Presentation on theme: "System which launches fight against infections"— Presentation transcript:
1System which launches fight against infections The Lymphatic SystemSystem which launches fight against infections
2Lymphatic SystemThe major components of the lymphatic system are lymphatic vessels, lymph, lymph nodes, and some other lymphatic organsLymphatic vessels carry lymph, a colorless liquid, throughout the body. Along lymph vessels are small bean-shaped glandular nodules called lymph nodes.Other lymphatic organs are:Tonsil: clusters of lymphatic tissues just under the mucous membranes that line the nose, mouth, and pharynx.Spleen: it is similar to a lymph node in shape and structure but it is much larger.Thymus: a soft organ with two lobes that is locatedanterior to the ascending aorta and posterior to the sternum.Peyer patch: lymphoid tissue on the visceral surface of the small intestine.
3Lymphatic System Primary Lymphoid Organs Secondary Lymphoid Organs Bone marrow and ThymusSecondary Lymphoid OrgansSpleen, tonsils, Peyer’s patchesLymphatic system, upper respiratory system and muscular system ALL contain lymphatic vessels
4Lymphatic VesselsLymphatic vessels carry excess fluid from tissues and return it to the bloodstream.Have flaplike valves that help prevent backflow of lymphVessels lead to lymph nodesAfter leaving the nodes, the vessels merge to form lymphatic trunks
5Lymphatic Capillaries Thinned walled capillaries which allow fluid to enter.Fluid inside is called “lymph”Lacteals: lymphatic capillaries located in lining of small intestines which absorb fat and transport them to venous circulation
6Lymph nodes and ductsThe right lymphatic duct drains lymph from the upper R side, whereas the thoracic duct drains lymph from the rest of the body.Lymphatic capillaryLymphatic vesselLymph nodeLymphatic trunkCollecting ductSubclavian vein
7Lymph nodes Glands which are located along the lymphatic pathways Contain large #s of lymphocytes and macrophagesLocated in neck, thoracic cavity, armpit (axillary), abdomen, pelvic area, inguinal area and supratrochlear nodes (where is this???)2 functions: filtration and providing lymphocytes and macrophages for immunityDo not trap wbcs but they do trap bacteria, and toxins
8The body’s defense system ImmunologyThe body’s defense system
9TerminologyImmunology: the study of how body components respond and interactImmunoglobulins: class of proteins that make up antibodiesPhagocytosis: process where cells engulf and destroy foreign particles such microorganisms or damaged cells. Macrophages and segmented neutrophils are the most important phagocytic cells
10TerminologyImmunogenicity: the degree to which an antigen elicits an immune responseImmunogen: antigen that stimulates an immune responseSoluble antigen: free floating antigen recognized by B cell receptors
11TerminologyEpitope: the small piece of an antigen that is bound by an antibody or a T cell receptorChemotaxis: release of substances which attract phagocytic wbc to bacteria. Cells move from an area of low to high concentration of chemokines.
12Immune SystemImmune System: cells in our bone marrow, thymus, and the lymphatic system of ducts and nodes, spleen, and blood that function to protect us.Function is to recognize self from nonself and to defend the body against nonself.
13Lines of Defense 1st line of Defense Non Specific Responses Innate or inbornGeneral response which protects us dailyNon Specific ResponsesInflammationPhagocytosisPhysical barriersChemical barriers
14Immune System 1st line of defense: Skin and mucosal membrane surfaces Secretions: mucous on membranes in nose trap microorganisms and are secreted through sneezing. What other secretions can you think of?Tears, saliva, ear wax, sweat, production and elimination of urinePhagocytic wbc in the mucous membrane
15Immune System 1st line of defense continued: Normal flora deter penetration of microorganismspH of body fluids such as gastric juicesCilia movement helps protect the respiratory tractThe enzyme lysozyme which is found in tears and saliva attacks and destroys the cell wall of susceptible bacteria especially some gram positive bacteria
16Immune System Non specific cellular and chemical response Fever production resulting from pyrogenic secretions from pathogensInterleukin 1 produced resulting from stimulated macrophages.Polypeptide secreted by macrophages, enhance T cell activation and activityPhagocytosis: process of surrounding and engulfing foreign matter.Antibodies coating an invading microbe for phagocytosis is called opsonization.
