Download A little history…

Unit 12:
Fighting Disease
(Ch. 17)
A little history…
• Before 1900s, surgery was very
risky. About 45% of all people
who had surgery died. People
didn’t know that microorganisms
existed.
• Joseph Lister- 1860s- surgeon
who washed his hands before
surgery and covered wounds with
bandages. Reduced surgery
deaths to about 15%.
A little history…
• Louis Pasteur- 1860s- boiled beef
broth to kill microorganisms.
• Robert Koch- proved that each
sickness is caused by a different
microorganism.
Infectious Disease
• Pathogen- organism that causes
disease
• Infectious disease- caused by a living
thing in the body (pathogen gets
inside body).
• Pathogens damage individual cells.
• 4 classes of pathogens: bacteria,
viruses, fungi, protists.
Bacteria
• Single-celled organisms
• Cause ear infections, strep throat, food
poisoning, etc.
• Some bacteria damage cells directly,
others release toxins.
• Toxin- a poison that damages cells.
• Tetanus (lockjaw) - bacteria get into wound
and release toxin that damages nervous
system.
Viruses
• Much smaller than bacteria.
• Viruses aren’t alive! They cannot
reproduce unless they are in a living
cell.
• Ex: cold and flu.
• Not treated with antibiotics.
Fungi
• Grow best in dark, warm places.
• Ex: Athlete’s Foot and Ringworm
Protists
• Malaria- blood infection, common in
tropical areas, spread by
mosquitoes.
• Amebic Dysentery- spread through
contaminated water.
• African Sleeping Sickness- spread by
tsetse flies. Brain infection that
causes severe fatigue.
How Disease Spreads
• Contact with infected people- hugging,
kissing, shaking hands, drinking,
sneezing, coughing.
• Soil, Food, Water- live in soil and
spread through unclean food or
water.
• Contaminated Objects- microorganisms
live on surfaces (cold and flu spread
this way).
• Infected Animals- Animals/insects bite
people and spread disease (Lyme
Disease from ticks, Malaria from
mosquitoes).
The Body’s Defenses
• Lines of defense: skin, breathing
passages, mouth and stomach. Trap
most of the pathogens we come in
contact with.
• Skin- Oil and sweat kill pathogens.
They also fall off with dead skin
cells.
• Pathogens can enter skin when it is
damaged or cut.
• Breathing Passages- cilia, mucus, and
sneezing get rid of pathogens.
• Mouth and Stomach- saliva and
stomach acid kill pathogens.
The Inflammatory Response
• Inflammatory Response- the body’s
second line of defense.
• Fluid and WBCs leak from vessels into
nearby tissues. WBCs fight
pathogens.
• Called the body’s general defense
because it is the same regardless of
the pathogen.
• WBCs- There are 4 types.
• Phagocyte- type of WBC that is involved in
the inflammatory response. Engulf
pathogens.
• Inflammation- Blood vessels widen and blood
flow increases to bring WBCs to injury.
Swelling can occur.
• Fever- helps you fight disease by killing
pathogens.
The Immune System
• Infection that causes fever triggers
body’s 3rd line of defense- the
immune response.
• The immune system can distinguish
between different kinds of pathogens.
• Immune system cells react to each kind
of pathogen with a defense targeted
specifically at that pathogen.
• Lymphocyte- WBC that distinguishes
between different kinds of pathogens.
• 2 types: T cells and B
cells.
T Cells
• T cells- Identify pathogens and
distinguish one from the other.
• You have tens of millions of T cells.
• Each kind of T cell recognizes a different
type of pathogen.
• Antigens- markers on cell surface that
identify cell
B Cells
• B cells- produce proteins that destroy
pathogens (antibodies).
• Each B cell produces one kind of
antibody.
• Each antibody has a different structure.
• Antigens and antibodies fit together like
puzzle pieces - their pairing is specific.
- The Body’s Defenses
The Immune System
• The immune
system includes T
cells and B cells.
The cells work
together to fight
infections.
AIDS
• AIDS- Acquired Immunodeficiency
Syndrome
• HIV- Human Immunodeficiency Virusvirus that causes AIDS
• HIV is the only known virus to directly
attack and destroy T cells.
