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Immune System
Madeleine Myers RN, MS, FNP
Objectives
• List three functions of the lymphatic system.• Describe the composition and flow of lymph.• State the location of the following lymph
nodes: cervical nodes, axillary nodes, and inguinal nodes.
• Describe the four lymphoid organs: lymph nodes, tonsils, thymus gland, and spleen
• List three functions of the lymphatic system.• Describe the composition and flow of lymph.• State the location of the following lymph
nodes: cervical nodes, axillary nodes, and inguinal nodes.
• Describe the four lymphoid organs: lymph nodes, tonsils, thymus gland, and spleen
The Lymphatic System
• Main functions:– Return tissue fluid to the blood– Intestinal absorption of fats and fat-soluble
vitamins– Helps the body defend itself against disease
Functions of the Immune SystemFunctions of the Immune System
• To protect the entire body from a variety of harmful substances– pathogenic microorganisms– allergens– toxins– malignant cells
The Lymphatic System
Elephantiasis
Plasma
• plasma– 92% water– 8% plasma proteins
• albumin
• globulin
• fibrinogen
• serum - plasma without clotting proteins or fibrinogen
The Lymphatic System (cont’d.)
• Lymph: clear fluid that resembles plasma and is formed from plasma during capillary exchange
• Composition of lymph: water, electrolytes, waste from metabolizing cells, and some protein that leaks out of the capillaries of the systemic circulation
Structures of the Immune SystemStructures of the Immune System
• Unlike other body systems, Immune System is NOT contained within a single set of organs or vessels
• Action depends on structures from lymphatic, cardiovascular, and Integumentary systems
• Works primarily through antigen-antibody reaction
Lymphatic SystemLymphatic System
• Major structures– lymph vessels
– lymph nodes
– lymph fluid
– tonsils
• Also– spleen
– thymus
The Lymphatic SystemThe Lymphatic System
Lymph SystemLymph System
• Lymph originates in blood plasma
• Interstitial fluid• cleans and nourishes body
tissues• collects cellular debris,
bacteria• return to blood or lymph
capillaries
Lymph NodesLymph Nodes
• located in lymph vessels• small round or oval
structures (filters)• depositories for cellular
debris• bacteria and debris
phagocytized
Lymph NodesLymph Nodes
• inside are masses of tissue which contain WBCs (lymphocytes)
• almost always grouped 2 or 3 to 100
• invading cells destroyed in nodes and often swell as an indicator of the disease process
SpleenSpleen
• sac-like mass of lymphatic tissue
• filter for lymph• phagocytic cells• hemolytic
ThymusThymus
• lymphatic tissue
• mediastinum
• primary role: changes lymphocytes to T cells for cellular immunity
TonsilsTonsils
• masses of lymph tissue designed to filter tissue fluid, not lymph
• located beneath certain areas of moist epithelium exposed to outside and hence to contamination
• any or all may become so loaded with bacteria that the pathogens gain dominance
• should not be removed unless absolutely necessary.
Antigen-Antibody ReactionsAntigen-Antibody Reactions
• Antigen - any substance that the body regards as foreign (virus, bacterium, toxin)
• Antibody - a disease fighting protein developed by the body in response to the presence of an antigen
• Antigen-antibody reaction or immune reaction
Web pages• Inflamatory response• http://www.sumanasinc.com/webcontent/animations/c
ontent/inflammatory.html• HIV • http://www.sumanasinc.com/webcontent/animations/content/lif
ecyclehiv.html
• aninmations• http://outreach.mcb.harvard.edu/animations_S04.htm• Movie• http://www.rockefeller.edu/interactive/movies/dcell.ht
ml
Rewiew
Functions of the Lymph SystemFunctions of the Lymph System
• lymph/o• drain fluid from tissue spaces and return to
it to the blood• transport materials (nutrients, hormones and
oxygen) to body cells• carry away waste products to the blood • transport lipids away from digestive system• control of infection
Lymphoid OrgansLymphoid Organs
The Lymphatic System
Lymph capillaries and blood capillaries.
The Lymphatic System (cont’d.)
