CHAPTER 43 
THE BODY’S 
DEFENSES
The Nature of Disease 
• Pathogenic Organisms 
• Genetic Disorders 
• Toxic Chemicals 
• Other Environmental Factors 
• Physical Damage to Organs 
• Nutritional Disorders
Types of Pathogenic 
Organisms 
• Viruses 
• Bacteria 
• Protozoan 
• Fungi 
• Animal 
• Parasites
Mechanisms of 
Disease by Pathogens 
• Utilization of host nutritional 
resources 
• Physical damage to host tissues 
• Production of toxic substances 
• Chromosomal and gene damage 
• Body cells behave abnormally
Viruses 
capsid 
envelope 
nucleic acid
Bacteria 
cell wall 
plasma 
membrane 
cytoplasm 
circular DNA
Defense Mechanisms 
1. External defense 
2. Internal Defense 
3. Immune Defense
1st Line of Defense 
• Skin acts as barrier to microbes and viruses 
- sweat has a low pH 
• Mucus traps foreign particles 
• Tears 
- Lysozyme has antimicrobial action 
• Gastric stomach acid
Body Coverings: The Skin 
sebaceous 
glands 
sweat gland 
epidermis
Body Coverings: 
Mucous Membranes 
mucus 
cilia 
columnar 
epithelium
2nd Line of Defense 
• Phagocytic cells (WBCs) 
- N L M E B 
- Natural Killer (NK) Cells: attack virus 
infected cells 
• Inflammatory Response 
• Antimicrobial proteins 
- Lysozyme 
- Interferon 
- Antibodies
Nonspecific Phagocytosis 
Neutrophils 
Monocytes 
Eosinophils
Mechanism of Phagocytosis 
Mechanism of Phagocytosis 
Macrophage
Lymphatic System
Inflammatory Response 
Histamine & 
prostaglandins 
released 
Capillaries dilate 
Clotting begins 
Chemotactic 
factors attract 
phagocytic cells 
Phagocytes 
consume 
pathogens & 
cell debris
Characteristics of Immunity 
• Recognition of self versus non-self 
• Response is specific 
• Retains a “memory” allowing an 
accelerated second response 
• Can respond to many different 
materials 
• Involves lymphocytes and 
antibodies
Types of Immunity 
• Active Immunity 
- Naturally-Acquired Active Immunity 
- Artificially-Acquired Active Immunity 
• Passive Immunity 
- Naturally-Acquired Passive Immunity 
- Artificially-Acquired Passive Immunity
Types of 
Acquired 
Immunity
Active Immunity 
• The production of antibodies against a 
specific disease by the immune system. 
• Naturally acquired through disease 
• Artificially acquired through vaccination 
– Vaccines include inactivated toxins, killed 
microbes, parts of microbes, and viable but 
weakened microbes. 
• Active immunity is usually permanent
• A vaccinated person has a secondary 
response based on memory cells when 
encountering the specific pathogen. 
– Routine immunization against infectious 
diseases such as measles and whooping 
cough, and has led to the eradication of 
smallpox, a viral disease. 
– Unfortunately, not all infectious agents are 
easily managed by vaccination. 
• HIV vaccine in the works
Passive Immunity 
• Passive Immunity- Protection 
against disease through antibodies 
produced by another human being 
or animal. 
• Effective, but temporary 
• Ex. Maternal antibodies 
• Colostrum.
• Passive immunity can be transferred 
artificially by injecting antibodies from an 
animal that is already immune to a disease 
into another animal. 
– Rabies treatment: injection with antibodies 
against rabies virus that are both passive 
immunizations (the immediate fight) and active 
immunizations (longer term defense).
Immune System Response to 
Antigens 
Humoral Immunity 
• Involves antibodies (secreted from B 
cells) dissolved in the blood plasma. 
• Demonstrated as a immune response 
using only the blood serum. 
• Defense against bacteria, bacterial 
toxins, & viruses.
Immune System Response to 
Antigens 
Cell-Mediated Immunity 
• Involves the activities of specific 
white blood cells (T cells). 
• Defense against cancer cells, virus-infected 
cells, fungi, animal parasites, 
& foreign cells from transplants.
