The Artery
by Tessa Gedatus
The artery is designed to move oxygenated blood away from the heart. The largest artery is the aorta, which other, smaller, arteries branch off of. This pattern of diminishing branches continues down to the smallest arteries, arterioles, which supply capillaries with oxygenated blood for surrounding tissues.
There are three distinct tissue layers that make up any artery. The innermost layer, the endothelium or tunica intima, is fine layers of elastic fibers and connective tissue. This is surrounded by a thick smooth muscle layered with elastic fibers. This layer, the tunica media, is involuntary muscle. It is responsible for contractions that move the blood, and are what you feel when you take a pulse. Finally, the outermost layer, the tunica adventitia, is tough connective tissue made mostly of collagen.
The relatively thick middle layer and the flexible but strong outer layer that make up an artery allow it to hold its rounded shape, withstand the force of blood pressure without tearing, and also expand to alleviate moderate pressure changes.
"artery: transverse section of an artery". Illustration. Encyclopædia Britannica Online. Web. 02 Feb. 2017.
<https://www.britannica.com/science/artery?oasmId=121565>
image source: http://archimede.bibl.ulaval.ca/archimede/fichiers/23201/ch01.html
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