Arteries and veins are two types of blood vessels in the circulatory system.
In general, heart pumps the blood which is carried away by the arteries. These arteries branch out further as arterioles. There arterioles further branch out into capillaries to supply blood and nutrients to the deeper most part of the tissues.
These capillaries again collect waste from the cell and tissues surroundings into blood. They then converge to form venules which are bit bigger in size. These venules further converge to form veins.
These veins further form superior and inferior vena-cava which pour this impure blood into the organ heart.
Difference Between Arteries and Veins
Since arteries and veins have different role and function in circulatory system, there are also many difference in between them as seen in table below.
|Blood||They carry pure blood||They carry impure blood|
|Wall thickness||Arteries have thicker wall||The veins have thin walls|
|Body location||They are deep seated in the body.||They are peripherally loacted in the body. Hence we can see blood vessels in the back of hands, on face, legs etc.|
|Blood flow||Blood flows by pulsatile manner corresponding to heart beat.||No pulse, blood flows uniforms|
|Flow pressure||Blood flows due to pumping pressure of heart.||Blood flows due to capillary action of the veins.|
|Oxygen level||Oxygen levels is quite high in arterial blood||Oxygen level is low comparatively|
|Carbon-dioxide level||CO2 level is low in arterial blood||CO2 level is high in venous blood,|
|Flow direction||From heart to the tissues||From tissue to the heart.|
|Color||They are dark reddish color||They have bluish red color.|
|Valves||There are no valves in the artery vessels||There are valves in the veins allowing blood to flow in upward direction.|
|Diseases||Arteries are susceptible to diseases like angina pectoris, atherosclerosis||Less susceptible diseases.|
Thus arteries and veins have functional and structural differences to suit the needs of the body.
But interestingly, a pulmonary vein brings pure oxygenated blood from lungs into the heart. While a pulmonary artery carries impure blood (carbonated) from heart to the lungs. So these two are different from rest of the blood veins and arteries in function.