Small blood vessels, also known as small veins, are small tubes that carry blood throughout the body. Small blood vessels include arterioles, capillaries, and venules. Small arteries take oxygenated blood away from the heart and take it to the capillaries.

Capillaries are the smallest blood vessels in the body where gas exchange between blood and tissues takes place. Veins are small veins that collect deoxygenated blood from capillaries and return it to the heart.

Together, these small blood vessels play an important role in maintaining proper blood circulation and delivering oxygen and nutrients to all parts of the body. :

https://www.healthdirect.gov.au/blood-and-blood-vessels