Certified Ophthalmic Medical Technologist (COMT) Practice Exam

Which mechanism do adrenergic antagonists primarily affect?

1. Promoting vasodilation

2. Blocking adrenergic receptors

3. Enhancing neurotransmitter release

4. Inhibiting acetylcholine secretion

The correct answer is: Blocking adrenergic receptors

Adrenergic antagonists, also known as beta-blockers and alpha-blockers, primarily work by blocking adrenergic receptors in the body. These receptors are part of the sympathetic nervous system and are activated by neurotransmitters such as adrenaline (epinephrine) and noradrenaline (norepinephrine). When these receptors are blocked, the effects of adrenergic stimulation are inhibited, leading to various physiological outcomes. For instance, blocking beta-adrenergic receptors can help reduce heart rate and lower blood pressure, while blocking alpha-adrenergic receptors can lead to vasodilation. The other choices present mechanisms that are not directly associated with the primary action of adrenergic antagonists. Promoting vasodilation can occur as a result of blocking alpha receptors but is not the primary action. Enhancing neurotransmitter release typically involves adrenergic agonists instead, which stimulate receptors rather than blocking them. Inhibiting acetylcholine secretion is more related to cholinergic mechanisms and does not involve adrenergic receptors. Thus, the primary mechanism by which adrenergic antagonists act is indeed through the blockade of adrenergic receptors.