Section of an artery
Arteries are muscular blood vessels that carry
blood away from the heart.[1] 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 nutrients 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-pressure portion of the circulatory system. Arterial
pressure varies between the peak pressure during heart contraction, called the systolic pressure, and the minimum, or 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 anatomy of arteries can be separeted into gross anatomy, at the macroscopic level,
and microscopic anatomy, which must be studied with the aid of a microscope.
Gross anatomy
- See also: Arterial tree
The arterial system to of the human body is divided into systemic
arteries, carrying blood from the heart to the whole body pulmonary arteries,
carrying blood from the heart to the lungs, and .
Systemic arteries
- See also: Systemic
circulation
- See also: Arterial tree
Systemic arteries are the arteries of the systemic circulation, which is the
portion of the cardiovascular system which carries oxygenated blood away from the heart, to the body,
and returns deoxygenated blood back to the heart.
Pulmonary arteries
- See also: Pulmonary
circulation
Pulmonary arteries are the arteries of the pulmonary circulation, which is the
portion of the cardiovascular system which carries deoxygenated blood away from the heart, to the lungs, and returns oxygenated blood back to the
heart.
Microanatomy
Anatomy of the arterial wall
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 cells. The hollow internal cavity in which the blood flows is
called the lumen.
Types of arteries
There are several types of arteries in the body:
Pulmonary arteries
The pulmonary arteries carry deoxygenated blood that has just returned from the body
to the lungs, 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 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 arterioles supply
capillaries which in turn empty into venules.
Arterioles
Arterioles, the smallest of the true arteries, help regulate blood pressure by the variable contraction of the smooth muscle of their walls, and deliver blood to the
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
arterioles, 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
tissues.
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 pressure, 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 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,[2]
and ligaments were also called "arteries".[3]
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
- ^ Medical dictionary definition of artery from KMLE Medical Dictionary retrieved on 07-04-17
- ^ Oxford English Dictionary.
- ^ 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.
See also
|
List of arteries of head and neck |
| Anterior: CC/EC |
superior
thyroid (superior laryngeal) - lingual (sublingual)
facial: cervical branches (ascending palatine, tonsillar,
submental, glandular) -
facial branches (inferior labial, superior labial, lateral nasal,
angular)
|
| Posterior and ascending: CC/EC |
occipital - posterior auricular (stylomastoid) - ascending pharyngeal
(meningeal branches) |
| Terminal, superficial temporal: CC/EC |
transverse
facial - middle temporal (zygomaticoörbital) - anterior auricular - frontal - parietal
|
| Terminal, maxillary: CC/EC |
1st part: anterior tympanic - deep auricular -
middle meningeal (superior
tympanic) - accessory meningeal - inferior alveolar (mylohyoid)
2nd part: deep temporal - pterygoid branches - masseteric -
buccal
3rd part: posterior superior alveolar - infraorbital (anterior superior
alveolar) - descending palatine - artery of the pterygoid canal - sphenopalatine |
| portions #1 and 2: CC/IC |
cervical portion (carotid sinus) -
petrous portion (Vidian, caroticotympanic) |
| cavernous portion/ophthalmic:
CC/IC |
orbital group: lacrimal (lateral palpebral) - supraorbital - posterior ethmoidal -
anterior ethmoidal - medial
palpebral - supratrochlear - dorsal
nasal
ocular group: central retinal - ciliary (short posterior, long posterior, anterior) -
superior hypophysial - inferior hypophysial
|
| cerebral portion: CC/IC |
ACA -
anterior communicating - MCA (anterolateral central) -
posterior communicating - anterior choroidal - circle of Willis |
| vertebral artery: SC |
meningeal branches - posterior
spinal - anterior spinal - PICA - basilar (pontine, labyrinthine, AICA, SCA, PCA) |
| thyrocervical trunk: SC |
inferior
thyroid (inferior laryngeal, tracheal, esophageal, ascending
cervical) - suprascapular - transverse cervical - dorsal scapular |
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
