1. Veins
By: Nathan Van Belle

2. Description and System
Are tubular structures
Largest blood carrying structures along with the arteries
Have valves to prevent backflow of blood
Part of the Circulatory system

3. Function
Mostly carry deoxygenated blood except for the pulmonary veins
Always carry blood to the heart never carry blood away
Always have lower pressure than arteries
Works against gravity
Have thinner walls
More inside area
Pump to the heart by muscles surrounding vein contracting and valves opening and closing to prevent the backflow of blood

4. Impediments
Thrombosis-a clot in the blood stream that blocks the blood vessel
This can be corrected by taking one of many types of drugs some of them being blood thinners
Varicose veins-the swelling of veins because of the valves not working and the blood pooling

5. References
ogy/leg_vein_treatments.asp