytes

White blood cells that develop in the thymus and are critical parts of the adaptive immune system, specifically targeting and destroying infected cells.

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Cortex of the Thymus

The outer region of the thymus where immature T lymphocytes undergo training and selection, learning to distinguish self from non-self.

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Medulla of the Thymus

The inner region of the thymus where mature T lymphocytes reside after completing their training.

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Spleen

A large secondary lymphatic organ located in the abdomen, responsible for filtering blood, removing damaged red blood cells, and housing immune cells.

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White Pulp of the Spleen

Lymphatic tissue within the spleen that encircles splenic arteries, containing lymphocytes and macrophages, to detect and fight off infections in the bloodstream.

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Red Pulp of the Spleen

The area within the spleen that stores red blood cells, macrophages, and other immune cells, responsible for filtering out old and damaged red blood cells.

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Lymph Nodes

Bean-shaped secondary lymphatic organs scattered throughout the body, filtering lymph fluid and housing immune cells that fight infections.

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Capsule of a Lymph Node

The outer connective tissue layer of a lymph node that encapsulates the organ and provides structural support.

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Nodules in the Lymph Node

Clusters of B cells found in the outer cortex of a lymph node, where they multiply and differentiate into plasma cells to produce antibodies.

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Afferent Lymphatic Vessels

Vessels that carry lymph fluid into a lymph node, delivering it for filtering and immune surveillance.

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Efferent Lymphatic Vessels

Vessels that carry filtered lymph fluid out of a lymph node, returning it to the circulatory system.

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Innate Immunity

The first line of defense against foreign invaders, providing a rapid and non-specific response that is present from birth.

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Adaptive Immunity

The specific and targeted immune response that develops after exposure to a particular pathogen, involving memory and recognition of specific antigens.

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Phagocytosis

The process by which phagocytes engulf and destroy invading pathogens or cellular debris.

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Phagosome

A vesicle formed when a phagocyte's plasma membrane surrounds and encloses an engulfed pathogen.

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Phagolysosome

The structure formed when a phagosome fuses with a lysosome during phagocytosis.

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Oxidative Burst

A process during phagocytosis where reactive oxygen species are released to damage cellular molecules and kill the engulfed pathogen.

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Nonspecific Immunity

The body's initial defense against pathogens, reacting in the same way to any invader.

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Histamine

A chemical signal released by damaged tissue cells, causing vasodilation and increased vascular permeability.

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Vasodilation

Widening of blood vessels, increasing blood flow to the area.

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Vascular Permeability

Increased leakiness of blood vessels, allowing fluids and cells to pass through.

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Rolling

The process where leukocytes bind to endothelial cells and 'roll' along the surface, moving towards the site of damage.

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Emigration

Leukocytes squeezing through intercellular gaps in blood vessels and entering the tissue.

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Chemotaxis

Leukocytes following chemical trails to the site of tissue damage.

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Tissue Disinfection

Leukocytes performing their defensive roles (neutrophils phagocytize, NK cells kill) to clear invaders and damaged cells.

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Tissue Healing

The process of repairing damaged tissue after inflammation.

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Kinins

Proteins that promote vasodilation, increased vascular permeability, and leukocyte chemotaxis.

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Complement Proteins

Proteins that promote histamine release, attract neutrophils, and enhance phagocytosis.

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Lymphocyte Activation

When an antigen on an invader binds to antigen receptors on a lymphocyte, it triggers a process called lymphocyte activation.

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Effector Cells

A large population of lymphocytes produced during clonal selection that carry out the lymphocyte's defensive roles.

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Memory Cells

A smaller population of lymphocytes produced during clonal selection that remember the specific antigen.

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Exogenous Antigens

Foreign molecules circulating in bodily fluids that are processed and presented to lymphocytes.

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Antigen-Presenting Cell (APC)

A cell that processes and presents foreign antigens to lymphocytes.

