Transcript Allergic reactions

What is an allergy?
Allergic symptoms
Example of allergies
Example of allergens
How body responds
to allergens?
Allergies
A rapid overeaction to an antigen that is not normally harmful
Allergens: substances that cause allergic reactions.
Examples
Pollen
Insect sting
Body cells
release
Certain food
Animal hair
HISTAMINE
Dust
Mold
INFLAMMATORY
RESPONSE
SYMPTOMS
runny nose
swollen eyes
wheezing
rash
coughing
Antihistamines: drugs used to counteract the effects of histamine
Mast Cells and the Allergic Response
What is allergy?
Example of allergens
A rapid overraction to an antigen that is not
normally harmful
Pollen, Mold, Dust, Certain food, Animal hair
How does body respond
to allergens?
The body cells release histamines,
which cause an inflammatory response
and many allergic symptoms
Allergic symptoms
runny nose, swollen eyes, wheezing, rash,
coughing, itching
Example of allergy?
Asthma
Allergies
The immune system helps maintain the internal dynamic equilibrium necessary for life.
However, the immune system can become out of balance.
Allergic reactions result form over activity of the immune system. The body responds
inappropriately to common substances such as dust, mold, pollen, or certain foods. Antigens
that cause allergic reactions are called allergens.
The immune system begins making a special type of antibody to these substances, which
under normal conditions would not stimulate the immune system.
These antibodies cause cells in the body to release histamines, which cause many allergic
symptoms, such as extra fluid in the nasal pathways, difficulty breathing, or inflammation.
Allergies are often treated with antihistamines, drugs that stop the release of histamine.
Some allergic reactions can create a dangerous condition called asthma. Asthma is a chronic
respiratory disease in which the air passage become narrower than normal.
This narrowing of the air passage causes wheezing, coughing, and difficulty in breathing.
Many factors, including both heredity and environment, play a role in the onset of the
symptoms of asthma.
Asthma attacks can be triggered by respiratory infections, exercise, emotional stress, and
certain medications, cold air, pollen, dust, tobacco smoke, pollution, etc..
Allergies – 10% of US population
 Many small molecules (called haptens
or incomplete antigens) are not
antigenic, but link up with our own
proteins
 The immune system may recognize and
respond to a protein-hapten
combination
 The immune response is harmful rather
than protective because it attacks our
own cells
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
Allergic symptoms
Example of allergens
What is an allergy?
Example of allergies
How body responds
to allergens?