Question

Which of the following physiologic actions does epinephrine produce when given for an allergic reaction?

1) Bronchodilation and vasodilation
2) Vasoconstriction and bronchodilation
3) Bronchoconstriction and vasoconstriction
4) Blocking of further histamine release

Answer 1

Epinephrine causes vasoconstriction and bronchodilation when given for an allergic reaction, ultimately increasing blood pressure and improving breathing by relaxing bronchial smooth muscles.

Step-by-step explanation:

The physiologic actions that epinephrine produces when given for an allergic reaction are vasoconstriction and bronchodilation. During an allergic reaction such as anaphylaxis, epinephrine is crucial as it increases blood pressure through vasoconstriction, while also relaxing the bronchial smooth muscle (bronchodilation) to improve breathing.

Epinephrine interacts with both α (alpha) and β (beta)-adrenoreceptors, which control these processes. The reaction overrides the vasodilation mediated by β-adrenoreceptors, primarily causing vasoconstriction which helps to raise blood pressure that often drops during severe allergic reactions. The bronchodilation effect is vital for alleviating symptoms like shortness of breath and wheezing by opening the airways, making it easier to breathe.