A nurse is assessing a patient with chronic venous insufficiency. Where are the valves located in the vascular system outside of the heart, and what is their primary function?

In the veins, to prevent backflow of blood and ensure unidirectional flow toward the heart.

In the arteries, to help withstand high pressure and maintain arterial blood flow.

In the capillaries, to regulate the exchange of nutrients and waste products.

In the lymphatic vessels, to manage the flow of lymph fluid.