Arteries and veins are a vital part of the circulatory system of all vertebrates. Click on this link for more information about the human circulatory system.
Arteries and veins work together to transport blood throughout the body, working to remove waste from cells as well as preoxygenating them in the process. Arteries transport oxygenated blood away from the heart, while veins take deoxygenated blood (oxygen-depleted) back to the heart. The only exceptions to this set up are the pulmonary vessels. In this case, pulmonary veins take oxygenated blood from the lungs to the heart, while pulmonary arteries transport deoxygenated blood from the heart back to the lungs.
While this may be one of the major differences between artery and vein, there are distinctions that are worthy of note:
– They are found deeper within the body.
– They are made of very thick muscular walls because they have to deal with pressure coming from the heart.
– They do not have valves.
– They have a narrow lumen and rigid walls
– Muscles of the arterial wall contract.
When it comes to veins, these characteristics are a reverse :
– They are found beneath the skin
– Their walls are thin and not elastic because their transport route ensures that they are not subjected to pressure.
– Veins are made up of valves.
– Veins equally have a wider lumen than what can be found in arteries.
– Inside of rigid walls, veins have walls that are collapsible.
– Pulses cannot be detected in the veins.
– Muscles of the arterial wall do not contract.
Since arteries carry oxygenated blood most of the time, they are usually bright red in color when bright light is shone on them. Veins, however, take up a darker color because of the low oxygen contained in the blood that they carry.