Disease as a Failure of
Homeostasis
Causes of Disease
Inherited Diseases – GENETIC
Down’s Syndrome
Cystic Fibrosis
Sickle Cell Anemia
Exposure to Toxins – POISONS
Lead Poisoning
Radiation Poisoning
Poor NutritionScurvy (Lack of Vitamin C)
Goiter (Low Iodine)
Organ Malfunction –
Heart Attack
Stroke (Brain)
Diabetes (Pancreas)
HIGH RISK BEHAVIORSLung Cancer (Smoking)
Skin Cancer (Tanning)
AIDS (Drug Addiction/Sexual
Activity)
PATHOGENS – Organisms that
interfere with NORMAL functions of
the body; they disrupt homeostasis
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VIRUSES
Small, non-living
“particles” of
genetic material that
invade living cells
Chicken Pox
HIV
Measles
Influenza
Virus injecting its
DNA into a cell
Bacterium (Bacteria is plural)
Bacteria- Singlecelled organisms
 Strep Throat
 Syphilis
 Food Poisoning
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Bacilli bacteria being surrounded
by White Blood Cells
Fungus (Fungi is plural)
Fungi can be
unicellular (1 cell) or
multicellular (Many
cells)
 Ringworm
 Athlete’s Foot
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Ringworm is a skin infection caused by a fungus. Ringworm can affect
skin on your body (tinea corporis), scalp (tinea capitis), groin area (tinea
cruris, also called jock itch), or feet (tinea pedis, also called athlete's
foot).
Often, there are several patches of ringworm on your skin at once.
Parasites – Single-celled or
multicellular organisms that feed off of
living things causing them harm
Malaria (Caused
by a protist
called
Plasmodium)
 Leeches
 Tapeworms
 Heartworms
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Malaria is a mosquito-borne infectious disease of humans and other animals
caused by protists (a type of microorganism) of the genus Plasmodium. It
begins with a bite from an infected female mosquito, which introduces the
protists via its saliva into the circulatory system, and ultimately to the liver
where they mature and reproduce.
CANCER- Group of diseases
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CANCER is
caused by
genetic changes
that can occur
within the cells
of a tissue or
organ resulting
in uncontrolled
cell growth
LIVER CANCER on the right
LUNG CANCER on the right
The Immune System….
Humans have many ways to protect themselves from
danger and disease…..
* Our SENSES (eyes, ears, sense of smell)
can help detect danger
* We can release HORMONES
(Adrenaline) to help our MUSCLES
respond to danger (FIGHT OR
FLIGHT)
SKIN
BODY FLUIDS
* Unbroken SKIN keeps out
foreign organisms that could
be HARMFUL
Fluids in the body such as
* TEARS
* SALIVA
* OTHER BODY
SECRETIONS, like
Sweat, trap and
destroy invaders
* The skin acts as a barrier,
blocking pathogens much like
a wall around a Castle
protects against invaders.
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The NERVOUS system provides rapid
coordination of our body to danger.
* Senses (Detect Danger)
* Nerves in Muscles (Respond to Danger)
* Signals to Endocrine Glands (Secrete
Hormones)
THE HUMAN BODY NEEDS AN
EFFECTIVE WAY TO….
COMBAT or FIGHT OFF
invaders or body cells that
malfunction.
The IMMUNE SYSTEM is the
body’s primary defense against
DISEASE-CAUSING
PATHOGENS.
Foreign substances that threaten
HOMEOSTASIS can usually be
identified by molecules on their
outer surfaces. These molecules are
called ANTIGENS, and they trigger
(start) a response from the Immune
System.
Antigen-Antibody Diagram
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The body will make
ANTIBODIES to
fight off the
ANTIGENS. The
antibodies are
SPECIFIC to the
SHAPE of the antigen
and will FIT in to
deactivate the
antigen.
White Blood Cells can
ENGULF PATHOGENS
WBC’s SURROUND the bacteria
and then “eat” it by releasing
digestive enzymes which kill the
bacteria.
White Blood Cells can MAKE
ANTIBODIES TO DESTROY
ANTIGENS
The WBC is making
ANTIBODIES that can attack
the invader or mark them for
KILLING
How WBC’s Fight Pathogens
Some specialized WHITE BLOOD CELLS will
remain in the body long after the
pathogen is gone.
These “Memory” cells will divide QUICKLY
and produce more antibodies if they come
in contact with that pathogen again.
ANTIBODIES are effective against microbes
(microscopic organisms) that appear
YEARS later.
Vaccinations
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Scientists have discovered that weakened
MICROBES can stimulate (start) the
Immune System to REACT (respond).
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Vaccines are made by using WEAKENED,
Killed (dead), or Parts of MICROBES.
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When vaccines are injected into the
BODY, the Immune System responds just
as if it were invaded by a LIVE pathogen
and will produce ANTIBODIES.
After a vaccination, the Immune
System….
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REMEMBERS the specific pathogen
by leaving behind special WHITE
BLOOD CELLS that will protect the
body for years!
Making a Vaccine
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Obtain the PATHOGEN
Treat pathogen to KILL or WEAKEN it
Inject the pathogen (VACCINE) into the
organism
The body responds by making
ANTIBODIES and having the WBC’s
ATTACK the invader
Some WBC’s SPECIFIC for this pathogen
remain in the body for a long time to
continue PROTECTION from future
attacks.
DAMAGE/PROBLEMS ASSOCIATED WITH THE
IMMUNE RESPONSE
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The immune system may weaken with AGE or
other factors like STRESS, fatigue. This can
make us more VULNERABLE to disease.
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Some viral diseases like AIDS result from an
attack on the IMMUNE system. The damage
leaves the person UNABLE to deal with
infections and CANCEROUS cells.
A WEAKENED immune system is one reason people with AIDS die of
INFECTIONS that a healthy person could fight off.
ALLERGIES
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An ALLERGY is a rapid immune response to
substances that are usually harmless.
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Certain FOODS, pollen, and chemicals from
INSECT bites are examples of things that
can cause an allergic reaction.
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In an allergy, the body releases chemicals
called HISTAMINES which can lead to a
RUNNY nose, SNEEZING, rashes, and
SWELLING.
People with allergies often use…
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ANTI-HISTAMINES to reduce their
symptoms.
AUTOIMMUNE DISEASE
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Sometimes the immune system
malfunctions and fails to recognize “SELF”
molecules and attacks the body’s own
cells.
 Lupus
 Rheumatoid Arthritis
 Juvenile Onset Diabetes
ORGAN TRANSPLANTS
Since a transplanted organ comes from
ANOTHER person, the immune system
recognizes it as an INVADER and may
start to attack the new organ.
 To avoid REJECTION, transplant patients
receive special drugs to suppress their
IMMUNE system. This may leave the
patient ILL from a pathogen that would
normally be no threat.
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