Editing Circulatory system (section)

====Arteries====
{{main|Artery}}
{{See also|Arterial tree}}
[[File:Vein_art_near.png|thumb|Depiction of the heart, major veins and arteries constructed from body scans]]
Oxygenated blood enters the systemic circulation when leaving the left ventricle, via the [[Aortic valve|aortic semilunar valve]].<ref name="Iaizzo">{{cite book|url=https://books.google.com/books?id=4PLuCgAAQBAJ|title=Handbook of Cardiac Anatomy, Physiology, and Devices|publisher=Springer|author=Iaizzo, Paul A|year=2015|page=93|isbn=978-3-31919464-6|access-date=2022-01-28|archive-date=2017-10-11|archive-url=https://web.archive.org/web/20171011044440/https://books.google.com/books?id=4PLuCgAAQBAJ|url-status=live}}</ref> The first part of the systemic circulation is the aorta, a massive and thick-walled artery. The aorta arches and gives branches supplying the upper part of the body after passing through the aortic opening of the diaphragm at the level of thoracic ten vertebra, it enters the abdomen.<ref name="Iaizzo two">{{cite book|url=https://books.google.com/books?id=4PLuCgAAQBAJ|title=Handbook of Cardiac Anatomy, Physiology, and Devices|publisher=Springer|author=Iaizzo, Paul A|year=2015|pages=5, 77|isbn=978-3-31919464-6|access-date=2022-01-28|archive-date=2017-10-11|archive-url=https://web.archive.org/web/20171011044440/https://books.google.com/books?id=4PLuCgAAQBAJ|url-status=live}}</ref> Later, it descends down and supplies branches to abdomen, pelvis, perineum and the lower limbs.<ref name="Iaizzo three">{{cite book|url=https://books.google.com/books?id=4PLuCgAAQBAJ|title=Handbook of Cardiac Anatomy, Physiology, and Devices|publisher=Springer|author=Iaizzo, Paul A|year=2015|pages=5, 41–43|isbn=978-3-31919464-6|access-date=2022-01-28|archive-date=2017-10-11|archive-url=https://web.archive.org/web/20171011044440/https://books.google.com/books?id=4PLuCgAAQBAJ|url-status=live}}</ref>

The walls of the aorta are elastic. This elasticity helps to maintain the [[blood pressure]] throughout the body.<ref name="Vaz">{{cite book|url=https://books.google.com/books?id=J_HQDwAAQBAJ&pg=PA255|title=Guyton & Hall Textbook of Medical Physiology – E-Book: A South Asian Edition|publisher=Elsevier Health Sciences|author1=Vaz, Mario|author2=Raj, Toni|author3=Anura, Kurpad|year=2016|page=255|isbn=978-8-13-124665-8|access-date=2022-01-28|archive-date=2022-01-28|archive-url=https://web.archive.org/web/20220128215455/https://books.google.com/books?id=J_HQDwAAQBAJ&pg=PA255|url-status=live}}</ref> When the aorta receives almost five litres of blood from the heart, it recoils and is responsible for pulsating blood pressure. As the aorta branches into smaller arteries, their elasticity goes on decreasing and their compliance goes on increasing.<ref name="Vaz"/>