Which of the following best explains the role of capillaries in the circulatory system?

The role of capillaries in the circulatory system is fundamentally to facilitate the exchange of nutrients, gases, and waste products between the blood and surrounding tissues. Capillaries are the smallest and most numerous blood vessels in the body, creating an extensive network that connects arteries and veins. This configuration allows for an efficient transfer of oxygen, carbon dioxide, glucose, and other substances between the blood and the cells of the body.

The thin walls of capillaries, composed of a single layer of endothelial cells, enable these exchanges to occur rapidly. Oxygen and nutrients can diffuse out of the blood into the tissues, while carbon dioxide and metabolic wastes move from the tissues into the blood. This exchange is crucial for maintaining homeostasis and ensuring that cells receive the materials they need for metabolic processes.

In contrast, other options describe different functions that are not directly associated with capillaries. Blood transport away from the heart relates primarily to arteries, while blood pressure regulation is managed by larger arteries and arterioles. Additionally, while oxygen is carried in the blood, it is not stored in capillaries; rather, hemoglobin in red blood cells binds oxygen for transport. Thus, the connection of capillaries to arteries and veins for nutrient exchange accurately captures their