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MHC-II

A molecule on antigen-presenting cells that binds to exogenous antigens and presents them to lymphocytes.

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Endogenous Antigens

Foreign antigens found inside body cells, such as viruses or tumor antigens.

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MHC-I

A molecule on all nucleated cells that binds to endogenous antigens and presents them to lymphocytes.

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CTL Activation

When TCRs on CTLs bind to endogenous foreign antigens presented by MHC-I, and CD8 protein interacts with MHC-I.

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Costimulation

A second signal required to fully activate T cells, often in the form of cytokines.

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CD8

A protein on CTLs that interacts with MHC-I, stabilizing the interaction between the CTL and the APC presenting the antigen.

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CTLs (Cytotoxic T Lymphocytes)

Lymphocytes that recognize and destroy infected cells through lysis and apoptosis.

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HTL Activation

When HTLs bind to exogenous foreign antigens presented by MHC-II on APCs, and CD4 protein interacts with MHC-II.

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CD4

A protein on HTLs that interacts with MHC-II, stabilizing the interaction between the HTL and the APC presenting the antigen.

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Plasma Cells

Effector B cells that produce antibodies.

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Vaccine

A harmless version of a foreign antigen designed to stimulate the immune system's primary response, priming it for a stronger and faster secondary response if exposed to the real antigen.

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Immunological Amnesia

Loss of immune system memory, specifically the ability to recognize and fight a particular pathogen due to the destruction of memory lymphocytes.

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Passive Immunity

Immune response where pre-made antibodies are transferred from one individual to another, providing temporary protection.

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Positive Selection

Process in the thymus where immature T cells that can bind to MHC-I molecules on cortical thymic epithelial cells are allowed to survive and continue development.

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Negative Selection

Process in the medulla of the thymus where T cells that strongly bind self-antigens are eliminated or inactivated, preventing autoimmune reactions.

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Autoimmunity

Immune system's failure to distinguish self from non-self, leading to attacks on the body's own tissues.

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HIV preferentially infects

Human immunodeficiency virus has a strong preference for CD4+ Helper T lymphocytes (HTLs), which are crucial cells for the immune system.

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Hypersensitivity

An exaggerated or inappropriate immune response to foreign antigens, often causing allergic reactions.

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Mast Cells degranulate

Mast cells release histamine and other inflammatory chemicals during an allergic reaction, contributing to symptoms like swelling and itching.

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Study Notes

Lymphatic System

  • The lymphatic system is the main organ system for defending against diseases and damage.
  • It consists of lymph, lymphatic vessels, and lymphatic organs.
  • Lymph is similar in composition to interstitial fluid and blood but richer in lipids after exiting the GI tract.
  • Lymph is filtered in lymphoid tissues and/or organs.
  • Lymphatic vessels begin as capillaries between cells that permit interstitial fluid to enter but not exit.
  • When interstitial fluid pressure is higher than inside the vessels, the fluid enters the lymphatic capillaries.
  • Specialized lymphatic capillaries in the small intestine (lacteals) absorb dietary lipids, forming chyle (creamy white lymph).
  • Lymphatic capillaries merge into lymphatic vessels, which carry lymph to lymph nodes and other lymphoid tissues for filtration.
  • Lymphatic vessels merge into lymph trunks that empty into lymphatic ducts (right and thoracic).
  • The right lymphatic duct drains lymph from the head, neck, and right upper limb into the right subclavian vein.
  • The thoracic duct, the largest lymphatic vessel, begins at the cisterna chyli and empties into the left subclavian vein.
  • The lymphatic system returns about 15% of filtered fluid (approximately 3 liters daily) to the circulatory system via skeletal muscle and respiratory pumps.

