Download Chapter 17

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




Merge to form larger & larger vessels


Lymphocytes in capsuled structure
 thoracic duct  L subclavian vein


Thin walled and more valves than veins
Periodically have lymph nodes


Slightly larger than blood capillaries
Overlapping cells like one-way valve
Pressure will force fluid in
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


Mucous membranes


Sticky mucus layer straps microbes, etc. and cilia
move it out
Fluids: tears, saliva, perspiration, nasal
secretions


Epidermal structure & constant shedding
Dilute and antibacterial action
Movement: flow of urine, defecation &
vomiting
Copyright 2010, John Wiley & Sons, Inc.
Internal Defenses: Proteins

Interferons


Complement System






Interfere with viral reproduction in a cell
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



Antibody-mediated
B cells become plasma cells


Killer T-cells
Produce specific antibodies
Helper T cells aid both cell- and antibodymediated 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



Binding both  response
T-cell begins rapidly dividing


Interleukin-2 (IL-2)
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



Immobilizing bacteria
Agglutinating



Binds and neutralizes toxins
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.
Copyright 2010, John Wiley & Sons, Inc.