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

Copyright 2010, John Wiley & Sons, Inc.

Chapter 17

The Lymphatic System and Immunity


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


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


Lymphatic System


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


Lymphatic Vessels


Lymphatic Vessels


Lymphatic Flow From tissue to veins Pumped by muscle & respiratory pumps like

venous return


Lymphatic Flow


Lymphatic FlowInteractions Animation

Lymph Formation and Flow

You must be connected to the internet to run this animation.


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


Thymus Two lobed organ Posterior to sternum, medial to lungs &

superior to heart T-cells divide & mature

Self reactive cells are removed


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


Lymph Nodes


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


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


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


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


Inflammation Response to tissue damage

Indicated by redness, pain, heat & swelling


Inflammation1. 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


Inflammation


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


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


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


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


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


Antigens & Antibodies


Antigens & Antibodies


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


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


Processing & Presenting Antigens


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


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


Cell Mediated Immunity


Cell Mediated Immunity


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


Secretion of Antibodies


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


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


Immunological MemoryInteractions Animation

Introduction to Disease Resistance

You must be connected to the internet to run this animation.


Aging Thymus atrophies Fewer responsive T cells Thus poorer B cell response Poorer response to new infection


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.

Documents

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