2. Tunica interna (intima) Inner layer of arteries and veins Endothelium made of simple squamous epithelial cells

3. Tunica media Consists of smooth muscle

4. Tunica externa (adventitia) Made of connective tissue

5. Artery

6. Arteriole Small blood vessel coming off a larger artery

7. Capillary Filled with red blood cells Smallest of the body’s blood vessels

8. Venule Small blood vessel feeding into a larger vein

9. Arteriole and Venule Compared Arteriole Venule

10. Vein

11. One-way valve

12. Oxygenated blood (red vessels)

13. Deoxygenated blood (blue vessels)