Allergy | Types | Factors | Treatment | Allergens | Natural Allergens - Pharmacognosy notes

Afnan August 22, 2017

Allergy Introduction

Definition:

allergy is defined as an exaggerated response by the body to an antigen which is harmless to the body.
or 
the response shown by an allergic person shown toward allergens, and the response is not present in normal non allergic individuals.the term was for the first time used by von bacquet.

Definition of allergen:

any foreign substance capable of sensitizing the body in such a way that an unusual response is produced in hypersensitive person.

Explanation of allergy:

allergic responses are literally spotted by the fact that similar allergic response must not be present in other normal individuals.
allergies can appears at any time or age throught life.
for a person to be allergic its not necessary for him to be allergic since his child hood,as allergic response do develop with time.here in two topics are worth a view.
  • primary exposure: its when the body encounters allergen for the first time. upto this stage allergy is not yet developed fully,because antibodies associated with that particular antigen has not yes reached the threashold to trigger the allergic response.
  • secondary exposure: the onward successive exposures of the body to allergens comes under secondary exposure.the antigens (allergen) mimic the production of antibodies upto a level that the threshold is reached.it is a stage where allergic signs and symptoms can be found in the allergic individual.

Factors behind allergy development:

following are some of the causative reasons behind the fact that why some people develop allergy while the normal population do not develop it.
  • emotional factors:a person may have an inner dislike for something that can develop into allergy.
  • atmospheric factor:atmosphere are not the same for all human population,thats why allergies developed are different
  • chronic infection:an actual infection may be mistaken as allergy
  • psychomatic factor:the illness when an emotional factor produces physical symptoms.this can arise due to over activity of autonomic nervous sytem that is influenced by emotional state.an example is a chronic blush at the feel of guilt.
  • route of exposure: a same allergen may cause allergy in one route and not in the other.for example an allergen which is inhalant cannot cause allergy if it is ingested or just by contact.
the allergic response also varies with persons condition like his age,sex,emotional state etc.

Genetic factor of allergy:

allergies are thought to be heritable means they can get from parents to their offspring however the ambiguity still exist here because offsprings are not necessary to acquire the same allergy as their offsprings.
following are some percentages of the offspring developing allergies to their allergic parents.
  • if one parent allergic: 25-50 % change that offspring develop allergy.
  • if both parents are allergic: 70-75 % chance that offspring will develop allergy.
  • if no parent is allergic: 15% chance.(this is not a heritable one.)

Types of allergies:

the allergies depends upon their allergens.the allergens directly determines which allergy will be developed on exposure.following are the types of common allergens.

Allergens classification:

Most of the allergens are natural allergens.
allergens can be divided into the following classes.
  • Inhalant allergens:they cause allergy when inhaled.an example is that of pollen allergy,dust allergy etc.the allergic reaction are accompanied by lacrimation,coughing,sneezing,runny nose etc.
  • Ingestant allergens:these allergens cause allergy if ingested.the developed allergy can be in the form of any ailment of alimentary canal like diarrhoea,constipation,abdominal pain,indigestion etc.an example is that of indigestion some people experience with milk or egg.
  • ingectant allergens: allergy will be developed if the allergen is ingected.this includes various drug allergies.
  • Contactant allergens: as the name indicate the allergic response will appear on contact with the allergen.the allergic response is often in the form of skin rashes etc.
  • infestant allergens: these allergens comes from common parasites of humans and some other insects, like roaches,ants mosquitoes beetles etc.
  • infectant allergens: when there is some microbial infection in the body.some of the metabolites of the microbes can serve as the allergen.

Cure and Remedy:

for allergy no exact cure has been discovered so form in the form of any medicine or drug.the remedy is often a symptomatic one.and various drugs that can give relief from the symptoms are administered,like antihistamines, analgesics etc.
However desensitization has been found effective in fighting allergies.

what is desensitization:

In desensitization the body is made used to when then allergen.for this purpose a very minute amount of the allergen is given each time and the dose is gradually increase.finally a stage is reached that body will not show any allergic symptoms on normal exposure of the allergen.this means that the body has adopted itself to the allergic antigen.in other words the abnormal immune response has been desensitized.

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natural allergens
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