Lymphatic System. Where s your immunity idol?

Transcription

1 Lymphatic System Where s your immunity idol?

2 Lymph Parts of the Lymphatic Lymphatic Vessels Lymphatic Tissue Lymphatic Organs System

3 Functions of the Lymphatic Fluid Balance System Drains excess fluid from tissues Lymph contains solutes from plasma Fat Absorption Lymphatic system absorbs fat from digestive system through lacteals Defense Lymph nodes help filter microorganisms from the body

4 Structure of Lymphatic Tissue

5 Lymphatic Vessels Capillaries more permeable than blood capillaries Have one way valves preventing lymph from passing back into the tissues Contraction of lymphatic vessels, skeletal muscle, and thoracic pressure changes move lymph through the vessels

6 Lymphatic Trunks Lymphatic vessels pass through lymph nodes then converge to lymphatic trunks Jugular Trunk drain head and neck Subclavian Trunk drain upper limbs, superficial thoracic wall and mammary glands Bronchomediastinal Trunk thoracic organs Intestinal Trunk abdominal organs Intercostal Trunk - ribs Lumbar Trunk lower limbs, pelvic organs, reproductive organs, kidneys and adrenal glands

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8 Lymphatic Ducts Lymphatic Trunks connect to lymphatic ducts or large veins Right lymphatic duct 20% people jugular, subclavian, bronchomediastinal trunks Thoracic duct drains lymph from right side of body inferior to thorax and entire left side of the body

9 Lymphatic Ducts

10 Structure of Lymphatic Tissue Contains reticular cells that make reticular fibers Contains lymphocytes (B and T cells) for immune response 2 types Encapsulated surrounded by connective tissue Thymus, Spleen and Lymph Nodes Diffuse Lymphatic Tissue

11 Diffuse Lymphatic Tissue No clear boundary; found as lymphatic nodules and within lymph nodes and spleen Contains lymphocytes, macrophages and other cells MALT mucosa associated lymphoid tissue nonencapsulated lymphatic tissue found under mucous membranes MALT include diffuse lymphatic tissue, lymphatic nodules, tonsils Lymphatic Nodules Spherical dense aggregates of lymphoid tissue with no distinct boundary between it and the surrounding tissue Not found along a lymphatic vessel Plentiful in digestive, urinary, respiratory, and reproductive systems Peyer s Patches lymphatic nodules of the distil small intestines and appendix *Lymphatic follicles parts of a nodule found in the spleen or in lymph nodes

12 Scattered along lymphatic vessels Filter bacteria or other material from the lymph Site of B cell & T cell activation 2 categories: superficial and deep Lymph Nodes

13 Tonsils Groups of lymphatic nodules and diffuse lymphatic tissue 3 groups of tonsils Palatine large oval shaped at oral cavity and pharynx junction Pharyngeal lymphatic nodule collection near nasal cavity and pharynx join Lingual lymphatic nodules on the posterior surface of the tongue

14 Spleen 2 Tissue Types White pulp lymphatic tissue surrounding arteries; composed of lymphocytes & macrophages Red pulp lymphatic tissue associated with veins; lots of erythrocytes Destroys defective RBCs Detects and responds to foreign materials Blood reservoir monitors blood volume

15 Thymus Decreases in size in late life Divided into irregular shaped lobules filled with lymphocytes (cortex) The medulla is composed of thymic corpuscles, rounded epithelial structures Lymphocyte production and T-cell maturation occur here Hormone Production Occurs

16 Lines of Defense First Defense External Barriers Acid Mantle, Defensins, Cathelicidins, Dermicidin, Lysozyme Second Defense Non-Specific Defense Leukocytes & Macrophages, Antimicrobial Proteins, Immune Surveillance & Fever Third Defense Immune System Defeat the Antigen & Make a Memory of It

17 Cells of the Immune System Neutrophils Small, phagocytic, first to infected area Respiratory Burst- absorbs O2 to create H 2 O 2 and HClO - Basophils motile WBC Produce leukotrienes to call and activate neutrophils & eosinophils Produce histamine to vasodilate Produce heparin, an anticoagulant Mast Cells nonmotile WBC in connective tissue Helps with inflammation response Eosinophils Clean up histamine and leukotrienes from basophils Fight worm parasites Reticular Cells stationary APCs Contribute to the framework of the lymphatic organs Monocyte Derived Cells- Macrophages- Enlarged monocytes Produce interferons, prostaglandins & complement to enhance immune response Produce heparin, an anticoagulant Dendritic Cells- Antigen Presenting Cells found in mucous membranes, skin, lymphatic organs Use receptor mediated endocytosis to dismantle and then display Ag

