1. The Circulatory System: Blood Vessels
Human Bio 11

2. Blood Vessels
Blood flows through the body in a closed system of tubes.
Three types of blood vessels:
Arteries
Veins
Capillaries

4. Arteries
Large vessels that carry blood away from the heart to the tissues and cells.
All arteries carry oxygen-rich blood.
Except the pulmonary arteries.

6. Arteries Arteries are deep in the body. Have thick walls.
Made of connective tissue and smooth muscle.
Arterioles are small arteries.

8. Capillaries The smallest blood vessels.
Their walls are only one cell thick.
Connect arterioles and venules.
Exchange materials:
Drop off oxygen and nutrients
Absorb carbon dioxide and waste.

11. Veins Carry blood back to the heart.
All veins carry oxygen-poor blood.
Except the pulmonary veins.

13. Veins Veins are superficial (close to skin).
Have thinner walls than arteries.
Made of connective tissue and smooth muscle.
Venules are small veins.

15. Veins
Large veins have valves that close to keep blood moving back to the heart.