Lymphocyte Formation
B Cells 
• Mature in bone marrow 
• Involved in humoral immunity 
• Once activated by antigen, 
proliferate into two clones of cells: 
plasma cells that secrete 
antibodies and memory cells that 
may be converted into plasma cells 
at a later time
B Cells 
antibodies
B Cells 
B Cells
Activation of B Cells by 
Antigen 
antigen
Clonal Selection
Clonal Selection 
plasma cells memory cells 
antibodies
Humoral Immune Response 
time (days) 
antibody concentration 
first 
exposure to 
antigen A
Humoral Immune Response 
time (days) 
antibody concentration 
first exposure 
to antigen A 
primary response: 
concentration of 
anti-A antibody second exposure 
to antigen A
Humoral Immune Response 
time (days) 
antibody concentration 
secondary response: 
concentration of anti-A 
antibody 
second exposure 
to antigen A 
first exposure 
to antigen B
Humoral Immune Response 
time (days) 
antibody concentration 
primary 
response: 
concentration of 
anti-B antibody 
first 
exposure to 
antigen B
• Antibodies constitute a group of globular 
serum proteins called immunoglobins 
(Igs). 
– A typical antibody molecule has two identical 
antigen-binding sites specific for the epitope 
that provokes its production.
Antibody Molecule 
antigen binding sites 
antigen 
light chains heavy chains
Mechanisms on Antibody 
Action 
• Precipitation of soluble antigens 
• Agglutination of foreign cells 
• Neutralization 
• Enhanced phagocytosis 
• Complement activation leading to cell lysis 
• Stimulates inflammation
• The binding of antibodies to antigens to form 
antigen-antibody complexes is the basis of 
several antigen disposal mechanisms.
The classical complimentary pathway, 
resulting in lysis of a target cell
Immunoglobin Classes 
IgM 
• 1st response to antigen 
• Effective in agglutination 
• Can’t cross placenta 
IgG 
• Most common form 
• Crosses blood vessels 
• Crosses placenta 
(passive immunity to 
fetus) 
IgA 
• Secreted from mucus 
membranes 
• Prevents attachment of 
bacteria to epithelial surface 
• In colostrum 
IgD 
• B cell activation 
• Can’t cross placenta 
IgE 
• Histamine 
reactions and 
allergies
Overview of Immune System Responses
T Cells 
• Mature in thymus 
• Involved in cell-mediated immunity 
• Activated when another cell 
presents antigen to them 
• Several types of T cells: cytoxic T 
cells, helper T cells, suppressor T 
cells, and memory T cells
T Cells 
• There are two main types of T cells, and 
each responds to one class of MHC 
molecule. 
– Cytotoxic T cells (TC) have antigen receptors 
that bind to protein fragments displayed by the 
body’s class I MHC molecules. 
– Helper T cells (TH) have receptors that bind to 
peptides displayed by the body’s class II MHC 
molecules.
Cytotoxic T Cell 
perforin 
pores in target cell
Helper T Cells 
T cell receptor 
helper 
T cell 
bacterium 
bacterial 
antigens 
macrophage interleukin 1
The central role of helper T cells
• The central role in Helper T cells in an 
infected cell
–T-independent antigens 
• T cells activated by binding to certain 
antigens 
• No memory cells generated 
•Weaker response than t-dependent 
–T-dependent antigens 
• Most antigens require co-stimulation to 
evoke a B-cell response 
• Antibody production stimulated with help 
from TH 
• Most antigens are t-dependent
• T-dependent 
antigens- can trigger a 
humoral immune 
response by B cells 
only with the 
participation of helper T 
cells.
Tissue/Organ Transplants 
• Major Histocomatibility Complex 
(MHC) 
- Bone marrow 
- Organs
Abnormal immune function can 
lead to disease 
• Malfunctions of the immune system can 
produce effects ranging from the minor 
inconvenience of some allergies to the 
serious and often fatal consequences of 
certain autoimmune and immunodeficiency 
diseases.