• People can have HIV for several years
before they know they have it.
AIDS
• More than 40 million people in the world
are infected with HIV.
• HIV destroys T cells, body’s defenses
are weakened.
• HIV then becomes AIDS.
• Most people with HIV/AIDS die of
common colds or other sicknesses.
• There is no cure for AIDS.
AIDS
• HIV must be inside a living cell to
reproduce.
• HIV spreads through bodily fluid contact
• Common causes on infection include sexual
contact, needles, blood transfusions
(before 1985).
• NOT spread by touching someone.
Preventing Disease
• Immunity- body’s ability to destroy
pathogens before they can cause disease.
• 2 types of immunity- active and passive.
Active Immunity
• Body produces antibodies to fight pathogens.
• A person acquires active immunity when their
own immune system produces antibodies in
response to the presence of a pathogen.
Active Immunity
• Immune Response- some T and B cells keep
a “memory” of the pathogen.
• If that pathogen enters the body again,
memory cells recognize antigen.
• Memory cells quickly start immune response
so you don’t get sick.
• Active immunity protects you for several
years or a whole lifetime.
Active Immunity
• Vaccination- Antigens of virus are purposely
introduced into the body.
• Vaccine- substance used in a vaccination.
• Consists of weakened or killed virus.
• You usually don’t get sick, but you get a
memory of the virus.
- Preventing Infectious Disease
Active Immunity
• A person acquires active immunity when his or her
own immune system produces antibodies in
response to the presence of a pathogen.
When You Get Sick
• Antibiotics- chemical that kills
bacteria or slows their growth
• Antibiotics do not work on viruses!
• For a speedy recovery, eat well, drink
plenty of fluids, and get lots of
sleep.
Passive Immunity
• Results when antibodies (instead of
antigens) are given to a person.
• Lasts only a few months.
• Babies get passive immunity from mom.
Comparing and Contrasting
Active Immunity
The body
makes
antibodies.
Memory cells
recognize antigens.
Immunity may last
for years or a
lifetime.
Passive
Immunity
Can prevent
diseases
May involve
an injection
Antibodies are given;
the body does not
make antibodies.
Immunity can be
acquired from the
mother during
pregnancy.
Immunity lasts
only a few
months.
Noninfectious Disease
• Diseases that aren’t caused by
pathogens.
• Have become more common than
infectious diseases.
• Can’t be passed from person to person.
• Cardiovascular Disease- leading cause
of death in America.
Noninfectious Disease- Allergies
• Allergies- immune system is overly
sensitive to a foreign substance that
isn’t harmful to the body.
• Allergen- substance that causes
allergy (pollen, dust, mold, foods,
medicines, pets).
• Histamine- chemical that causes
allergy symptoms.
• To reduce allergies, avoid allergens!
Noninfectious Disease
• Asthma- a condition in which the
respiratory passages narrow significantly.
Causes shortness of breath.
Noninfectious Disease- Diabetes
• Diabetes- a condition where the
pancreas does not produce insulin, or
the body’s cells do not use it
properly.
• Insulin- allows body cells to take in
glucose and use it for energy.
• A person with diabetes has high levels
of blood glucose, but their body
cells do not have enough glucose.
Noninfectious Disease- Diabetes
• Diabetes symptoms: weight loss,
weakness, extreme hunger, excessive
thirst, frequent urination, blindness,
kidney failure, heart disease.
• Type 1 Diabetes- begins in childhood,
pancreas produces little insulin.
• Type 2 Diabetes- develops during
adulthood, can control symptoms by
diet, weight control, and exercise.
Noninfectious Disease- Cancer
• Cancer- disease where body cells
divide uncontrollably and destroy
healthy tissue in the process.
• Unchecked cells form tumors (mitosis)
which feed off blood supply to body
parts, and can spread throughout body.
• Not all tumors are cancerous.
Noninfectious Disease- Cancer
• Causes of cancer- genetics,
carcinogens, diet, lifestyle.
• Carcinogens- environmental factors
that cause cancer.
• Treatment- surgery, drugs, radiation
(high energy waves that kill cancer).
• To prevent cancer, avoid carcinogens.