Copyright 2010, John Wiley & Sons, Inc. Chapter 17 The Lymphatic System and Immunity

Copyright 2010, John Wiley & Sons, Inc. Immunity Innate Immunity Fast, non-specific and no memory  Barriers, pH extremes, Phagocytes & NK cells, fever, inflammation, complement, interferon Adaptive Immunity Slower, specific & has a memory  Lymphocytes: T-cells & B-cells

Copyright 2010, John Wiley & Sons, Inc. Lymphatic System Lymphatic tissue  Reticular connective tissue containing lymphocytes Bone marrow Lymph- interstitial fluid in lymphatic vessels Returns excess filtration from capillaries- to circulation Transport dietary lipids Maintenance & distribution- lymphoid organs Filter bacteria and help active defenses

Copyright 2010, John Wiley & Sons, Inc. Lymphatic System

Copyright 2010, John Wiley & Sons, Inc. Lymphatic Vessels Begin at lymphatic capillaries  Slightly larger than blood capillaries  Overlapping cells like one-way valve  Pressure will force fluid in Merge to form larger & larger vessels  Thin walled and more valves than veins Periodically have lymph nodes  Lymphocytes in capsuled structure  thoracic duct  L subclavian vein  At junction with jugular  R. lymphatic duct  R. subclavian vein

Copyright 2010, John Wiley & Sons, Inc. Lymphatic Vessels

Copyright 2010, John Wiley & Sons, Inc. Lymphatic Vessels

Copyright 2010, John Wiley & Sons, Inc. Lymphatic Flow From tissue to veins Pumped by muscle & respiratory pumps like venous return

Copyright 2010, John Wiley & Sons, Inc. Lymphatic Flow

Copyright 2010, John Wiley & Sons, Inc. Lymphatic Flow Interactions Animation Lymph Formation and Flow You must be connected to the internet to run this animation.

Copyright 2010, John Wiley & Sons, Inc. Lymphatic Organs Primary lymphatic organs- stem cells divide & develop into mature B & T-cells  Red bone marrow & thymus Secondary organs: immune responses occur  Lymph nodes, spleen & lymphatic nodules

Copyright 2010, John Wiley & Sons, Inc. Thymus Two lobed organ Posterior to sternum, medial to lungs & superior to heart T-cells divide & mature  Self reactive cells are removed

Copyright 2010, John Wiley & Sons, Inc. Lymph Nodes Scattered throughout the body  Concentrated near mammary glands, axilla & groin Contain mature B-cells, T-cells dendritic cells and macrophages Filter lymph, trap foreign substances  Macrophages & lymphocytes destroy most foreign substances

Copyright 2010, John Wiley & Sons, Inc. Lymph Nodes

Copyright 2010, John Wiley & Sons, Inc. Spleen Between stomach & diaphragm Contains blood filled venous sinuses and RBCs, macrophages, lymphocytes plasma cells & granular leukocytes destroys worn or defective blood cells & platelets Stores platelets attacks foreign substances in blood Fetal hemopoiesis

Copyright 2010, John Wiley & Sons, Inc. Innate Immunity: Barriers Skin: physical and chemical  Epidermal structure & constant shedding Mucous membranes  Sticky mucus layer straps microbes, etc. and cilia move it out Fluids: tears, saliva, perspiration, nasal secretions  Dilute and antibacterial action Movement: flow of urine, defecation & vomiting

Copyright 2010, John Wiley & Sons, Inc. Internal Defenses: Proteins Interferons  Interfere with viral reproduction in a cell Complement System  Enhance other immune actions  Break cell membranes  Attract phagocytes  Tag microbial cells for destruction Transferrins- bind iron and starve bacteria Antimicrobial peptides: lyse microbes

Copyright 2010, John Wiley & Sons, Inc. Internal Defenses: Cells Phagocytes specialized to ingest microbes and cellular debris  Neutrophils  Monocytes  macrophages 5-10% of lymphocytes = Natural Killer (NK) Cells  Destroy microbes & tumor cells  Present in lymph nodes & red bone marrow

Copyright 2010, John Wiley & Sons, Inc. Inflammation Response to tissue damage  Indicated by redness, pain, heat & swelling

Copyright 2010, John Wiley & Sons, Inc. Inflammation 1. Damage  mast cells, basophils & platelets release histamine  increased permeability & vasodilation in blood vessels 2. Leakage of clotting proteins into tissue-  Isolate bacteria behind clot 3. Phagocytes attracted to site  Neutrophils & macrophages eat & die 4. Pocket of dead cells = pus  Moves to body surface or into cavity & is cleared