Abnormal Immune 
Function 
• Autoimmune Disease 
• Allergy 
• Immunodeficiency
Autoimmune Disease 
• Rheumatoid arthritis 
• Type I Diabetes 
• MS 
• Lupis 
• Crohn’s disease 
• Grave’s disease
ABO Blood Types 
Phenotype Genotype 
O i i 
A I A I A or I A i 
B I B I B or I B i 
AB I A I B
ABO Blood Types 
Type 
A 
Produces 
anti-B 
antibodies 
b 
b 
b 
b 
b 
b 
b 
b
ABO Blood Types 
Type 
B 
Produces 
anti-A 
antibodies 
a 
a 
a 
a 
a 
a a 
a 
a 
a
ABO Blood Types 
Type 
AB 
Produces 
neither 
anti-A nor 
anti-B 
antibodies
ABO Blood Types 
Type 
O 
Produces 
both anti-A 
and anti-B 
antibodies 
a 
a 
a 
a 
a 
a 
a 
a 
a 
a 
b 
b 
b 
b 
b 
b 
b 
b
Rh Factor 
and 
Pregnancy 
RH+ indicates protein 
RH- indicates no protein 
15% of population is RH-
Rh Factor 
and 
Pregnancy 
Rh+ mother w/Rh- baby– no problem 
Rh- mother w/Rh+ baby– problem 
Rh- mother w/Rh- father– no problem 
Rh- mother w/Rh- baby-- no problem 
RhoGAM used @ 28 weeks
Allergy (Immune Hypersensitivity) 
• Hypersensitive response to certain 
environmental allergens 
• Food, pollen, pet dander, asthma, bee 
sting 
• Anaphylactic shock 
- epinephrine
• Mast cells, IgE, 
and the allergic 
response.
AIDS 
Problems 
Acquired Immunodeficiency 
Syndrome 
HIV (virus) attacks T-cells 
Weakens or eliminates immune 
system 
Susceptible to many fatal diseases
• Transmission of HIV requires the transfer of 
body fluids containing infected cells, such as 
semen or blood, from person to person. 
– Unprotected sex 
– Nonsterile needles 
– HIV transmission among heterosexuals is 
rapidly increasing as a result of unprotected sex 
with infected partners. 
– HIV in Africa and Asia- primarily by heterosexual 
sex
AIDS 
• In 1983, a retrovirus, now called human 
immunodeficiency virus (HIV), had been 
identified as the causative agent of AIDS.
• With the AIDS mortality close to 100%, HIV 
is the most lethal pathogen ever 
encountered. 
– Molecular studies reveal that the virus probably 
evolved from another HIV-like virus in 
chimpanzees in central Africa and appeared in 
humans sometimes between 1915 and 1940. 
• These first rare cases of infection and AIDS went 
unrecognized.
AIDS
AIDS
• HIV Testing: 
– The HIV antibody test has be used to screen 
all blood supplies in the U.S. since 1985. 
• May take weeks or months before anti-HIV 
antibodies become detectable. 
- Drug treatment available 
- Best prevention is education and protected sex

Ch 43 immunity

  • 1.
    CHAPTER 43 THEBODY’S DEFENSES
  • 2.
    The Nature ofDisease • Pathogenic Organisms • Genetic Disorders • Toxic Chemicals • Other Environmental Factors • Physical Damage to Organs • Nutritional Disorders
  • 3.
    Types of Pathogenic Organisms • Viruses • Bacteria • Protozoan • Fungi • Animal • Parasites
  • 4.
    Mechanisms of Diseaseby Pathogens • Utilization of host nutritional resources • Physical damage to host tissues • Production of toxic substances • Chromosomal and gene damage • Body cells behave abnormally
  • 5.
  • 6.
    Bacteria cell wall plasma membrane cytoplasm circular DNA
  • 7.
    Defense Mechanisms 1.External defense 2. Internal Defense 3. Immune Defense
  • 8.
    1st Line ofDefense • Skin acts as barrier to microbes and viruses - sweat has a low pH • Mucus traps foreign particles • Tears - Lysozyme has antimicrobial action • Gastric stomach acid
  • 9.
    Body Coverings: TheSkin sebaceous glands sweat gland epidermis
  • 10.
    Body Coverings: MucousMembranes mucus cilia columnar epithelium
  • 11.
    2nd Line ofDefense • Phagocytic cells (WBCs) - N L M E B - Natural Killer (NK) Cells: attack virus infected cells • Inflammatory Response • Antimicrobial proteins - Lysozyme - Interferon - Antibodies
  • 12.
  • 13.
    Mechanism of Phagocytosis Mechanism of Phagocytosis Macrophage
  • 14.
  • 15.
