Which of the following best describes capillaries?

Capillaries are best described as tiny vessels that facilitate the exchange of nutrients, gases, and waste products between the blood and surrounding tissues. These microscopic blood vessels connect arterioles, which carry blood away from the heart, to venules, which return blood to the heart. Because of their thin walls, which are only one cell layer thick, capillaries allow for efficient diffusion of oxygen, carbon dioxide, hormones, and nutrients into and out of cells. This unique structure is crucial for cellular metabolism and maintaining homeostasis in the body, as it ensures that every cell receives the necessary nutrients while also allowing waste products to be removed efficiently.