Write 3-4 paragraphs comparing and contrasting arteries and veins. what are they? what is their purpose? how do they function? include an explanation of a common medical issues for both.

Arteries and veins are blood vessels. They are essential parts of the circulatory system. Although both of them are considered as blood vessels, they have different purposes and have a slight difference in their structure. The main purpose of these blood vessels are to carry blood throughout the body and distribute the nutrients and oxygen from the blood and at the same time, help with eliminating waste.  

The role of arteries is to carry blood from the heart to carry blood away from the heart. Almost all the arteries in the body carry, what we call oxygenated blood. This is blood that has been oxygenated or received oxygen from the lungs. Only the pulmonary artery carries unoxygenated blood. Arteries are a thicker structurally than veins. This is because they need to be able to withstand the pressure that comes from the pumping of the heart. 

The role of veins on the other hand is to carry blood to the heart. Almost all veins in the body carry unoxygenated blood. The only vein in the body that carries oxygenated blood is the pulmonary vein. Now veins have thinner walls than arteries. 

A common medical issue for both would be hypertension. This occurs when the pressure exerted by blood on the blood vessels is too high. Without treatment this condition can cause other cardiovascular problems. Although this is generally a blood vessel issue, hypertension affects arteries the most because more pressure is exerted on the arteries than veins. 

Varicose veins is another common issue which occurs in the leg veins. They are more common in women than men. This happens when the valves in the veins fail, which causes backflow of blood. The back flow causes increases pressure on the veins and causes dilation.