17Activation of the Complement System Activation of complement proteinsOpsonization: enhancing phagocytosis of AgsChemotaxis: attracting macrophages and neutrophilsLysis: rupturing membranes of foreign cellsClumping of Ag bearing agentsAltering the molecular structure of viruses
18Inflammatory Response Involves granulocytes such as basophils and eosinophils.Mast cells are activated during an allergic reaction and release histamineDelayed hypersensitivity is also called Cell Mediated response
19Immune Responses 2nd line of Defense Specific Responses Specific Production of Abs in response to AgSpecific ResponsesAssociated with Ag and Ab reactionAb response occurs after exposure to AgAb may neutralize, kill, or cause clumping of foreign microorganismsComplement system also works w/Abs to destroy the invaderComplement system is a group of proteins produced in the liver, circulating in the plasma and enhance the work of Abs
20Types of Immunity Types of Immunity Example Active natural immunity Having a disease like the mumpsActive artificial immunityReceiving a vaccination like (MMR)Passive natural immunityAbs produced by the body itself or received from momPassive artificial immunityInjection of antibodies
21Natural Immunity Also known as innate (inherited) immunity Mechanism which kicks in after bacteria gets past the first lines of defenseNatural immunity is a non specific mechanism
22Natural Immunity Components of Natural Immune System Cellular componentsMast cellsNeutrophils: most abundant and 1st to arriveMacrophagesHumoral (fluid)ComplementLysozymeInterferon
23Leukocytes Type Function Polymorphonuclear (granulocytes) Phagocytosis NeutrophilsPhagocytosis, most active and voraciousEosinophilsAllergic responseBasophilsRelease histamine (so do mast cells)MonocytesBecome macrophages and phagocytesMacrophagesLymphocytesT LymphocytesCell mediated immunityB LymphocytesHumoral immunityPlasma cellsAntibody production
24Effector CellsPlasma cells: derived from lymphocytes (white blood cells) and are the cells which secrete antibodies. They live a short time and are constantly being replaced.Macrophages: derived from monocytes (wbc) w/primary function of phagocytosis
25Adaptive Immunity Also known as acquired immunity Active immunity can leave the host w/specific immunologic memory which allows the host to respond more effectively if re-infection with the same microorganism occurs
26Specific Immune Response Primary Immune Response: 10 to 17 days after initial exposure to Ag. Selected lymphocytes generate a maximum effector cell response.While effector cells are developing an infected person may become ill but eventually the symptoms of the illness disappear as Abs and effector T cells clear antigens from the body.Secondary Immune Response: later exposure to the Ag that results in a much faster (2-7 days), much faster, and more prolonged response by Abs and effector T cells
27Immunoglobulin Structure Composed of glycoproteins4 protein chains held together w/ disulfide bondsFc region: constant region dictates the type of immunoglobulin A, E, D, M, or GFab portion: antigen binding region of the Ab. This region is highly diverse so that the variety of antigens recognized by these receptors is extremely numerousHeavy chainsLight chains
28Immunoglobulin Structure Composed of 2 identicalHeavy chains and 2identical light chainsConstant regions are located on both the light and heavy chainsThe very end of the variable Regions is called the hypervariable as that is the region where the amino acid sequencing varies the most
29Antibodies Variable region is what determines the antigen specificity The constant region (Fc) is what determines the antibody immunological class or isotype (A,E,M,G, D)Antibodies do not destroy antigens directlyNeutralizeTarget for eliminationAgglutination, precipitation, complement fixation
30AntibodiesIgM: first type of antibody secreted during a primary immune response (promotes agglutination or clotting)IgG: major type of antibody secreted during a secondary immune responseIgE: type most associated with allergic reactions (promotes release of histamine)Students need to know these facts
31AntibodiesIgA: this is the antibody found in most abundance in bodily secretions such as saliva and mother’s milkIgD: this antibody serves as a B cell surface receptor.Soluble antibodies are involved in the followingCause clottingCan bind active sites on toxinsTag foreign microbes for destructionsBe sure students know these facts!
