Advanced Dental Admission Test (ADAT)

What is the effect of B2 adrenergic receptors on blood vessels?

1. Vasoconstriction

2. Vasodilation

3. Group contraction

4. Enhanced fluid retention

The correct answer is: Vasodilation

B2 adrenergic receptors primarily mediate vasodilation in blood vessels. When stimulated by catecholamines such as epinephrine, these receptors induce a relaxing effect on the smooth muscle layer of blood vessels, particularly in skeletal muscle and the coronary circulation. This vasodilation increases blood flow to these areas during the fight-or-flight response, contributing to the body's ability to respond to stress. The presence of B2 adrenergic receptors is significant as they counteract the effects of alpha-1 adrenergic receptors, which are associated with vasoconstriction. The net effect of B2 stimulation is thus the widening of blood vessels, leading to lower resistance and enhanced blood flow. Other options, such as group contraction or enhanced fluid retention, relate to different physiological responses and do not correctly represent the specific function of B2 adrenergic receptors in the context of blood vessels. While vasoconstriction is a function linked to other adrenergic receptor types, it is not the role of B2 adrenergic receptors in vascular physiology.