Allergy

Definition

An allergy is an exaggerated immune response to a substance that is typically harmless to most people, known as an allergen. This hypersensitivity reaction involves the immune system overreacting, causing symptoms that can range from mild to severe.

5 Must Know Facts For Your Next Test

1. Allergies are classified as Type I hypersensitivities and are mediated by IgE antibodies.
2. Common allergens include pollen, pet dander, certain foods, and insect stings.
3. Mast cells and basophils play a crucial role in allergic reactions by releasing histamine and other inflammatory mediators.
4. Symptoms of allergies can include itching, swelling, hives, respiratory issues, and anaphylaxis in severe cases.
5. Epinephrine is commonly used as an emergency treatment for severe allergic reactions or anaphylaxis.

Review Questions

• What type of hypersensitivity reaction is an allergy classified under?
• Which immunoglobulin is primarily involved in allergic reactions?
• Name three common allergens and describe their potential effects on the body.

Related terms

Hypersensitivity: An excessive or inappropriate immune response to an antigen.

Anaphylaxis: A severe, potentially life-threatening allergic reaction that occurs rapidly.

Histamine: A compound released by mast cells during allergic reactions that causes vasodilation and increased permeability of blood vessels.