    Inflammatory Response Histamine& prostaglandins released Capillaries dilate Clotting begins Chemotactic factors attract phagocytic cells Phagocytes consume pathogens & cell debris
  • 16.
    Characteristics of Immunity • Recognition of self versus non-self • Response is specific • Retains a “memory” allowing an accelerated second response • Can respond to many different materials • Involves lymphocytes and antibodies
  • 17.
    Types of Immunity • Active Immunity - Naturally-Acquired Active Immunity - Artificially-Acquired Active Immunity • Passive Immunity - Naturally-Acquired Passive Immunity - Artificially-Acquired Passive Immunity
  • 18.
  • 19.
    Active Immunity •The production of antibodies against a specific disease by the immune system. • Naturally acquired through disease • Artificially acquired through vaccination – Vaccines include inactivated toxins, killed microbes, parts of microbes, and viable but weakened microbes. • Active immunity is usually permanent
  • 20.
    • A vaccinatedperson has a secondary response based on memory cells when encountering the specific pathogen. – Routine immunization against infectious diseases such as measles and whooping cough, and has led to the eradication of smallpox, a viral disease. – Unfortunately, not all infectious agents are easily managed by vaccination. • HIV vaccine in the works
  • 21.
    Passive Immunity •Passive Immunity- Protection against disease through antibodies produced by another human being or animal. • Effective, but temporary • Ex. Maternal antibodies • Colostrum.
  • 22.
    • Passive immunitycan be transferred artificially by injecting antibodies from an animal that is already immune to a disease into another animal. – Rabies treatment: injection with antibodies against rabies virus that are both passive immunizations (the immediate fight) and active immunizations (longer term defense).
  • 23.
    Immune System Responseto Antigens Humoral Immunity • Involves antibodies (secreted from B cells) dissolved in the blood plasma. • Demonstrated as a immune response using only the blood serum. • Defense against bacteria, bacterial toxins, & viruses.
  • 24.
    Immune System Responseto Antigens Cell-Mediated Immunity • Involves the activities of specific white blood cells (T cells). • Defense against cancer cells, virus-infected cells, fungi, animal parasites, & foreign cells from transplants.
  • 25.
  • 26.
    B Cells •Mature in bone marrow • Involved in humoral immunity • Once activated by antigen, proliferate into two clones of cells: plasma cells that secrete antibodies and memory cells that may be converted into plasma cells at a later time
  • 27.
  • 28.
    B Cells BCells
  • 29.
    Activation of BCells by Antigen antigen
  • 30.
  • 31.
    Clonal Selection plasmacells memory cells antibodies
  • 32.
    Humoral Immune Response time (days) antibody concentration first exposure to antigen A
  • 33.
    Humoral Immune Response time (days) antibody concentration first exposure to antigen A primary response: concentration of anti-A antibody second exposure to antigen A
  • 34.
    Humoral Immune Response time (days) antibody concentration secondary response: concentration of anti-A antibody second exposure to antigen A first exposure to antigen B
  • 35.
    Humoral Immune Response time (days) antibody concentration primary response: concentration of anti-B antibody first exposure to antigen B
  • 36.
    • Antibodies constitutea group of globular serum proteins called immunoglobins (Igs). – A typical antibody molecule has two identical antigen-binding sites specific for the epitope that provokes its production.
  • 37.
    Antibody Molecule antigenbinding sites antigen light chains heavy chains
  • 38.
    Mechanisms on Antibody Action • Precipitation of soluble antigens • Agglutination of foreign cells • Neutralization • Enhanced phagocytosis • Complement activation leading to cell lysis • Stimulates inflammation
  • 39.
    • The bindingof antibodies to antigens to form antigen-antibody complexes is the basis of several antigen disposal mechanisms.
  • 40.
    The classical complimentarypathway, resulting in lysis of a target cell
  • 41.
    Immunoglobin Classes IgM • 1st response to antigen • Effective in agglutination • Can’t cross placenta IgG • Most common form • Crosses blood vessels • Crosses placenta (passive immunity to fetus) IgA • Secreted from mucus membranes • Prevents attachment of bacteria to epithelial surface • In colostrum IgD • B cell activation • Can’t cross placenta IgE • Histamine reactions and allergies
  • 42.
    Overview of ImmuneSystem Responses
  • 43.
