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Unit 11 – Immunity
Guided Notes
The Fight Against Infection
Where do diseases come from?
Years ago…
Now…
People believed they got
diseases from evil
spirits and spells!
People now know diseases
come from
microorganisms and
viruses!
Remember Redi and
Pasteur’s experiments??!!
Redi & Pasteur
Redi’s Experiment
He took 2 glass jars and
placed meat inside each
one; one was covered
and one was uncovered
After a few days the
uncovered meat had
maggots; the covered
one did not
Redi disproved
spontaneous generation
Pasteur’s Experiment
He put broth into two curved flasks
He heated one flask to boiling; the
other flask he did not boil
After a few days, the unboiled broth
was cloudy showing bacteria was
generated from bacteria already
present
The boiled flask had no new bacteria
growth because it had been killed
Redi & Pasteur continued…
Once scientists knew that
disease was caused by bacteria,
viruses, and microorganisms
(and not spells) they could begin
to study immunity more
efficiently.
So what is IMMUNITY?
Definition:
- the ability of the body’s blood to defend against
infection
- our immune system protects us from pathogens
(any organism/protein-structure that cause disease)
- in fact, our immune system is what helps us recognize
pathogens as foreign objects so we can destroy them
Causes of Disease
1.
Viruses: tiny particles made of a protein shell
that invade cells and make the cell replicate
(double) their genetics; they can look like
spiders with legs; have receptors on surface
2.
Bacteria: small microorganisms that either
breakdown the tissue of the organism or
release toxins
3.
Worms, Protists, and Fungi: they are all agents
that invade the host causing damage or even
death; they live off of what they are inside/on
Causes of Disease
1.
Viruses
- NOT cells (can’t reproduce); not living
- attach to the cell
- inject their genes (DNA or RNA)
- cell makes more viruses
- have “antigens” on surface
(fit to body cell receptors like a lock and key)
Causes of Disease
2.
Bacteria
- tiny, one-celled organisms; living (can do life processes)
- most are GOOD for you (90%); bad ones treated with
antibiotics
- found in yogurt, cheeses, butter, sauerkraut, pickles, olives, soy
sauce
- also have “antigens” on surface; our bodies attack these with
“antibodies”
Three types:
bacilli = rod shaped
cocci = circle shaped
spirilla = spiral shaped
Examples
DISEASES CAUSED BY
VIRUSES
DISEASES CAUSED BY
BACTERIA
Genital herpes
strep throat
HIV
Food borne illness by E. Coli
cold sores (oral herpes)
tuberculosis
Influenza (flu)
anthrax
West Nile
Botulism
pneumonia
How Are Diseases Spread?
Physical contact - touching, sexual contact,
coughing, sneezing, not washing hands
Contaminated Food and Water undercooked meat, untreated water,
unrefrigerated food
Infected Animals - mosquito, rabid animals,
fleas (Bubonic Plague of Europe; caused by
fleas carried on rats in poor sanitation
conditions)
Body’s Way to Prevent Disease
1.
Skin - hard to penetrate (pass through) the layers
of dead skin; enzymes in our secretions break
down bacteria’s membrane killing them
2.
Inflammatory response - a nonspecific defense
reaction to tissue damage caused by injury or
infection (any health problem caused by a disease
producing organism)
3.
Immune response - the body’s specific defenses
that attack a pathogen using the antibody/antigen
attack
Line of Defense # 1
Skin
- many layers of dead skin keep pathogens out
-
blood clots and white blood cells at cut sites
often prevent infection
-
Pus and redness often indicate the skin has
become infected
An infected toe nail; note
the redness and infection
Line of Defense # 2
Inflammatory Response (non-specific)
-
activated when pathogens enter the body and trigger the
release of chemicals called histamines
-
histamines cause the capillaries to swell by increasing blood
flow to exposed areas and increase mucus production
-
See body areas become inflamed or swollen ex. Bee sting,
pollen
-
Interferons: cells that make a protein for other cells so they
resist viral infection; block viral replication (almost like
choking them)
-
The inflammatory response can indicate an allergy
Inflammatory Response
continued
allergies- the body’s
overreaction to
antigens
antigens that cause
allergic reactions are
called allergens
common allergens
include ragweed
pollen, dust, dust
mites
Line of Defense # 3
Immune Response (specific)
Activated when other defenses do not work
Triggered by an antigen (on the surface of foreign
substances that invade the body & cause disease)
White blood cells recognize these antigens and
release antibodies (proteins that stick to antigens);
after “sticking” to the antigen, the antibodies
trigger white blood cells to attack the antigen,
destroying it
Line of Defense # 3 continued
Certain white blood cells called memory B cells can
remember specific antigens and are able to fight these
antigens the next time they infect the organism
This is why you do not get Chicken Pox twice!
