The Body Defenses
Transcript of The Body Defenses
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The Body Defenses
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Body Defense Overview
Innate Immunity
Barrier Defenses
Internal Defenses
Acquired Immunity Humoral Response
Cell-mediated
Response
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Innate Immunity in Invertebrates
(Nonspecific) Chitin (physical
barrier) in intestine
Lysozymes and low
pH (digests microbialcell walls)
Hemocytes in
hemolymph
Phagocytosis
Antimicrobial peptides
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Innate Immunity in Vertebrates
Barrier Defenses (Nonspecific) Skin Physical Barrier &
Lysozymes
Digestive Tract High acidity & normal
bacteria
Respiratory Tract Mucus & Cilia
Genitourinary Tract
Acidity of Urine
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Innate Immunity in Vertebrates
Internal Defenses
(Nonspecific) Phagocytic White
Blood Cells The Inflammatory
Response
Antimicrobial
Proteins
Natural Killer Cells
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Phagocytic White Blood Cells
(Leukocytes) Neutrophils (70%)
short lived
Monocytes (5%) macrophages
long lived in lymphatic tissue
Eosinophils (1.5%) attack larger parasites
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The Inflammatory Response Releases histamine
(basophils and mast cells)
Allows for dilation and increased permeability
Increased temp due to increased blood flow
Cytokines (protein) direct migration ofPhagocytes (activate lymphocytes)
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Antimicrobial Proteins
Compliment System
30 proteins
lyses viruses and pathogens
may attract phagocytes and cause adherence Two pathways
Alternative
triggered by substances on invaders and does not use
antibodies
Classical
triggered by antigens and uses antibodies
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Antimicrobial Proteins
Interferon proteins secreted by viral infected cells
diffuse to surrounding cells
surrounding cells make chemicals that inhibit
viral reproduction
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Natural Killer Cells Recognize damaged or diseased cells
Class 1 MHC molecule on surface of most cells
Missing when diseased
Release chemical to destroy cells lacking this
protein
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Acquired Immunity
Vertebrates
Uses Lymphocytes to recognize antigens
Two major types
B lymphocytes
T lymphocytes
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Epitopes
Antigenic determinant (special areas on
antigens
Usually has several
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Antigen Recognition by
Lymphocytes
B Cells Y shaped receptors made up of
4 polypeptide chains (two heavy / two
light)
Recognize intact antigens
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Major Histocompatibility Complex
Class 1 MHC
molecules
Work with
Cytotoxic T cells Class 2 MHC
molecules
Work with both
Cytotoxic T CellsHelper T cells
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Immune Response
Primary Immune
Response
Takes 10 - 17 days
from initial exposure toan antigen
Produces B and T
cells
Secondary Immune
Response
takes 2 - 7 days from
re-exposure to antigen
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Immune Responses
Humoral Immunity
involves B cells
produces antibodies
that circulate in theblood, plasma and
lymph
cells do not have to be
next to antigen to
attack
Cell-mediated
Immunity
involves T cells
cells must be next toantigens to attack
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Response to Nearly All Antigens
Helper T cells
attach to macrophage that has attacked an
antigen
often uses CD4 receptors
releases interleukin (Cytokine)
activates Cytotoxic T cells and Plasma B cells
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Cell-mediated Response Cytotoxic T cells
attach to infected cells / Cancer Cells
Usually uses a CD8 receptor
perforin (protein) makes a pore in membrane
ions and water enters pores
infected cell lyses
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B Cells: A Response to
Extracellular Pathogens Response to
extracellular
pathogens
Plasma B cells
produce antibodies
Memory B cells
live a long time
and can help
produce other Bcells quickly when
re-infected by the
same antigen
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Antibodies
A group of globular
serum proteins called
immunoglobulins
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Immunity in Health and Disease
Active Immunity
Getting the disease
Immunizations
(Vaccinations) Passive Immunity
Antibodies transferred
from one individual to
another pregnancy and breast
feeding
injection of antibodies
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Stages
of HIV
Infect-
ions