    T Cells •Mature in thymus • Involved in cell-mediated immunity • Activated when another cell presents antigen to them • Several types of T cells: cytoxic T cells, helper T cells, suppressor T cells, and memory T cells
  • 44.
    T Cells •There are two main types of T cells, and each responds to one class of MHC molecule. – Cytotoxic T cells (TC) have antigen receptors that bind to protein fragments displayed by the body’s class I MHC molecules. – Helper T cells (TH) have receptors that bind to peptides displayed by the body’s class II MHC molecules.
  • 45.
    Cytotoxic T Cell perforin pores in target cell
  • 46.
    Helper T Cells T cell receptor helper T cell bacterium bacterial antigens macrophage interleukin 1
  • 47.
    The central roleof helper T cells
  • 48.
    • The centralrole in Helper T cells in an infected cell
  • 50.
    –T-independent antigens •T cells activated by binding to certain antigens • No memory cells generated •Weaker response than t-dependent –T-dependent antigens • Most antigens require co-stimulation to evoke a B-cell response • Antibody production stimulated with help from TH • Most antigens are t-dependent
  • 51.
    • T-dependent antigens-can trigger a humoral immune response by B cells only with the participation of helper T cells.
  • 52.
    Tissue/Organ Transplants •Major Histocomatibility Complex (MHC) - Bone marrow - Organs
  • 53.
    Abnormal immune functioncan lead to disease • Malfunctions of the immune system can produce effects ranging from the minor inconvenience of some allergies to the serious and often fatal consequences of certain autoimmune and immunodeficiency diseases.
  • 54.
    Abnormal Immune Function • Autoimmune Disease • Allergy • Immunodeficiency
  • 55.
    Autoimmune Disease •Rheumatoid arthritis • Type I Diabetes • MS • Lupis • Crohn’s disease • Grave’s disease
  • 56.
    ABO Blood Types Phenotype Genotype O i i A I A I A or I A i B I B I B or I B i AB I A I B
  • 57.
    ABO Blood Types Type A Produces anti-B antibodies b b b b b b b b
  • 58.
    ABO Blood Types Type B Produces anti-A antibodies a a a a a a a a a a
  • 59.
    ABO Blood Types Type AB Produces neither anti-A nor anti-B antibodies
  • 60.
    ABO Blood Types Type O Produces both anti-A and anti-B antibodies a a a a a a a a a a b b b b b b b b
  • 61.
    Rh Factor and Pregnancy RH+ indicates protein RH- indicates no protein 15% of population is RH-
  • 62.
    Rh Factor and Pregnancy Rh+ mother w/Rh- baby– no problem Rh- mother w/Rh+ baby– problem Rh- mother w/Rh- father– no problem Rh- mother w/Rh- baby-- no problem RhoGAM used @ 28 weeks
  • 63.
    Allergy (Immune Hypersensitivity) • Hypersensitive response to certain environmental allergens • Food, pollen, pet dander, asthma, bee sting • Anaphylactic shock - epinephrine
  • 64.
    • Mast cells,IgE, and the allergic response.
  • 65.
    AIDS Problems AcquiredImmunodeficiency Syndrome HIV (virus) attacks T-cells Weakens or eliminates immune system Susceptible to many fatal diseases
  • 66.
    • Transmission ofHIV requires the transfer of body fluids containing infected cells, such as semen or blood, from person to person. – Unprotected sex – Nonsterile needles – HIV transmission among heterosexuals is rapidly increasing as a result of unprotected sex with infected partners. – HIV in Africa and Asia- primarily by heterosexual sex
  • 67.
    AIDS • In1983, a retrovirus, now called human immunodeficiency virus (HIV), had been identified as the causative agent of AIDS.
  • 68.
    • With theAIDS mortality close to 100%, HIV is the most lethal pathogen ever encountered. – Molecular studies reveal that the virus probably evolved from another HIV-like virus in chimpanzees in central Africa and appeared in humans sometimes between 1915 and 1940. • These first rare cases of infection and AIDS went unrecognized.
  • 69.
  • 70.
  • 71.
    • HIV Testing: – The HIV antibody test has be used to screen all blood supplies in the U.S. since 1985. • May take weeks or months before anti-HIV antibodies become detectable. - Drug treatment available - Best prevention is education and protected sex