View source for Artery

[[Image:Anatomy_artery.png|thumb|200px|Anatomy of the arterial wall]]
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==Overview==

'''Arteries''' are [[muscular]] [[blood vessel]]s that carry [[blood]] away from the [[heart]].<ref>{{KMLEref|artery|07-04-17}}</ref> All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood.

The [[circulatory system]] is extremely important for sustaining life. Its proper functioning is responsible for the delivery of [[oxygen]] and [[nutrient]]s to all cells, as well as the removal of [[carbon dioxide]] and waste products, maintenance of optimum [[pH]], and the mobility of the elements, proteins and cells of the [[immune system]]. In developed countries, the two leading causes of [[death]], [[myocardial infarction]] and [[stroke]] each may directly result from an arterial system that has been slowly and progressively compromised by years of deterioration. (See [[atherosclerosis]]).

==Description==
The arterial system is the higher-[[blood pressure|pressure]] portion of the circulatory system. Arterial pressure varies between the peak pressure during heart contraction, called the [[systole|systolic]] pressure, and the minimum, or [[diastole|diastolic]] pressure between contractions, when the heart rests between cycles. This pressure variation within the artery produces the pulse which is observable in any artery, and reflects heart activity.

==Anatomy==

The outermost layer is known as the ''[[tunica externa]]'' formerly known as "tunica adventitia" and is composed of [[connective tissue]]. Inside this layer is the ''[[tunica media]]'', or ''media'', which is  made up of [[smooth muscle]] cells and elastic tissue.  The innermost layer, which is in direct contact with the flow of blood is the ''[[tunica intima]]'', commonly called the ''intima''. This layer is made up of mainly [[endothelial cell]]s. The hollow internal cavity in which the blood flows is called the [[lumen (anatomy)|lumen]].

==Types of arteries==
There are several types of arteries in the body:

===Pulmonary arteries===
The [[pulmonary artery|pulmonary arteries]] carry deoxygenated blood that has just returned from the body to the [[lung]]s, where [[carbon dioxide]] is exchanged for [[oxygen]].

===Systemic arteries===
Systemic arteries deliver blood to the [[arterioles]], and then to the [[capillaries]], where nutrients and gasses are exchanged.

===The Aorta===
The [[aorta]] is the root [[systemic]] artery. It receives blood directly from the left [[Ventricle (heart)|ventricle]] of the heart via the [[aortic valve]]. As the aorta branches, and these arteries branch in turn, they become successively smaller in diameter, down to the [[arteriole]]. The [[arteriole]]s supply [[capillaries]] which in turn empty into [[venule]]s.

===Arterioles===
[[Arterioles]], the smallest of the true arteries, help regulate [[blood pressure]] and deliver blood to the kidneys (capillaries).

===Arterioles and blood pressure===
[[Arterioles]] have the greatest collective influence on both local blood flow and on overall blood pressure. They are the primary "adjustable nozzles" in the blood system, across which the greatest pressure drop occurs. The combination of heart output ([[cardiac output]]) and [[systemic vascular resistance]], which refers to the collective resistance of all of the body's [[arteriole]]s, are the principal determinants of arterial blood pressure at any given moment.

===Capillaries===
The [[capillaries]] are where all of the important exchanges happen in the circulatory system. The capillaries are a single cell thick to aid fast and easy diffusion of gases, sugars and other nutrients to surrounding tissues. 

====Functions of capillaries====
To withstand and adapt to the pressures within, arteries are surrounded by varying thicknesses of [[smooth muscle]] which have extensive elastic and inelastic [[connective tissue]]s. 

The pulse pressure, i.e. [[Systolic]] vs. [[Diastolic]] difference, is determined primarily by the amount of blood ejected by each heart beat, [[stroke volume]], versus the volume and elasticity of the major arteries.

Over time, elevated arterial [[blood sugar]] (see [[Diabetes Mellitus]]), [[lipoprotein]] [[cholesterol]], and [[high blood pressure|pressure]], [[Tobacco smoking|smoking]], and other factors are all involved in damaging both the [[endothelium]] and walls of the arteries, resulting in [[atherosclerosis]] or [[Diabetes Mellitus]].

==History==
Among the ancient Greeks, the arteries were considered to be "air holders"  that were responsible for the transport of air to the tissues and were connected to the [[vertebrate trachea|trachea]]. This theory presumably arose from the fact that the arteries are empty after death: the last beat of the heart pushes the blood through the capillaries and into the veins.

In medieval times, it was recognized that arteries carried a fluid, called "spiritual blood" or "vital spirits", considered to be different from the contents of the veins. This theory went back to [[Galen]].  In the late medieval period, the [[trachea]],<ref>Oxford English Dictionary.</ref> and [[ligaments]] were also called "arteries".<ref>Shakespeare, William. Hamlet Complete, Authoritative Text with Biographical and Historical Contexts, Critical History, and Essays from Five Contemporary Critical Perspectives. Boston: Bedford Books of St. Martins Press, 1994. pg. 50.</ref>

[[William Harvey]] described and popularized the modern concept of the circulatory system and the roles of arteries and veins in the 17th century.

[[Alexis Carrel]] at the beginning of 20th century first described the technique for vascular suturing and anastomosis and successfully performed many organ transplantations in animals; he thus actually opened the way to modern vascular surgery that was before limited to vessels permanent ligatation.

==References==
{{Reflist}}

==See also==
* [[Peripheral arteries]]
* [[Arterial tree]]
* [[Blood]]

{{cardiovascular system}}
{{Arteries of head and neck}}   
{{Arteries of upper limbs}} 
{{Arteries of chest}}
{{Arteries of abdomen}}
{{Arteries of lower limbs}} 


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[[CME Category::Cardiology]]

[[Category:Cardiovascular system]]
[[Category:Angiology]]
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