Lymphatic Organs and Tissues

  • Lymphatic organs are grouped into primary and secondary types.
  • Primary lymphatic organs are the red bone marrow and thymus.
  • Red bone marrow contains stem cells that give rise to blood cells, including lymphocytes.
  • The thymus is a bilobed gland where T lymphocytes mature.
  • The thymus cortex contains epithelial cells that train immature T cells, while the medulla contains mature T cells.
  • Secondary lymphatic organs include the spleen and lymph nodes, which contain immunocompetent cells.
  • The spleen is the largest mass of lymphatic tissue, filtering blood and removing worn-out cells.
  • Lymph nodes are bean-shaped organs that filter lymph and contain lymphoid nodules (clusters of B cells).
  • Lymphatic tissues lack a capsule, found in mucous membranes and Peyer's patches (aggregated lymphoid follicles).
  • Lymph nodes receive lymph via afferent vessels and release lymph through efferent vessels.

Immunity

  • Immunity is the body's resistance to damage or disease. Susceptibility is vulnerability to disease.
  • Pathogens are disease-causing microorganisms (bacteria, viruses, fungi, parasites).
  • Immunity is broadly divided into innate and adaptive immunity.
  • Innate immunity is nonspecific, fast, and found in all animals.
  • Adaptive immunity is specific, slower, and only found in vertebrates.

Innate Immunity

  • Innate immunity has external defenses (first line) and internal defenses (second line).
  • External defenses include:
    • Skin with keratin and acidic/salty environment.
    • Mucous membranes with mucus, cilia, tears (with lysozyme), and other fluids.
    • Antimicrobial substances (interferons, complement proteins, iron-binding proteins, AMPs).
  • Internal defenses include phagocytes (neutrophils, macrophages).
  • Phagocytosis process: chemotaxis, adherence, ingestion (phagosome formation), digestion (phagolysosome formation), and killing.
  • Inflammation: a nonspecific response to tissue damage, characterized by redness, swelling, heat, pain, and immobility.
  • Chemicals that cause inflammation: histamine, kinins, prostaglandins, leukotrienes, complement proteins.
  • Fever is an innate immune response that raises body temperature to combat infection.

Adaptive Immunity

  • Adaptive immunity uses lymphocytes (including cytotoxic t lymphocytes (CTLs) and helper t lymphocytes (HTLs)) with antigen receptors to recognize specific antigens.
  • Lymphocytes are clonally selected and produce effector and memory cells for long-term protection.
  • Antigens are processed and presented by antigen-presenting cells (APCs) to activate lymphocytes.
  • Exogenous antigens are processed by APCs using MHC-II.
  • Endogenous antigens are processed by APCs using MHC-I.
  • T cell activation requires costimulation using cytokines.
  • CTLs directly kill infected cells via perforins and granzymes.
  • HTLs activate other lymphocytes (e.g., B cells), producing antibodies to fight extracellular pathogens.
  • Antibodies are immunoglobulin proteins made by plasma cells, enhancing phagocytosis and promoting cell lysis.

Immunological Memory

  • First exposure to an antigen results in a primary immune response with slower antibody production.
  • Subsequent exposure to the same antigen triggers a faster and stronger secondary immune response due to memory lymphocytes.
  • Vaccines use harmless antigens to stimulate the primary immune response and create immunological memory.

Self-Recognition and Self-Tolerance

  • The immune system must distinguish between self and foreign cells.
  • Positive selection in the thymus ensures T cells can recognize self-MHC molecules.
  • Negative selection eliminates T cells that react to self-antigens to prevent autoimmunity.
  • Failure of self-tolerance can lead to autoimmune disorders.

Homeostatic Imbalances

  • Immunodeficiency diseases reduce immune system function.
  • Autoimmune disorders mistakenly attack self-antigens.
  • Hypersensitivities are excessive immune responses to harmless substances.
  • AIDS results from HIV infection preferentially targeting CD4+ HTLs, reducing the adaptive immune response.
  • Allergies are a type of hypersensitivity.

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Description

This quiz explores the components and functions of the lymphatic system. It covers aspects such as lymph composition, lymphatic vessels, and the role of lymph nodes in filtering lymph. Test your knowledge on this crucial organ system that protects against diseases.

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