Systemic circulation
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2008-05-30T14:21:03Z
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/* Capillaries */
[[Image:Illu systemic circuit.svg|thumb|300px]]
'''Systemic circulation''' is the portion of the [[cardiovascular system]] which carries [[oxygen]]ated [[blood]] away from the heart, to the [[body]], and returns deoxygenated blood back to the heart. The term is contrasted with [[pulmonary circulation]].<ref>{{cite book
| last = Maton
| first = Anthea
| authorlink =
| coauthors = Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright
| title = Human Biology and Health
| publisher = Prentice Hall
| date = 1993
| location = Englewood Cliffs, New Jersey
| pages =
| url =
| doi =
| id =
| isbn = 0-13-981176-1}}</ref>
==Course==
In the systemic circulation, [[arteries]] bring oxygenated blood to the tissues. As blood circulates through the body, oxygen diffuses from the blood into cells surrounding the capillaries, and carbon dioxide diffuses into the blood from the capillary cells. [[Vein]]s bring deoxygenated blood back to the heart.
===Arteries===
{{Seealso|Arterial tree}}
Oxygenated blood enters the systemic circulation when leaving the [[left ventricle]], through the aortic [[semi-lunar valve]]. The first part of the systemic circulation is the artery [[aorta]], a massive and thick-walled artery. The aorta arches and gives off major arteries to the upper body before piercing the diaphragm in order to supply the lower parts of the body with its various branches.
====Capillaries====
Blood passes from [[Artery|arteries]] to [[capillaries]], which are the thinnest and most numerous of the blood vessels. These capillaries help to join tissue with arterioles for transportation of nutrition to the cells, which absorb oxygen and nutrients in the blood. [[Peripheral tissues]] do not fully deoxygenate the blood, so venous blood does have oxygen, but in a lower concentration than in arterial blood. In addition, carbon dioxide and wastes are added.
===Venules===
The deoxygenated blood is then collected by [[venule]]s, from where it flows first into [[vein]]s, and then into the [[inferior vena cava|inferior]] and [[superior vena cava|superior]] [[venae cavae]], which return it to the [[right heart]], completing the systemic cycle. The blood is then re-oxygenated through the pulmonary circulation before returning again to the systemic circulation.
===Veins===
The relatively de-oxygenated blood collects in the venous system which coalesces into two major veins: the [[superior vena cava]] (roughly speaking from areas above the heart) and the [[inferior vena cava]] (roughly speaking from areas below the heart). These two great vessels exit the systemic circulation by emptying into the [[right atrium]] of the [[heart]]. The [[coronary sinus]] empties the heart's veins themselves into the right atrium.
==Advantage==
Because the systemic circulation is powered by the left ventricle (which is very muscular), one advantage of this form of circulation - as opposed to [[open circulation]], or the gill system that fish use to breathe - is that there is simultaneous high-pressure oxygenated blood delivered to all parts of the body.
==References==
<references/>
==See also==
*[[Pulmonary circulation]]
*[[Double circulatory system]]
{{cardiovascular system}}
{{Arteries of head and neck}}
{{Arteries of upper limbs}}
{{Arteries of chest}}
{{Arteries of abdomen}}
{{Arteries of lower limbs}}
[[Category:Cardiovascular system]]
[[ar:دوران مجموعي]]
[[la:Circulatio systemica]]
[[sl:Sistemski krvni obtok]]