What are the main kinds of blood vessels and what functions do they preform?

Arteries:

* Carry oxygenated blood away from the heart to the rest of the body

* Have thick, elastic walls to withstand the high pressure of blood being pumped from the heart

* Narrow as they branch away from the heart, creating resistance to blood flow and helping to maintain blood pressure

Veins:

* Carry deoxygenated blood back to the heart from the rest of the body

* Have thinner walls than arteries, as they do not need to withstand as much pressure

* Contain valves to prevent blood from flowing backward

Capillaries:

* The smallest type of blood vessel, connecting arteries to veins

* Have very thin walls, allowing for the exchange of oxygen, carbon dioxide, and other substances between the blood and the surrounding tissues

Additional types of blood vessels include:

* Arterioles: Small arteries that branch off from larger arteries

* Venules: Small veins that branch off from larger veins

* Lymph vessels: Carry lymph, a fluid that contains white blood cells and other immune cells, throughout the body