Final answer:
Arteries are blood vessels that transport blood from the heart to the rest of the body, typically carrying oxygen-rich blood except for the pulmonary artery. They have thick walls to deal with the pressure from the heart's pumping action.
Step-by-step explanation:
The main function of the arteries is to carry blood away from the heart to various parts of the body. The largest artery is the aorta, which branches out to smaller arteries, down to arterioles, and reaches the capillaries where the exchange of nutrients and wastes occurs.
While most arteries transport oxygen-rich blood, an exception is the pulmonary artery which carries deoxygenated blood to the lungs for oxygenation. Arteries need to withstand the high pressure of blood pumped by the heart, which is why they have thick, muscular walls.