- Systemic circulation
Systemic circulation is the portion of the
cardiovascular systemwhich carries oxygenated bloodaway from the heart, to the body, and returns deoxygenated blood back to the heart. The term is contrasted with pulmonary circulation. [cite book
last = Maton
first = Anthea
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
isbn = 0-13-981176-1]
In the systemic circulation,
arteriesbring 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. Veins bring deoxygenated blood back to the heart.
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.
Blood passes from arteries to
arteriolesand finally 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 tissuesdo 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.
The deoxygenated blood is then collected by
venules, from where it flows first into veins, and then into the inferior and 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.
The relatively deoxygenated 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 atriumof the heart. The coronary sinusempties the heart's veins themselves into the right atrium.
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.
Double circulatory system
Wikimedia Foundation. 2010.
Look at other dictionaries:
systemic circulation — n the passage of arterial blood from the left atrium of the heart through the left ventricle, the systemic arteries, and the capillaries to the organs and tissues that receive much of its oxygen in exchange for carbon dioxide and the return of… … Medical dictionary
systemic circulation — noun circulation that supplies blood to all the body except to the lungs • Hypernyms: ↑circulation * * * noun : the passage of arterial blood from the left auricle of the heart through the left ventricle, the systemic arteries, and the… … Useful english dictionary
systemic circulation — Anat. 1. the circulatory system in general. 2. (in mammals and birds) the circulatory system excluding the pulmonary circulation. * * * ▪ physiology in physiology, the circuit of vessels supplying oxygenated blood to and returning… … Universalium
systemic circulation — noun The part of blood circulation which carries oxygenated blood away from the heart, to the body, and returns deoxygenated blood back to the heart … Wiktionary
systemic circulation — the system of blood vessels that supplies all parts of the body except the lungs. It consists of the aorta and all its branches, carrying oxygenated blood to the tissues, and all the veins draining deoxygenated blood into the vena cava. Compare:… … The new mediacal dictionary
Круг Кровообращения Большой (Systemic Circulation) — совокупность кровеносных сосудов, которые снабжают кровью все части тела, за исключением сосудов (малого круга кровообращения) легких, в которых осуществляется газообмен. Большой круг кровообращения образован аортой и ее ветвями, по которым… … Медицинские термины
Systemic — Sys*tem ic, a. 1. Of or relating to a system; common to a system; as, the systemic circulation of the blood. [1913 Webster] 2. (Anat. & Physiol.) Of or pertaining to the general system, or the body as a whole; as, systemic death, in distinction… … The Collaborative International Dictionary of English
Systemic death — Systemic Sys*tem ic, a. 1. Of or relating to a system; common to a system; as, the systemic circulation of the blood. [1913 Webster] 2. (Anat. & Physiol.) Of or pertaining to the general system, or the body as a whole; as, systemic death, in… … The Collaborative International Dictionary of English
Systemic — may refer to:*Any body system in general, usually the nervous system. *An insecticide or fungicide whose mode of action is via uptake into a plant, entering the pest when the plant is consumed. *Systemic herbicides are translocated throughout… … Wikipedia
systemic heart — n the part of the heart propelling blood through the systemic circulation specif the left atrium and ventricle of higher vertebrates * * * left h … Medical dictionary