Final answer:
The pulmonary effects of β2-adrenergic stimulation include bronchodilation and decreased bronchial secretions, which are the result of the relaxation of smooth muscles in the bronchi and a reduction in mucus production, respectively.
Step-by-step explanation:
The pulmonary effects of β2-adrenergic stimulation include two specific actions: bronchodilation and a decrease in bronchial secretions. When β2-receptors are activated, as in the case of epinephrine acting on these receptors, the result is the relaxation of the smooth muscle in the bronchi, leading to bronchodilation. This action is beneficial in conditions such as asthma, where airway constriction is a problem. Additionally, β2-adrenergic stimulation tends to decrease bronchial secretions, which can help reduce mucus production and improve airflow.
It is important to note that while epinephrine reacts with both alpha and beta adrenoreceptors, causing both vasoconstriction and vasodilation, the β2-receptor specifically, when activated by lower levels of epinephrine, causes smooth muscle relaxation in the bronchi, override any alpha-receptor mediated vasoconstriction effects in the lungs. Therefore, the two significant pulmonary effects that can be selected from the options provided are bronchodilation and decreased bronchial secretions, which correspond to options d and b, respectively.