Biology · Human Health and Diseases · NEET
IgE. NCERT clearly says the antibodies produced against allergens are of the IgE type. This is a very common NEET one-liner: allergen enters, body makes IgE, IgE sits on mast cells. Do not write IgG or IgM for allergy.
Because the immune system reacts too strongly to harmless things. NCERT defines allergy as the exaggerated response of the immune system to certain antigens present in the environment. Pollen, mites and dander are not real dangers, but the body still fires a big IgE response, causing sneezing and wheezing.
Mast cells. NCERT: allergy is due to the release of chemicals like histamine and serotonin from the mast cells. When IgE-coated mast cells meet the allergen, they burst open and release histamine and serotonin, which cause the symptoms. Remember: Mast cells = the chemical store.
Every allergen is an antigen, but not every antigen causes allergy. An allergen is a special antigen (like dust mite, pollen, animal dander) that triggers an exaggerated IgE response. NCERT calls the substances that cause this response allergens. So allergen = allergy-causing antigen.
Yes, asthma is an allergic (hypersensitivity) reaction. It happens due to the allergic reaction of mast cells in the lungs. The IgE-mast cell reaction in the airways releases histamine, causing the airways to narrow, giving wheezing and difficulty in breathing. NEET 2016 asked exactly this.
NCERT lists three: anti-histamine, adrenalin, and steroids. These quickly reduce the symptoms. Anti-histamine works by blocking histamine, which is the main chemical causing the symptoms. Memory: to fight histamine, use ANTI-histamine.
Asthma may be attributed to:
Match List I with List II: A. Common cold B. Haemozoin C. Widal test D. Allergy | I. Plasmodium II. Typhoid III. Rhinoviruses IV. Dust mites
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Allergy is when the immune system reacts too strongly to a harmless substance in the environment. NCERT calls it the exaggerated response of the immune system to certain antigens (allergens) like pollen and dust mites.
NCERT gives these examples: mites in dust, pollens, and animal dander. These enter the body and make it produce IgE antibodies.
Sneezing, watery eyes, running nose, and difficulty in breathing. These are caused by histamine and serotonin released from mast cells.
NCERT: the patient is exposed to or injected with very small doses of possible allergens, and the reactions are studied. This is the skin-test method.
Histamine is the main chemical that causes allergy symptoms. Anti-histamine blocks histamine, so the symptoms reduce quickly. NCERT also lists adrenalin and steroids as drugs that reduce allergy symptoms.
NCERT says modern lifestyle has lowered immunity and increased sensitivity to allergens. This may be because of the very clean, protected environment given early in life, so the immune system does not learn to ignore harmless particles.