Your body fights it the first time, makes antibodies
against that specific disease, and you get well; if you
come around Chicken Pox again, your memory B cells
“remember” the disease, already know how to make the
antibodies to fight it, and you do not get sick again
Line of Defense # 3 continued
Review: Jobs of a White Blood Cell
1. Tag and recognize foreign objects
2. Engulf (phagocytes) and/or destroy
bacteria/viruses/old cells
3. Make antibodies
Recognize
and tag…
Engulfing…
Immune Response continued
Immune Response
Passive Immunity
-Temporary (short term)
- type of immunity that
develops from being given
antibodies through
injection
Ex. mother’s milk; through
placenta (diffusion of
antibodies to baby from
mother)
Active Immunity
-long term
- type of immunity from the
body having the disease
once, making antibodies,
and recognizing it in the
future
- also includes vaccinations
Immune Response continued
More on Active Immunity
Vaccination (process of injecting a
weakened/inactive form of a
pathogen to produce immunity)
Weak pathogen triggers antibody
production; so now when you get
infected with the “active” form of the
disease, you have antibodies ready
More than 20 serious human diseases
can be prevented by vaccination
Ex. Polio, measles, mumps, chicken
pox, flu
Vaccinations continued…
Vaccines “jump start” your immune
system; gives you a head start on
beating the disease
Getting a vaccine increase the ability to
fight a pathogen because you make
antibodies against the pathogen’s
antigens
Diseases
When the body is unable to fight off a pathogen, a
failure in homeostasis occurs and the organism
develops a disease; organism can become ill or
even die!!!
In some cases, when the immune system makes a
mistake and attacks the body’s own cells, it is
called an autoimmune disease
Autoimmune Diseases
In autoimmune diseases,
the body produces
“antiself” antibodies
These “antiself”
antibodies are sent out to
destroy the organism’s
own body tissues
Ex. Multiple Sclerosis
(MS), Type I Diabetes
2050: Finally mad enough to act, the Earth
makes antibodies against the human race
AIDS - An Immunodeficiency
Disease
AIDS is not an autoimmune disease
AIDS is considered an immunodeficiency
disease because a virus destroys certain
white blood cells in the body so that the
immune system does not work properly
AIDS is caused by the virus HIV; leaves the
body with no protection to fight other
diseases
AIDS continued
Most AIDS patients die
from another minor
infection
AIDS can be transmitted
through sexual intercourse,
shared needles, contact with
infected blood, and through
child birth including breastfeeding
AIDS cannot be transmitted
by sitting next to someone!
Ways to Prevent Disease
Your body has numerous responses to
prevent disease:
skin
sneezing
coughing
stomach acid
How to avoid communicable
(passable) diseases and stay healthy?
Wash your hands many times a
day using soap
Live in a clean house: change
sheets regularly, eliminate carpet,
use antibacterial cleaners
Yawn, cough, and sneeze into the
crutch of your elbow
Use a tissue to blow your nose and
throw it away
Avoid touching bathroom door
handles when leaving bathrooms
Diseases of Interest
1.
Leukemia - form of cancer associated with high number of
white blood cells; treated with chemotherapy/radiation
2.
Polio – contagious disease caused by a virus that affects the
nervous system; vaccine required
3.
Lupus – an autoimmune disease where the body attacks its
own tissues causing joint pain, heart problems, and even
iron deficiencies (anemia); no cure
4.
Multiple Sclerosis (MS) – an autoimmune disease where
nerve cells of the body are attacked causing pain, loss of
balance, slurred speech, and tremors; no cure