Medical Laboratory Scientist (MLS) ASCP Practice Exam

Angiotensin II plays a crucial role in the regulation of blood pressure and fluid balance. It is primarily known for its potent vasoconstrictive effects, meaning it causes blood vessels to narrow. This narrowing increases vascular resistance, leading to an increase in blood pressure. In addition to its vasoconstrictive properties, angiotensin II stimulates the release of aldosterone from the adrenal glands, which promotes sodium and water reabsorption in the kidneys. This action further contributes to elevating blood volume and blood pressure as well.

While other options include actions associated with cardiovascular function, they do not accurately represent the primary effect of angiotensin II. For example, decreased blood pressure and increased vasodilation are contrary to the established actions of this hormone. Similarly, a decrease in heart rate is not directly influenced by angiotensin II; rather, its major action involves increasing systemic vascular resistance through vasoconstriction, making this the correct choice.