Final answer:
Veins are blood vessels that carry blood toward the heart and most veins carry deoxygenated blood. Blood moves through veins by the squeezing action of surrounding skeletal muscles, and valves in veins prevent the backflow of blood.
Step-by-step explanation:
Veins are blood vessels that carry blood toward the heart. They are thin-walled vessels with large and irregular lumens. Most veins carry deoxygenated blood. Blood moves through veins by the squeezing action of surrounding skeletal muscles, and valves in veins prevent the backflow of blood.