Final answer:
Anaphylaxis is a severe hypersensitivity reaction that can be life-threatening and is treated with the adrenoceptor agonist epinephrine. Epinephrine raises blood pressure, relaxes bronchial smooth muscles, and is carried by individuals with known severe allergies for emergency self-administration.
Step-by-step explanation:
Anaphylaxis is a systemic, potentially life-threatening type I hypersensitivity reaction that is triggered by allergens. These allergens are often harmless in themselves but can cause severe reactions in predisposed individuals. When an individual is exposed to an allergen, such as shellfish, peanuts, bee stings, or certain medications like penicillin, their immune system may overreact and release a vast amount of histamines. This release can lead to a rapid drop in blood pressure (shock), contractions of bronchial smooth muscle, and other symptoms such as respiratory distress and swelling of the throat, which can be fatal if not treated promptly. To treat anaphylaxis, an adrenoceptor agonist, specifically, epinephrine, is administered. This medication works by raising blood pressure and relaxing bronchial smooth muscle, helping to alleviate symptoms. Epinephrine constricts blood vessels, modulates heart rate, and reduces swelling. People with known severe allergies are advised to carry automatic epinephrine injectors, such as EpiPens, to provide immediate treatment in the event of an anaphylactic reaction.