What is the difference between arteries, veins, and capillaries?

Arteries, veins, and capillaries are three types of blood vessels that differ in their structure and function within the circulatory system. Arteries carry blood away from the heart, veins carry blood towards the heart, and capillaries allow the exchange of materials between blood and body tissues.

Arteries have thick, muscular, and elastic walls because they carry blood under high pressure. Most arteries transport oxygen-rich blood, except the pulmonary artery.

Veins have thinner walls and contain valves that prevent the backward flow of blood. Most veins carry oxygen-poor blood, except the pulmonary vein.

Capillaries are the smallest blood vessels with very thin, one-cell-thick walls. They connect arteries and veins and help exchange oxygen, carbon dioxide, nutrients, and waste products between blood and cells.

Together, these blood vessels maintain circulation and support the proper functioning of body systems.