The nurse administers a drug to a patient whose heart rate is bradycardic aimed at increasing heart rate and myocardial activity. What adrenergic receptor is this drug stimulating?
Explanation & Rationale
A) Beta 1: Beta-1 adrenergic receptors are primarily located in the heart and are responsible for increasing heart rate (chronotropy), the force of contraction (inotropy), and the conduction speed of electrical impulses within the heart (dromotropy). When a drug is given to increase heart rate and myocardial activity, it is stimulating the beta-1 receptors, which enhance the heart's performance.. B) Beta 2: Beta-2 receptors are predominantly found in smooth muscles, such as those in the bronchi, blood vessels, and uterus. Stimulation of beta-2 receptors leads to relaxation of these muscles, including bronchodilation and vasodilation, which would not have a direct effect on increasing heart rate or myocardial activity. C) Alpha 2: Alpha-2 receptors are primarily located in the central nervous system (CNS) and act to inhibit the release of norepinephrine, leading to a reduction in sympathetic nervous system activity. They have the opposite effect of what is desired in this case, as stimulation of alpha-2 receptors would actually lower heart rate and decrease myocardial activity, not increase it. D) Alpha 1: Alpha-1 receptors are found in the smooth muscle of blood vessels and when stimulated, cause vasoconstriction, which increases blood pressure. While alpha-1 receptors do affect the cardiovascular system, they do not directly influence heart rate or myocardial contractility.