What is the main function of capillaries in the circulatory system?

The main function of capillaries in the circulatory system is to allow gas and nutrient exchange. Capillaries are the smallest blood vessels in the body, and their walls are incredibly thin, consisting of only a single layer of endothelial cells. This structural characteristic facilitates the diffusion of oxygen, carbon dioxide, nutrients, and waste products between the blood and surrounding tissues.

In this exchange process, oxygen and nutrients from the blood are delivered to cells, while carbon dioxide and metabolic waste products are collected from the cells to be transported back into the bloodstream. Because of their extensive network throughout the body, capillaries are critical in ensuring that all tissues receive the necessary substances for cellular metabolism, contributing to overall homeostasis.