Download Infectious Disease and the Immune System Ch. 39

Infectious Disease and
the Immune System
Ch. 39
What are Infectious Diseases?
• Pathogen- bacteria, virus,
fungi, protozoa, etc…
– Any organism that disrupts
homeostasis
• Infectious Disease- change in
homeostasis by a pathogen
– Foreign pathogen
– Symbiotic pathogen that has
changed location
– Body is too weak for symbiotic
relationship
Types of Diseases?
• Infections diseases Pathogens
• Genetic disease gene
mutations
– Trisomy 21 (Down’s Syndrome)
• Environmental toxin exposure
– Cirrhosis
• Malnutrition limited food
supply
– Scurvy
• Cancer Carcinogens
– Lung Cancer
– Brain tumor
• Diabetes Genetics/Malnutrition
Identifying a New Disease
• Robert Koch; 1876
– Isolated anthrax from dead
animals and injected into healthy
ones
– Healthy animals died of disease
– Isolate pathogen in new dead
animals and found it to be the
same anthrax
• Koch’s Postulates:
1) Same pathogen must be found
in the host in every case
2) Pathogen must be grown on a
culture plate
3) Once grown, the pathogen
must give a healthy organism
the disease
4) Pathogen in the new host and
the old host must be the same
Spreading Disease
• 4 methods:
1) Direct Contact
-colds, STDs, Flu
Carriers- transmit disease but are
not effected by it
Incubation period- time it takes
after infection for symptoms
to appear
2) By Object
-food poisoning
3) Airborne transmission
-Strep throat
4) Vectors
-insects, birds, farm animals
-Malaria; mosquitoes
-Black Plague; fleas on rats
Disease Patterns
• Endemic Disease:
always present in the
population; cases
fluctuate with seasons
ex. Cold, flus, food
poisoning
• Epidemic Disease:
small population see
dramatic increase in a
new or uncommon
disease
ex. SARS
• Pandemic Disease:
global spread of disease
ex. HIV/AIDS; H1N1
Pathogen Attack!
• Pathogens damage host cells
through toxins
proteins/compounds that:
-inhibit cellular functions
-destroy the plasma
membrane
-produce fever
-inhibit cell signaling
Botulin neurotoxin
-most powerful
discovered so far; 75 ng
can kill a human
-prevents
neurotransmitter
release
-causes muscle paralysis
-used to make BOTOX
The Immune System
• Immune system- various
methods of defending,
isolating, and removing
pathogens from the body
• Innate Immunity
– Nonspecific defenses against
all pathogens
• Acquired Immunity
– Defense against specific
pathogens that is built over
time
– Made from Antibody
immunity and Cellular
immunity
Innate Immunity
• Levels of defense:
1) Skin- protective barrier
covering the body
2) Secretions- mucus, oil,
sweat, tears, and any other
fluid used to wash away
pathogens
– Also contain lysozyme enzyme
3) Inflammation- increase
blood flow and temperature of
infected area to kill pathogens
– Caused by Histamine, AA
hormone released by
Basophils and Eosinophils
(white blood cells)
Innate Immunity
4) Phagocytes- white blood cells
that kill pathogens with
phagocytosis
– Endocytosis of bacteria
Types of Phagocytes:
1) Macrophages- white blood cell
in tissue
2) Neutrophil- second wave if
macrophages are not enough
3) Monocytes- travel in the blood
to infection site and become
macrophages
Over time infections produce pus
(collection of living and dead
macrophages)
Innate Immunity
5) Interferons- protective
proteins that cover cells so
viruses cannot attach to
host cells
– Specific for different
types of host cells
– Also produce antiviral
proteins to stop virus
reproduction
Macrophages from the
innate immune system are
used to build the acquired
immune system
Acquired Immunity
• ID system through antigens
and antibodies
• Antigens- proteins in the cell
membrane used in cellular
communication
– A-type Blood A-type
antigens
– Bacterial membrane
antigens signal attachment
mechanism
• Antibodies- proteins in the
blood produced to attach to
specific antigens
– If the antibody finds the
antigen is was made for; that
organism attached to those
antigens is destroyed
Lymphatic System
• System for monitoring tissue fluid and
filter body fluids for infection
• Lymph- tissue fluid inside lymph vessels
– Travels through capillaries and veins on
the Lymph system
– Return tissue fluid to blood in the
shoulders
• Lymph nodes- mass of tissue for filtering
lymph with lymphocytes (white blood
cells)
• Tonsils- filter out pathogens we breath in
• Spleen/Thymus Gland- store lymphocytes
• Lymphocytes react with pathogens to
build antibodies
– Create Antibody and Cellular Immunity
Antibody Immunity
1) Infection occurs and
macrophages eat
pathogens
2) Antigens from pathogens
are placed on the
macrophage membrane
3) Lymphocytes (Helper-T
cells and B cells) bind to
antigens and create
plasma cells
4) Plasma cells produce 2000
antibodies/sec to kill
infection
5) Memory-B cells and
antibodies stay in blood to
stop infection quickly if it
returns
Cellular Immunity
1) Infection occurs and
macrophage eats pathogens
2) Antigens from pathogens are
placed on the macrophage
membrane
3) Cytotoxic (Killer) T cells
activate and release perforin
on to pathogens
4) Perforin eats through
membranes, killing the
pathogens
Over active reaction can lead to
autoimmune disorders
-body tissue is attacked
-transplanted organs are
attacked
Passive vs. Active Immunity
Passive:
NaturalAntibodies pasted down from
mother/breast milk
ArtificialTake antibodies from organism
already immune from disease
Active:
VaccineInject person with weak or dead
pathogen; body easily kills it and
makes antibodies
Cowpox is a vaccine for Smallpox
Homework: HIV/AIDS paper
• Write a 1 page essay on HIV:
– How it spreads?
– How does it effect the immune
system?
– What is AIDS?
– What are methods of
controlling the spread of HIV?
– Are there ways to cure HIV?
A lot of content so be
brief in your explanations