What is allergy? Explain.

(N/A) Allergy is the exaggerated response of the immune system to certain antigens present in the environment.
Key points regarding allergy:
$1$. The substances to which such an immune response is produced are called allergens.
$2$. The antibodies produced in response to allergens are of the $IgE$ type.
$3$. Common examples of allergens include mites in dust,pollens,and animal dander.
$4$. Symptoms of allergic reactions include sneezing,watery eyes,running nose,and difficulty in breathing.
$5$. Allergies are caused due to the release of chemicals like histamine and serotonin from the mast cells.
$6$. To determine the cause of an allergy,the patient is exposed to or injected with very small doses of possible allergens,and the reactions are studied.
$7$. The use of drugs like anti-histamine,adrenaline,and steroids quickly reduces the symptoms of allergy.
$8$. Modern-day lifestyle has resulted in lowering of immunity and more sensitivity to allergens,leading to increased incidence of allergies and asthma,especially in children in large cities due to over-protected environments.