There are three main types of blood vessels in our bodies.

• Arteries carry blood away from the heart to the tissues and organs in the body.
  • The blood in arteries is carrying oxygen.
• Veins carry blood from the tissues and organs in the body to the heart.
  • The blood in veins is carrying carbon dioxide.

• Capillaries are very tiny blood vessels that connect arteries to veins.
  • The blood in capillaries exchanges oxygen, carbon dioxide, food, and waste with body tissues and cells.
  • In the capillaries oxygen and food move from blood to the cells.
  • In the capillaries carbon dioxide and waste move from the cells to the blood.

This transportation system not only keeps materials moving to and from cells in the body. It also spreads heat so that the body stays at a constant^* temperature.