18 Cells of the Immune System T Cells- Various cell types that function in cell mediated immunity (adaptive) Helper T cells, Cytotoxic T cells, etc. B Cells- Can differentiate into plasma cells that produce antibodies Can differentiate into Memory Cells Natural Killer (NK) Cells Responsible for Immune Surveillance Recognize tumor cells or virus infected cells release chemicals to cause cells to lyse

19 Cells of the Immune System

20 Antigens (Ag) Molecules that trigger an immune response Venoms - Toxins Components of - Proteins Bacteria Cell Walls - Polysaccharides Components of - Glycoproteins Cell Membranes - Glycolipids Epitopes (antigenic determinants) regions of antigens that stimulate immune responses Haptens molecules too small to be antigenic, but bind to macromolecules and stimulate immune responses

21 Immunity Ability to resist damage from foreign substances, harmful chemicals, and internal threats 2 categories Innate Immunity or Nonspecific Resistance Body recognizes and destroys antigens response is always the same no matter what antigen is present Adaptive Immunity or Specific Immunity Two Types: Cellular (Cell-Mediated) & Humoral (Antibody-Mediated) Specificity recognizes and distinguishes between specific antigens Memory cells remember previous encounters Faster and sharper response

22 Innate Immunity Mechanical Mechanisms Prevent entry into the body or remove antigens from body surfaces Skin Mucous membranes Tears Saliva Urine Coughing Sneezing Ciliated tissues

23 Innate Immunity Chemical Mediators Found on cell surfaces to kill or prevent microorganism entry Promote inflammation Cytokines are secreted by cells to bind to cell surface receptors to regulate intensity and duration of immune response and stimulate the production of different cell types paracrine and autocrine function Examples of Cytokines: interferons, interleukins, lymphokines

24 Innate Immunity Chemical Mediators Interferons Proteins produced by viral infected cells that attach to neighboring cell surfaces stimulating the cells to produce antiviral proteins Activate NK cells

25 Innate Immunity Chemical Mediators Complement Group of 30+ proteins, named C1-C9 and factors B,D, and P Made mostly in the liver Circulate in inactive form, activation = the complement cascade & causes them to split into fragments (example: C3a & C3b) 3 ways to begin complement cascade Lectin pathway lectin binds to a carbohydrate found in a microbial cell surface leading to C3b production Alternative pathway C3 becomes active spontaneously producing C3b which splits more C3 Classical pathway requires an antibody (Specific Immunity) antigenantibody (Ag-Ab) complex causes change in antibody shape exposing complement binding sites, C1 binds to the site and many more complement proteins follow and bind. This is called complement fixation.

26 Innate Immunity Chemical Mediators Activated Complement Causes 1. Inflammation 2. Immune Clearance 3. Phagocytosis 4. Cytolysis

27 Inflammatory Response Symptoms: redness, heat, swelling, pain Functions: limit spread of antigens, destroy antigens, remove damaged tissue, initiate tissue repair Local inflammation confined to a specific area Symptoms: redness, heat, swelling, pain Systemic inflammation occurs in many parts of the body Symptoms: local symptoms, large amounts of neutrophils produced, fever, increased vasodilation

28 Inflammatory Response 1. Hyperemia increased blood flow 2. Fibrinogen walls off damaged area while heparin keeps the damaged area fluid-like 3. Neutrophil chemotaxis 4. Macrophages cleanup the area 5. Edema closes compresses veins to increase drainage of the area through lymphatic vessels

29 Innate Immunity Immune Surveillance Natural Killer Cells - Patrol for pathogens or infected host cells - Release proteins called perforins - Perforins create a hole in the antigen s cell membrane - Water and salts flood the antigen - Secrete granzymes - Granzymes enter the antigen and destroy cellular enzymes, inducing apoptosis

30 Innate Immunity Fever Fever or Pyrexia (Febrile) - Promotes interferon activity - Elevates metabolic rate and accelerates tissue repair - Inhibits bacterial and viral reproduction - Stages: onset, stadium, defervescence or crisis Exogenous Pyrogens substances from an antigen that induce a fever Endogenous Pyrogens substances from the body that induce a fever

31 Immunity Ability to resist damage from foreign substances, harmful chemicals, and internal threats 2 categories Innate Immunity or Nonspecific Resistance Body recognizes and destroys antigens response is always the same no matter what antigen is present Adaptive Immunity or Specific Immunity Two Types: Cellular (Cell-Mediated) & Humoral (Antibody-Mediated) Specificity recognizes and distinguishes between specific antigens Memory cells remember previous encounters Faster and sharper response