• Lymphatic vessels: includes lymphatic capillaries and several larger lymphatic vessels; “run with” the veins
Lymphoid Organs
• Organs:– Lymph nodes
– Tonsils
– Thymus gland
– Spleen
• Functions:– Filter particles from lymph, tissue fluid, and blood
– Support activities of lymphocytes
• Organs:– Lymph nodes
– Tonsils
– Thymus gland
– Spleen
• Functions:– Filter particles from lymph, tissue fluid, and blood
– Support activities of lymphocytes
Immune System
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Elsevier Inc.All rights reserved.
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Lesson 21.1 Objectives
• Differentiate between specific and nonspecific immunity.
• Describe the process of phagocytosis.• Explain the causes of the signs of inflammation.• Explain the role of fever in fighting infection.• Explain the role of T cells in cell-mediated
immunity.
Lesson 21.1 Objectives (cont’d.)
• Explain the role of B cells in antibody-mediated immunity.
• Differentiate between genetic immunity and acquired immunity.
• Describe naturally and artificially acquired active and passive immunity.
• Identify the steps in the development of anaphylaxis.
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Elsevier Inc.All rights reserved.
Classification of theImmune System
• Immunology: study of the immune system
• Immunity: elaborate defense system of the human body– Nonspecific immunity: protects the body
against many different types of foreign agents– Specific immunity: hones in on a foreign
substance and provides protection against one specific substance but no others
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Classification of theImmune System (cont’d.)
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Classification of the Immune System (cont’d.)
• Nonspecific immunity: – First line of defense– Second line of defense
• Specific immunity:– Third line of defense
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Nonspecific Immunity
• First line of defense: – Mechanical barriers– Chemical barriers– Certain reflexes
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Nonspecific Immunity (cont’d.)
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• Second line of defense– Phagocytosis– Inflammation– Fever– Protective proteins– Natural killer cells
Nonspecific Immunity (cont’d.)
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• Phagocytosis: – Phagocyte’s plasma membrane sends out
pseudopods to surround pathogen– Pathogen is captured when pseudopods fuse– Lysosomal membrane fuses with pathogen– Potent enzymes are released to destroy
pathogen
Nonspecific Immunity (cont’d.)
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• Inflammation: responses the body makes when confronted by an irritant– Signs of inflammation: redness, heat, swelling, pain– Infection: inflammation caused by pathogenic irritant– Histamine: released by cells when tissues are injured or
irritated– Pus: thick, yellowish accumulation of dead leukocytes,
pathogens, injured cells, and tissue fluid
Nonspecific Immunity (cont’d.)
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• Fever: abnormal elevation in body temperature– Pyrogens: fever-producing substances released by
phagocytes; stimulate the hypothalamus to reset the body’s temperature and produce a fever
Nonspecific Immunity (cont’d.)
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• Protective proteins: – Interferons: group of proteins secreted by cells
infected by a virus– Complement proteins: attach to outer membrane of
bacterium to fill it with fluid and electrolytes, causing lysis; enhance phagocytosis and inflammatory response
• Natural killer (NK) cells: special types of lymphocytes that act nonspecifically to kill various cells
Nonspecific Immunity (cont’d.)
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• Third line of defense:– Lymphocytes
• T lymphocytes
• B lymphocytes
– Macrophages
• Antigen: substance that stimulates the formation of antibodies
Specific Immunity
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Specific Immunity (cont’d.)
• Lymphocytes:– T lymphocytes (T cells):
• Thymus-derived lymphocytes
• Live and work in lymphoid tissue and circulatein blood
• Comprise 70% to 80% of the blood’s lymphocytes
• Attack antigens directly through cell-to-cell contact, or cell-mediated immunity
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Specific Immunity (cont’d.)
Cell-mediated immunity.
Cell-mediated immunity.
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• T cells: cell-mediated immunity– Killer T cells: punch holes in pathogen’s cell membrane
and secrete lymphokines that enhance phagocytic activity– Helper T cells: secrete a lymphokine that stimulates T
cells and B cells and enhances immune response– Suppressor T cells: inhibit immune response when the
antigen has been destroyed– Memory T cells: remember the initial encounter with an
antigen and quickly reproduce and allow a faster immune response in subsequent encounters
Specific Immunity (cont’d.)
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• Lymphocytes:– B lymphocytes (B cells):
• Liver and bone marrow-derived lymphocytes
• Live and work in lymphoid tissue and circulate in blood
• Comprise 20% to 30% of the blood’s lymphocytes
• Interact with antigens indirectly through the secretion of antibodies, or antibody-mediated immunity
Specific Immunity (cont’d.)