32Antibodies IgM and IgD are the first antibodies expressed by a B cell Each B cell has ~ 100,000 IgM or IgD receptors on its surfaceThese antibodies can bind free Ags whereas T cell receptors can only bind to Abs when they are presented by Ag presenting cells (discussed later)IgM and or IgD serve as B cell surface receptors so anytime you hear B cell receptor your first thought should be IgM and or IgD
33AntibodiesBinding the IgM or IgD on the B cell surface provokes a primary immune response resulting in secretion of IgM, B cell division, and clonal expansionSecretion of the IgM Abs stimulates the activation of the complement systemIgG Abs are then produced and promote phagocytosisClonal expansion: an activated B cell makes multiple exact duplicates (clones) that recognize the Ag that is bound and thus stimulated the activation of the original B cellIgM production triggers the complement system activationIgG production triggers phagocytosis
35B Cell Maturation Stem cell Pro- B cell Pre B cell Immature B cell mature B cellDuring this time of development the Ab/Ag specificity is being determined through a process of random genetic recombination. Also undergoes a process of negative selection to screen for self versus non self molecules. During the immature B cell stage: if the antigen receptor matches with a self antigen the cell dies by apoptosis called Clonal Deletion
36B Cell Maturation and Function When antigen binds to the B cell receptor, the B cell is activated and begins to undergo clonal expansion, which results in the proliferation of exact duplicates of the original B cell.When B cells are mature the must undergo a process to determine self tolerance. This process is Ag dependent.
37Humoral Immunity Summary Involves the production of Abs that circulate in the blood and lymph to defend against free bacteria, toxin, and virusesInvolves B cells that eventually differentiate into plasma cells or memory cellsAlso requires the use of Helper T cells and certain cytokines such as IL-2Plasma cells produce antibodies while memory cells wait for re-exposureAntibodies tag foreign microbes for destruction through several processesB cells mature and produce plasma cells (short lived) and memory cells (long lived)
38Cell Mediated Response Overview Involves direct killing of infected cells via TC cellsDoes not involve the production of AbsRequires both the activation of TH cells and TC cellsSome cells will become effector cells and some cells will become memory cells to wait for re-exposureMost important cell is the TH cellOverlaps with Humoral Response
39T Lymphocytes Originate in the bone marrow but mature in the thymus Stored in the secondary lymphatic tissueBasis for Cell Mediated immunityLifespan: resting 1-3 weeks, activated 3-4 days, memory years/lifetimeRespond to specific Ag and cancer cellsDo not produce Abs2 Primary types: cytotoxic and helper T cells
40T Cell Maturation Stem Cell Pro T cell Pre T cell Double positive T cell Double positive alpha beta TCR T cell Single positive T alpha beta TCR cellDuring this time of development T cell receptor (TCR) specificity is being determinedUndergoes process of both positive and negative screening for productive gene arrangement, self versus non-self molecules, and appropriate CD surface protein moleculesCD 8 = Cytotoxic T cell, CD 4 = Helper T cell
41Stem Cell differentiation Stem cells originate in the bone marrow
42Antigens Elicit an immune response 2 general types exist Exogenous: foreign from outside the hostEndogenous: foreign from within the hostViruses, bacteria, fungi, protozoa, and parasites are all antigensAntigenic determinants = epitope
43AntigensChemical composition are proteins and large polysaccharides (carbs)Proteins make the best immunogens due to their high MW and structural complexityPolysaccharides (carbs or sugars) are OK immunogens but their small size make them less effective than proteins
44AntigensLipids are inferior antigens because of their relative simplicity and lack of structural stabilityNucleic acids are poor Ag due to lack of molecular flexibility and rapid degradation
45Antigen ReceptorsThe way that B cells and T cells recognize specific molecules and trigger an immune responsePlasma membrane boundAll antigen receptors on a B cell or T cell have the same specificityDetermined by random genetic eventsOccurs before any contact w/foreign antigen is madeAllows for an enormous variety of B and T lymphocytes
46AutoimmunityImmune system fails to distinguish self from non self producing autoantibodies and cytotoxic T cells that attack and damage the body’s tissuesMay be caused by a virus replicating within a host cell or faulty T cells or antigen which closely resembles self Ag (example strep infection in heart valves)
47Autoimmunity diseases and conditions Cancer of the lymph nodes: when lymphocytes undergo a mutation and multiply out of controlRheumatoid arthritis: involves the joints, RF factor is test methodGrave’s disease: hyperthyroidism, affects young women, goiter is common side effect as well as exophthalmos (protrusion of the eyes)Pernicious anemia: mucous lining of stomach does not secrete protein called intrinsic factor which is needed for B12 absorption resulting in anemiaHIV infection: reverse transcription coverts viral RNA into DNA