immune system madeleine myers rn, ms, fnp. objectives list three functions of the lymphatic system....

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


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


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

Copyright © 2007 by Saunders, an imprint of

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.



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




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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




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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




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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




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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




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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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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




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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




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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)




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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




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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

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