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Specific Immunity (cont’d.)
Antibody-mediated immunity.
Antibody-mediated immunity.
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• B cells: antibody-mediated immunity– Immunoglobulins: antibodies secreted by B cells
found in the gamma globulin part of plasma proteins
– Three most abundant types of immunoglobulin:• Immunoglobulin G (IgG)
• Immunoglobulin A (IgA)
• Immunoglobulin M (IgM)
Specific Immunity (cont’d.)
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• Antigen-antibody reaction: antibodies bind to antigens and react with antigens directly
• Agglutination: the clumping together of the antigen-antibody components
• Activated complement proteins: stimulate chemotaxis, promote agglutination, make pathogens more susceptible to phagocytosis, and encourage lysis
Specific Immunity (cont’d.)
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Specific Immunity (cont’d.)
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Types of Immunity
• Two main categories of immunity:– Genetic immunity: genetic information
conveys immunity to certain diseases
– Acquired immunity: received during person’s lifetime, either naturally or artificially
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Types of Immunity (cont’d.)
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Acquired Immunity
• Naturally acquired immunity– Active immunity: antibodies and memory cells
are produced in the body after first exposure to a specific pathogen
– Passive immunity: antibodies that were developed in response to the pathogens the mother encountered in her life are passed to a fetus by the mother
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• Artificially acquired immunity– Active immunity:
• Vaccine: antigen-bearing substance injected into a person to stimulate antibody production
– Passive immunity:• Immune globulin: obtained from a donor that has
developed the antibodies in response to a specific antigen
Acquired Immunity (cont’d.)
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Other Immunologic Responses
• Allergic reactions: immune system forms antibodies to substances not usually recognized as foreign– Delayed-reaction allergy– Immediate hypersensitivity reaction
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Other Immunologic Responses (cont’d.)
Immediate reaction allergy.
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Other Immunologic Responses (cont’d.)
• Autoimmune diseases: develop in response to self attack, or autoimmunity
• Organ rejection: recipient’s immune system recognizes donated organ as foreign and mounts an immune attack against it
Review
WBCs for Immune ReactionsWBCs for Immune Reactions
• monocytes - type of lymphocytes – formed in bone marrow/transported where needed by
body– become macrophages
• macrophage - phagocytic cell that protects body by ingesting invading cells
• lymphocytes - major class of WBCs– formed in lymphatic tissue
Lymphocytes
• T cells or T Lymphocytes– mature in thymus gland– Cell mediated immunity
• B cells or B Lymphocytes– mature in bone marrow– antibody-mediated
immunity
T Cell or T Lymphocyte(Cell Mediated Immunity)
T Cell or T Lymphocyte(Cell Mediated Immunity)
• T Cell (cell mediated immunity)– circulating lymphocytes– produced in bone marrow– matures in thymus– live for years– primary function: coordinate immune defenses and kill
organisms
Lymphocyte: T CellsLymphocyte: T Cells
• helper T cells - essential to proper functioning of immune system
• Memory cells- remember antigens and stimulate a faster response if same antigen introduced at a later time
ImmunityImmunity
• Immunity-state of being resistant or not susceptible to a specific disease
• Acquired immunity-any form of immunity NOT present at birth and obtained during life
Factors That Influence Immune System
Factors That Influence Immune System
• Health
• Age
• Heredity
Acquired Immune Deficiency Syndrome (AIDS)
Acquired Immune Deficiency Syndrome (AIDS)
• Caused by HIV (Human Immunodeficiency Virus)
• HIV infects T-helper cells with often a long incubation of up to 10 years
• AIDS name applied during advanced stages of disease
• After immune system destroyed, opportunistic infections occur.
Autoimmune DisordersAutoimmune Disorders
Antigens stimulate development of antibodies that are unable to distinguish antigens of internal cells.
Body makes antibodies and T cells against itself and attacks own tissues.
Multisystemic involvement.
Myasthenia gravis, rheumatoid arthritis
Infectious MononucleosisInfectious Mononucleosis
• Acute infection caused by virus.
• Fever, sore throat, swollen lymph glands, atypical lymphocytes, splenomegaly, hepatomegaly, abnormal liver function, and bruising.
• transmitted by droplet infection
• Infection confers permanent immunity
• Treatment symptomatic
Web sites
• Specific immunity
• http://science.nhmccd.edu/biol/inflam.html