What term describes a disorder in which the immune system is overly sensitive to a foreign substance?

• A. Allergy
• B. Acne
• C. Blood pressure
• D. Gum disease

Answer: (A)

An allergy is an immune system overreaction to a substance that is typically harmless, called an allergen. In this situation, the body's defenses respond as if the allergen were a real threat. This can involve producing specific antibodies (IgE) and releasing chemicals like histamine when exposure occurs again, leading to symptoms such as sneezing, itchy or watery eyes, runny nose, hives, or swelling. In more severe cases, an allergic reaction can impair breathing or cause anaphylaxis.

This concept helps distinguish allergies from other terms. Acne is a skin condition caused by clogged pores and bacteria, not an immune overreaction to a benign substance. Blood pressure is a measure of the force of blood against artery walls, unrelated to immune responses. Gum disease is an infection of the gums, not the result of an overreactive immune response to a harmless external substance.