Transcript The Immune System

The Immune System
Chapter 40
Agents of Disease
• The human body provides a suitable
environment for many microorganisms: it is
moist, warm and full of nutrients.
▫ Not all microorganisms are harmful; some are
beneficial.
 Bacteria living in the intestines aid in digestion.
▫ Microorganisms that cause disease are called
pathogens.
 Agents of disease include viruses, bacteria, protists,
worms, fungi, arachnids and insects.
Infectiously Cute Plush Microbes!
Section 40-1
Pathogen
Types
Viruses
Bacteria
Protists
Worms
Fungi
Pathogens and Disease
Chickenpox
Agent That Causes
Disease
Rhinovirus
Two types (A, B),
plus subtypes
Varicella
Measles
Paramyxovirus
Tuberculosis
Mycobacterium
tuberculosis
Neisseria meningitidis
Vibrio cholerae
Clostridium tetani
Trypanosoma
Disease
Common cold
Influenza
Meningitis
Cholera
Tetanus
African sleeping
sickness
Malaria
Amoebic dysentery
Schistosomiasis
Beef tapeworm
Athlete’s foot
Ringworm
Plasmodium
Entamoeba histolytica
Schistosoma
Taenia saginata
Imperfect fungi
Imperfect fungi
Method of
Transmission
Airborne; direct contact with infected person
Airborne; droplet infection; direct contact with
infected person
Airborne; direct contact with infected person
Droplets in air; direct contact with secretions of
infected person
Droplets in air; contaminated milk and dairy
products
Direct contact with a carrier
Contaminated drinking water
Contaminated wound; usually puncture wound
Spread by tsetse fly
Spread by Anopheles mosquitoes
Contaminated drinking water
Freshwater streams and rice paddies
Contaminated meat
Contact with infected person
Exchange of hats, combs, or athletic head gear with
infected person
Infectious Disease
• Diseases caused by pathogens that can be
transmitted from one individual to another are
called infectious diseases.
• Methods of transmittal include:
▫ Sneezing
Infectious Disease
• Diseases caused by pathogens that can be
transmitted from one individual to another are
called infectious diseases.
• Methods of transmittal include:
▫ Sneezing
▫ Coughing
Infectious Disease
• Diseases caused by pathogens that can be
transmitted from one individual to another are
called infectious diseases.
• Methods of transmittal include:
▫ coughing
▫ Sneezing
▫ Contaminated food or water
Urban migration and dense populations offer the perfect
environment for the spread of microbial pathogens.
Infectious Disease
• Diseases caused by pathogens that can be
transmitted from one individual to another are
called infectious diseases.
• Methods of transmittal include:
▫
▫
▫
▫
coughing
Sneezing
Contaminated food or water
Physical contact
Infectious Disease
• Diseases caused by pathogens that can be
transmitted from one individual to another are
called infectious diseases.
• Methods of transmittal include:
▫
▫
▫
▫
▫
coughing
Sneezing
Contaminated food or water
Physical contact
Infected animals
Fighting Disease….
Antibiotics
Sir Alexander
Fleming
discovered the
first antibiotic,
penicillin, by
mistake.
Antibiotics
•Antibiotics work by
destroying the cell wall
of bacteria.
•They are specific to
certain bacteria.
•They are ineffective
against viruses.
•Overuse of antibiotics
has led to resistant
strains of bacteria.
Methicillin-resistant Staphylococcus aureus
Vaccines
• A vaccine is a weakened or dead form of a
pathogen or its toxin.
• Vaccines stimulate the immune system to
protect the body against future invasions by the
pathogen.
• The first vaccine was developed by Edward
Jenner against the Small Pox virus.
The first vaccination: Edward Jenner used pus from the
hand of a dairy maid in 1796
Image: © Bettmann/Corbis
The Immune System
• First Line of Defense
▫ Physical and chemical barriers
 Skin
 Secretions
 Stomach acid
The Immune System
• Second Line of Defense
▫ Inflammatory response – phagocytes
 Redness, swelling, heat, fever
▫ Interferon
Video 1
The Immune System
• Third Line of Defense
▫ The immune response - lymphocytes
 Antigens (foreign substances) that get past the first
and second lines of defense will trigger the
production of antibodies by white blood cells.
 These antibodies are specific for the antigen that
caused their formation.
 Antibodies bind to antigens disabling them.
Section 40-2
Structure of an Antibody
Antigenbinding
sites
Antigen
Antibody
Immunity
• Once activated, the immune system white blood
cells “remember” the antigens.
• Future invasions by the antigen are destroyed
immediately by circulating antibodies.
Antibody Concentration
Section 40-2
Immune Response
Interval
between
exposures
First
exposure
Second
exposure
Time
Passive Immunity
• “Borrowed” immunity - the immune system is
not activated.
• Temporary.
▫ Antibodies from another source are taken to
combat the disease (antibiotics).
▫ Eventually the antibodies are recognized as
foreign and destroyed.
Active Immunity
• The immune system is activated and produces
antibodies.
• Lasts a lifetime.
• Vaccines stimulate active immunity.
Rejection
• Our tissues contain their own antigens (proteins
capable of generating antibodies).
• Our immune system recognizes these antigens as
belonging to ourselves, and does not produce
antibodies against them.
• When a tissue or organ is transplanted, the
recipient’s immune system will not recognize it as
“self” and will manufactures antibodies to destroy it.
• This is known as rejection.
• Drugs are administered to suppress the immune
system and lessen this effect.
Immune System Disorders
Immune System Disorders
• Allergies (a.k.a. immune system gone haywire)
▫ The immune system decides certain antigens are
deadly …(cat fur, dust, mold, pollen, bee stings,
poison ivy) and an inflammatory response is
triggered against these allergens.
▫ Histamines released by certain cells cause the
classic symptoms: watery itchy eyes, runny nose,
sneezing, wheezing, coughing, rash….. fun, fun,
fun…..
Poison Ivy
Immune System Disorders
• Asthma
▫ An allergic reaction causing the air passageways to
narrow therefore restricting breathing.
▫ Can be triggered by respiratory infections,
exercise, emotional stress, cold air, dust, pollen,
dander, and some medications.
▫ The tendency towards asthma is inherited.
Immune System Disorders
• Autoimmune diseases
▫ The immune system fails to recognize itself and
mistakenly identifies parts of the body as foreign
and attacks.
 Type 1 diabetes
 Rheumatoid arthritis
 Multiple sclerosis
Multiple Sclerosis
Immune System Disorders
• AIDS Acquired Immune Deficiency Syndrome
▫ A virus, HIV, destroys key white blood cells
involved in the immune response.
▫ A person with AIDS does not have a functional
immune system.
▫ Previous immunity to diseases no longer is
effective.