Final answer:
The direct answer to the action caused by epinephrine in anaphylaxis is B )
vasoconstriction. It helps by increasing blood pressure which is essential for treating the severe allergic reaction, and contrary to causing bronchoconstriction or decreased heart rate, it helps improve breathing and modulates heart rate.
Step-by-step explanation:
The correct action of epinephrine in anaphylaxis is B. Vasoconstriction. In response to an allergic reaction, epinephrine constricts the blood vessels to help increase blood pressure, counteracting the drop in blood pressure seen in anaphylaxis.
During anaphylaxis, a severe allergic reaction, the body releases large amounts of histamines leading to symptoms such as a drop in blood pressure and swelling of the throat. Epinephrine, commonly administered through an autoinjector like an EpiPen®, acts quickly to mitigate the effects of anaphylaxis by constricting blood vessels which increases blood pressure, and by relaxing smooth muscles in the lungs to improve breathing. It does not cause bronchoconstriction or decrease heart rate; it actually facilitates bronchodilation and can modulate the heart rate to help the patient in anaphylactic shock. Therefore, the actions of epinephrine during anaphylaxis include vasoconstriction and bronchodilation, vital for reversing the life-threatening symptoms of anaphylaxis.