Transcript Disease as a Failure of Homeostasis

DISEASE AS A FAILURE OF
HOMEOSTASIS
Disease
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Any condition that prevents the body from working
as it should
As a result the body may fail to maintain
homeostasis.
Disease may result from pathogens, abnormal cells,
carcinogens, poor nutrition, inherited disorder, or
risky personal behavior
Causes of disease
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Inherited disorders – Like down syndrome, cystic
fibrosis, sickle cell anemia
Exposure to toxins/ carcinogens – lead poisoning,
radiation poisoning
Poor nutrition – scurvy (vitamin C deficiency), goiter
(iodine deficiency)
Organ Malfunction – Heart Attack, diabetes
High risk behaviors – lung cancer, drug addiction,
skin cancer
Pathogens
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Virus – particles composed of nucleic acid and
protein. They reproduce when they invade living
cells
Bacteria – are one celled organisms
Fungus – can be uni or multi cellular. Include yeasts
and molds. They eat by absorbing organic
substances.
Parasites – can be uni or multi cellular. Survive and
by living and feeding on other organisms.
Keeping Pathogens Out
Skin
 Protective barrier
 Sweat, tears, saliva
 Contains enzymes to destroy the cell
membranes of certain bacteria
 Mucous membranes
 These line internal membranes that entrap
pathogens that are then washed away or
destroyed by chemicals.
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Second line of defense
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Leukocytes – Phagocytes for short minor invasions
and lymphocytes are for longer more serious
invasions
 Phagocytes
rapidly trap, consume and completely
destroy foreign material
 The inflammatory response –
 Damaged
cells release histamine
 causes swelling, redness, warmth, and pain in the areas of
infection. The damaged cells release certain chemicals
which increase blood flow to the area.
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Macrophages are white blood cells that can ingest
large numbers of bacteria
Pus is dead cells, phagocytes, bacteria, and body
fluid.
When the pathogen is a virus, the infected cells
produce a protein (interferon) that causes nearby
uninfected cells to produces enzymes that block
reproduction of the virus.
Third line of Defense
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When the inflammatory response defense in
insufficient the pathogen is targeted for destruction
by the body’s last line – IMMUNE RESPONSE
It “remembers” each kind of pathogen that enters
the body by producing antibodies.
The immune system discriminates between different
kinds of pathogens unlike the phagocytes
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When an antigen is first introduced into your body
your system undergoes a primary immune response.
The first 5 days or so there is no detectable
antibodies or specialized immune cells. It takes
about 10 – 15 days to get a gradual increase in
these cells
Any other time that the antigen is introduced into
your system, it undergoes a more rapid secondary
immune response. Within the first day or so high
levels of antibodies and specialized immune cells
are detected.
Type of Immunity
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Active Immunity – This is when the body produces its
own antibodies to attack a particular antigen
 This
is when you get a disease and make your own
antibodies
 Some vaccinations
 Therefore – memory cells stay within your body so you
can respond to a pathogen quickly during subsequent
exposure.
Vaccinations
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Vaccination are of two types –
 Uses
dead or weakened pathogens (uses chemicals or
heat) to destroy the pathogen.
 The inactive pathogen enters the blood stream – your
immune system attacks it and makes antibodies against
it – WITHOUT getting sick – but you MADE the
antibodies ---therefore active immunity
 OR The vaccine (if pathogen is too dangerous) can be
the antibodies instead --- therefore passive immunity
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Passive Immunity – You are given antibodies from
either another person or animal
 Vaccinations
needing boosters
 Through maternal immunity (mother passes antibodies
through placenta to unborn child
 Through mothers milk
* Passive immunity is only TEMPORARY and lasts only
about a month or so because the body destroys the
borrowed antibodies.
Some Diseases
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Transplants
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Allergies
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Body makes the wrong antibodies
Leukemia
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Takes immune suppressor drugs.
Making many white blood cells that don’t work
HIV/ AIDS
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HIV is a VIRUS that kills helper T cells (the tattle tale cells
that let your body know you are sick). Therefore you can
die from getting a cold when it has become full blown AIDS
Biological Research of disease
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Research
 Control
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vs experimental groups
Diagnosing Disease
Preventing and controlling disease
Treating and curing disease