Q.While on an excursion to a hill station, some of the children developed allergic symptoms.

Concept: Allergy – hypersensitivity of the immune system to harmless environmental substances (allergens), triggering histamine release and characteristic symptoms.

(a) Two allergic symptoms:

When allergens bind to IgE antibodies on mast cells, histamine and other mediators are released, causing inflammation and tissue responses. Common manifestations include:

1. Sneezing and runny nose (allergic rhinitis)
2. Watery, itchy eyes (allergic conjunctivitis)

Other examples: skin rashes, difficulty breathing, or swelling.

(b) Two allergens:

Allergens are typically proteins or glycoproteins from the environment. At a hill station, likely triggers are:

1. Pollen grains (from flowering plants)
2. Dust mites (in bedding or upholstery)

Other examples: animal dander, mold spores, certain foods.

(c) Two antiallergens (antihistamines/treatments): …

Understanding Allergies

An allergy is an exaggerated immune response to substances that are typically harmless to most people. When the immune system mistakenly identifies a benign substance as a threat, it triggers a cascade of reactions involving antibodies (particularly IgE), mast cells, and histamine release. This histamine is responsible for most allergic symptoms.

At a hill station, children are exposed to new environmental triggers—pollen from unfamiliar plants, different dust compositions, cooler air that may carry mold spores, or even insect proteins. The immune system of a sensitized individual overreacts to these allergens, producing the characteristic symptoms we associate with allergies.

(a) Two Allergic Symptoms

When histamine and other inflammatory mediators are released during an allergic reaction, they affect various tissues:

1. Sneezing and runny nose (rhinitis): Histamine irritates the nasal mucosa, causing inflammation, increased mucus production, and the reflex action of sneezing to expel the perceived irritant.

2. Watery, itchy eyes (conjunctivitis): The conjunctiva becomes inflamed and blood vessels dilate, leading to redness, excessive tearing, and itching.

Other common symptoms include skin rashes (urticaria or hives), difficulty breathing (in asthma-like responses), and in severe cases, anaphylaxis.

(b) Two Allergens

Allergens are the antigens that trigger allergic reactions. At a hill station, likely culprits include:

1. Pollen grains: Released by flowering plants and trees, these microscopic particles are easily inhaled. Hill stations often have different vegetation than plains, exposing visitors to novel pollen types.

2. Dust mites: These microscopic arachnids thrive in bedding, upholstery, and carpets. Their fecal pellets and body fragments are potent allergens, particularly in enclosed spaces like hotel rooms.

Other common allergens include mold spores (thriving in damp, cool environments), animal dander, certain foods (nuts, shellfish), and insect stings.

(c) Two Antiallergens (Antiallergic Drugs) …