Copyright 2010, John Wiley & Sons, Inc. Inflammation

Copyright 2010, John Wiley & Sons, Inc. Fever Abnormally high body temperature  New set-point of thermoregulation system  Normal temperature control action with new set point Stimulated by many toxins or internal signals  Interleukin-1

Copyright 2010, John Wiley & Sons, Inc. Adaptive Immunity Specifically directed against a particular type of invader Involves cell or antibody directed against a particular antigen  Antigen can be any substance: microbe, food, pollen, tissue Normally self–tolerant  Does not attack normal body tissue

Copyright 2010, John Wiley & Sons, Inc. Maturation of T and B cells From stem cells in red bone marrow B cells mature in bone marrow T cells migrate to thymus During maturation both make particular proteins in plasma membranes = antigen receptors

Copyright 2010, John Wiley & Sons, Inc. Types of Responses Cell-mediated- T-cells attack directly  Killer T-cells Antibody-mediated B cells become plasma cells  Produce specific antibodies Helper T cells aid both cell- and antibody- mediated responses

Copyright 2010, John Wiley & Sons, Inc. Antigens & Antibodies Major Histocompatability Complex (MHC) = self antigens on cells surface  Unique to each individual Allows T-cells to recognize foreign material Antigen triggers plasma cell to produce antibodies  Y-shaped protein with variable antigen binding site on arms  Other end triggers recognition by phagocyte

Copyright 2010, John Wiley & Sons, Inc. Antigens & Antibodies

Copyright 2010, John Wiley & Sons, Inc. Antigens & Antibodies

Copyright 2010, John Wiley & Sons, Inc. Triggering Adaptive Response Requires recognizing the foreign antigen B-ceils can find it anywhere T-cells need presentation with MHC Antigen presenting cells (APC) do this APCs macrophages, dendritic cells & B cells In respiratory, GI, urinary, reproductive tracts & lymph nodes

Copyright 2010, John Wiley & Sons, Inc. Processing & Presenting Antigens APC’s ingest & digest into fragments in vesicles Synthesize MHC & pack in vesicles Two vesicles fuse  Antigen fragments bind to MHC Antigen-MHC complex inserted into plasma membrane Presented to T-cells until a receptor matches & binds

Copyright 2010, John Wiley & Sons, Inc. Processing & Presenting Antigens

Copyright 2010, John Wiley & Sons, Inc. Cell Mediated Immunity T-ceils also need costimulator  Interleukin-2 (IL-2) Binding both  response T-cell begins rapidly dividing  Forms a clone of many recognizing cells Helper T cells  Release IL2, attract phagocytes, stimulate macrophages & B cells

Copyright 2010, John Wiley & Sons, Inc. Cell Mediated Immunity Cytotoxic T cells – kill cells  Work against tumor cells transplanted cells & infected cells Memory T cells- hang around for years, give rapid response

Copyright 2010, John Wiley & Sons, Inc. Cell Mediated Immunity

Copyright 2010, John Wiley & Sons, Inc. Cell Mediated Immunity

Copyright 2010, John Wiley & Sons, Inc. B-cells and Antibody-Mediated Response Hang out in lymph nodes Respond to antigen (faster if presented) With IL-2 enlarge, divide and become a clone of plasma cells Plasma cells produce & release antibodies that bind the antigen Some remain as Memory B Cells  Ready to respond quickly if antigen met again

Copyright 2010, John Wiley & Sons, Inc. Secretion of Antibodies

Copyright 2010, John Wiley & Sons, Inc. Antibody Class Actions Neutralizing antigen  Binds and neutralizes toxins Immobilizing bacteria Agglutinating  Connect pathogens to one another  easier phagocytosis Activating complement Enhancing phagocytosis  Binding attracts phagocytes

Copyright 2010, John Wiley & Sons, Inc. Immunological Memory Long lasting antibodies & lymphocytes Many sensitive memory cells  Much larger & quicker response next time = Secondary Response Primary response can be naturally acquired Or artificially acquired by vaccination  Killed cells, isolated antigens, parts of viruses

Copyright 2010, John Wiley & Sons, Inc. Immunological Memory Interactions Animation Introduction to Disease Resistance You must be connected to the internet to run this animation.

Copyright 2010, John Wiley & Sons, Inc. Aging Thymus atrophies Fewer responsive T cells Thus poorer B cell response Poorer response to new infection

Copyright 2010, John Wiley & Sons, Inc. End of Chapter 17 Copyright 2010 John Wiley & Sons, Inc. All rights reserved. Reproduction or translation of this work beyond that permitted in section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the Permission Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publishers assumes no responsibility for errors, omissions, or damages caused by the use of theses programs or from the use of the information herein.