Final answer:
Anaphylactic shock occurs when histamines are released in response to an allergen, leading to vasodilation and a potential drop in blood pressure. Epinephrine is the primary treatment as it counteracts these effects and can be life-saving.
Step-by-step explanation:
Anaphylactic shock can result after allergic reactions due to widespread release of histamines, which triggers vasodilation. When an allergen is encountered, systemic mast cell degranulation occurs, releasing histamines and causing a variety of symptoms including a dangerous drop in blood pressure, constriction of bronchial smooth muscle, and potentially respiratory distress. To counteract these effects, epinephrine is used as it raises blood pressure, relaxes bronchial muscles, modulates heart rate, and helps to reduce swellings, such as swelling of the tongue and throat that can obstruct the airway.