An elastic artery (conducting artery or conduit artery) is an
artery
An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...
with many
collagen
Collagen () is the main structural protein in the extracellular matrix of the connective tissues of many animals. It is the most abundant protein in mammals, making up 25% to 35% of protein content. Amino acids are bound together to form a trip ...
and
elastin
Elastin is a protein encoded by the ''ELN'' gene in humans and several other animals. Elastin is a key component in the extracellular matrix of gnathostomes (jawed vertebrates). It is highly Elasticity (physics), elastic and present in connective ...
filaments in the
tunica media
The tunica media (Neo-Latin "middle coat"), or media for short, is the middle tunica (layer) of an artery or vein. It lies between the internal elastic lamina of the tunica intima on the inside and the tunica externa on the outside.
Artery
The ...
, which gives it the ability to stretch in response to each pulse. This elasticity also gives rise to the
Windkessel effect, which helps to maintain a relatively constant pressure in the arteries despite the pulsating nature of the blood flow.
Elastic arteries include the largest arteries in the body, those closest to the heart. They give rise to medium-sized vessels known as
distributing arteries (or ''muscular arteries'').
The
pulmonary arteries
A pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The largest pulmonary artery is the ''main pulmonary artery'' or ''pulmonary trunk'' from the heart, and ...
, the
aorta
The aorta ( ; : aortas or aortae) is the main and largest artery in the human body, originating from the Ventricle (heart), left ventricle of the heart, branching upwards immediately after, and extending down to the abdomen, where it splits at ...
, and its branches together comprise the body's system of elastic arteries. Other examples include the
brachiocephalic artery
The brachiocephalic artery, brachiocephalic trunk, or innominate artery is an artery of the mediastinum that supplies blood to the right arm, head, and neck.
It is the first branch of the aortic arch. Soon after it emerges, the brachiocephalic ...
,
common carotid arteries,
subclavian artery
In human anatomy, the subclavian arteries are paired major arteries of the upper thorax, below the clavicle. They receive blood from the aortic arch. The left subclavian artery supplies blood to the left arm and the right subclavian artery suppli ...
, and
common iliac artery
The common iliac artery is a large artery of the abdomen paired on each side. It originates from the aortic bifurcation at the level of the 4th lumbar vertebra. It ends in front of the sacroiliac joint, one on either side, and each bifurcates ...
.
Structure
The most prominent feature of elastic arteries is the very thick
tunica media
The tunica media (Neo-Latin "middle coat"), or media for short, is the middle tunica (layer) of an artery or vein. It lies between the internal elastic lamina of the tunica intima on the inside and the tunica externa on the outside.
Artery
The ...
in which elastic lamellae alternate with layers of
smooth muscle
Smooth muscle is one of the three major types of vertebrate muscle tissue, the others being skeletal and cardiac muscle. It can also be found in invertebrates and is controlled by the autonomic nervous system. It is non- striated, so-called bec ...
fibers. The adult aorta has about 50 elastic lamellae.
The
tunica intima
The tunica intima (Neo-Latin "inner coat"), or intima for short, is the innermost tunica (biology), tunica (layer) of an artery or vein. It is made up of one layer of endothelium, endothelial cells (and macrophages in areas of disturbed blood flo ...
is well developed, with many smooth muscle cells in the subendothelial
connective tissue
Connective tissue is one of the four primary types of animal tissue, a group of cells that are similar in structure, along with epithelial tissue, muscle tissue, and nervous tissue. It develops mostly from the mesenchyme, derived from the mesod ...
, and often shows folds in cross section because of the vessel’s contraction with loss of
blood pressure
Blood pressure (BP) is the pressure of Circulatory system, circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term ...
at death. Between the intima and the media lies the
internal elastic lamina
The internal elastic lamina or internal elastic lamella is a layer of elastic tissue that forms the outermost part of the tunica intima of blood vessels. It separates tunica intima from tunica media.
Histology
It is readily visualized with light ...
, usually better defined than the elastic laminae of the media. The relatively thin adventitia contains
vasa vasorum
Vasa vasorum are networks of small blood vessels that supply the walls of large blood vessels, such as elastic arteries (e.g., the aorta) and large veins (e.g., the venae cavae).
The name derives . Occasionally, two different singular forms ar ...
, which also supply elastic arteries,
unlike smaller blood vessels, which are supplied by
diffusion
Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical p ...
.
Physiology
The numerous elastic laminae of these arteries contribute to their important function of making
blood flow
Hemodynamics American and British English spelling differences#ae and oe, or haemodynamics are the Fluid dynamics, dynamics of blood flow. The circulatory system is controlled by homeostasis, homeostatic mechanisms of autoregulation, just as hydrau ...
more uniform. During ventricular contraction (
systole
Systole ( ) is the part of the cardiac cycle during which some chambers of the heart contract after refilling with blood. Its contrasting phase is diastole, the relaxed phase of the cardiac cycle when the chambers of the heart are refilling ...
), blood moves through the arteries forcefully, stretching the
elastin
Elastin is a protein encoded by the ''ELN'' gene in humans and several other animals. Elastin is a key component in the extracellular matrix of gnathostomes (jawed vertebrates). It is highly Elasticity (physics), elastic and present in connective ...
and distending the wall within limits set by its content of
collagen
Collagen () is the main structural protein in the extracellular matrix of the connective tissues of many animals. It is the most abundant protein in mammals, making up 25% to 35% of protein content. Amino acids are bound together to form a trip ...
. When the ventricles relax (
diastole
Diastole ( ) is the relaxed phase of the cardiac cycle when the chambers of the heart are refilling with blood. The contrasting phase is systole when the heart chambers are contracting. Atrial diastole is the relaxing of the atria, and ventricul ...
), ventricular pressure drops to a low level, and the elastin layers rebound passively, helping to maintain
arterial pressure. The aortic and pulmonary valves prevent backflow of blood into the heart, so blood continues to flow away from the heart during this rebound. Arterial blood pressure and blood velocity decrease and become less variable as the distance from the heart increases.
References
External links
*
Histology at usc.edu
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Arteries