Transcript Human Anatomy & Physiology II

Chapter 17
The Lymphatic
System and Immunity
Copyright 2010, John Wiley & Sons, Inc.
Lymphatic Flow
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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
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Lymph Formation and Flow
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Copyright 2010, John Wiley & Sons, Inc.
Lymphatic Organs
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Primary lymphatic organs- stem cells divide &
develop into mature B & T-cells
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Red bone marrow & thymus
Secondary organs: immune responses occur
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Lymph nodes, spleen & lymphatic nodules
Copyright 2010, John Wiley & Sons, Inc.
Thymus
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Two lobed organ
Posterior to sternum, medial to lungs &
superior to heart
T-cells divide & mature
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Self reactive cells are removed
Copyright 2010, John Wiley & Sons, Inc.
Lymph Nodes
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Scattered throughout the body
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Concentrated near mammary glands, axilla &
groin
Contain mature B-cells, T-cells dendritic cells
and macrophages
Filter lymph, trap foreign substances
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Macrophages & lymphocytes destroy most foreign
substances
Copyright 2010, John Wiley & Sons, Inc.
Lymph Nodes
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Spleen
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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
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Inflammation
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Response to tissue damage
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Indicated by redness, pain, heat & swelling
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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
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Neutrophils & macrophages eat & die
4. Pocket of dead cells = pus
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Moves to body surface or into cavity & is cleared
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Inflammation
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Fever
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Abnormally high body temperature
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New set-point of thermoregulation system
Normal temperature control action with new set
point
Stimulated by many toxins or internal signals
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Interleukin-1
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Maturation of T and B cells
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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
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Cell-mediated- T-cells attack directly
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Antibody-mediated
B cells become plasma cells
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Killer T-cells
Produce specific antibodies
Helper T cells aid both cell- and antibodymediated responses
Copyright 2010, John Wiley & Sons, Inc.
Antigens & Antibodies
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Major Histocompatability Complex (MHC) = self
antigens on cells surface
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Unique to each individual
Allows T-cells to recognize foreign material
Antigen triggers plasma cell to produce antibodies
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Y-shaped protein with variable antigen binding site on
arms
Other end triggers recognition by phagocyte
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Triggering Adaptive Response
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Requires recognizing the foreign antigen
B-cells 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
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APC’s ingest & digest into fragments in
vesicles
Synthesize MHC & pack in vesicles
Two vesicles fuse
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Antigen fragments bind to MHC
Antigen-MHC complex inserted into plasma
membrane
Presented to T-cells until a receptor matches
& binds
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Processing & Presenting Antigens
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Cell Mediated Immunity
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T-ceils also need costimulator
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Binding both  response
T-cell begins rapidly dividing
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Interleukin-2 (IL-2)
Forms a clone of many recognizing cells
Helper T cells
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Release IL2, attract phagocytes, stimulate
macrophages & B cells
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Cell Mediated Immunity
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Cytotoxic T cells – kill cells
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Work against tumor cells transplanted cells &
infected cells
Memory T cells- hang around for years, give
rapid response
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B-cells and Antibody-Mediated Response
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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
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Ready to respond quickly if antigen met again
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Antibody Class Actions
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Neutralizing antigen
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Immobilizing bacteria
Agglutinating
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Binds and neutralizes toxins
Connect pathogens to one another  easier
phagocytosis
Activating complement
Enhancing phagocytosis
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Binding attracts phagocytes
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Immunological Memory
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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
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Killed cells, isolated antigens, parts of viruses
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Immunological Memory
Interactions Animation
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Introduction to Disease Resistance
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Aging
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Thymus atrophies
Fewer responsive T cells
Thus poorer B cell response
Poorer response to new infection
Copyright 2010, John Wiley & Sons, Inc.