32 Antigen Presenting Cells (APCs) Recognize foreign antigens and present them for destruction Dendritic Cells - Macrophages/Monocytes Reticular Cells - B Cells Major Histocompatibility Complex (MHC) genes on chromosome 6 that code for MHC proteins - MHC proteins label you as you 1. APC engulfs antigen and digests it 2. Fragments of antigen are displayed in MHC proteins 3. T cells inspect the fragments presented

33 Lymphocyte Activation Major Histocompatability Complex Molecules MHC Class I Molecules Display antigens produced by the APC MHC Class I/antigen complex combine with T cells T cells destroy the infected cell MHC Class II Molecules Found on antigen presenting cells Display antigens on the surface of the cell T cells bind to the MHC Class II/antigen complex causes an alert signal to the immune system Antibodies are produced

34 Cytotoxic T Cells (Killer T Cells Tc) Lyse cells by using perforin & granzymes Attack & kill other cells that have Ag-MHCP complex Deliver a lethal hit of cytotoxic chemicals interferons & tumor necrosis factor Release cytokines to stimulate other immune response Helper T Cells (TH) Help Tc Cells Adaptive Immunity Cell Mediated Immunity Help in Humoral Immunity or Antibody-Mediated Immunity Help in Nonspecific or Innate Immunity

35 Adaptive Immunity Cell Mediated Immunity Regulatory T Cells (T-regs or TR) Limit Immune Response Inhibit T cell multiplication Inhibit cytokine production Memory T Cells (TM) Descendants from cytotoxic T cells Responsible for memory in cellular immunity

36 Adaptive Immunity Cell Mediated Immunity Lymphocytes directly attack & destroy foreign cells or diseased host cells Effective against intracellular microorganisms 1. APC processes an Ag & takes it to lymph node 2. APC presents Ag fragments in MHCP -MHC-I = Tc will attack if it is an Ag and will NOT if it is a self Ag -MHC-II (Human Leukocyte Antigens, HLAs) = TH cells respond and are always foreign antigens 3. T cell activation occurs when the T cell binds to a 2 nd APC protein (costimulation) 4. T cell undergoes mitosis (clonal selection); some become memory T cells and some carry out the attack on the Ag

37 Adaptive Immunity Cell Mediated Immunity 5. Helper T cell secrete interleukins 6. Cytotoxic T cells delivers the lethal hit 7. Some helper T cells and cytotoxic T cells become memory cells

38 T Cell Production

39 Adaptive Immunity Cell Mediated Immunity

40 Adaptive Immunity Antibody Mediated Immunity (Humoral Immunity) Humoral Immunity does not directly attack foreign cells. B cells produce antibodies (Ab) that bind to Ag and mark them for destruction. Stages of Humoral Immunity * Recognition * Attack * Memory

41 Adaptive Immunity Antibody Mediated Immunity (Humoral Immunity) Recognition- - B cells become active when it binds to several Ag - The cell takes in the Ag by endocytosis - B cell processes Ag and displays epitopes with MHC-II proteins - TH cell binds to Ag-MHCP complex & secretes interleukins - B cell is activated to clonal selection - Clones differentiate into plasma cells

42 Adaptive Immunity Antibody Mediated Immunity (Humoral Immunity) Antibody Structure Globulin proteins immunoglobulins (Ig) or gamma globulins Consists of 4 protein chains 2 light and 2 heavy Each has a variable region for specific antigens and a constant region Five classes IgG, IgM, IgA, IgE, IgD named for the C region (alpha, delta, epsilon, gamma, mu)

43 Antigenic Determinants or Epitopes Specific regions of antigens that are recognized by lymphocyte receptors

44 Adaptive Immunity Antibody Mediated Immunity (Humoral Immunity) Attack- 4 Mechanisms To Fight Antigens Neutralization- Ab mask active regions of Ag Complement Fixation- IgM or IgG bind to foreign cells, change shape to expose complement binding sites, complement (innate immunity) activated Agglutination- Ab have 2 to 10 binding sites; Ab will bind to more than one Ag clumping enemy cells together Precipitation- Ab link Ag together forming a complex too large and must be removed by immune clearance

45 Antibody Mediated Immunity

46 B Cell Production

47 Antibody Mediated Immunity Memory- Primary Response 1 st exposure of a B-cell to an antigen; results in cell differentiation and antibody production; 3-14 day response time IgM appears first & peaks in 10 days IgG levels rise & drop in 1 month Once stimulated, B-cell divides to form plasma cells and memory B cells

48 Antibody Mediated Immunity Secondary or Memory Response 2 nd exposure to an antigen; results in memory B cells dividing to produce plasma cells which make antibodies in large quantities; response time is hours to days Each exposure causes memory B cells to be produced Memory B cells can provide a defense for years to life

49 Acquired Immunity Active Natural Active Artificial Passive Natural Passive Artificial