A vessel of the body which usually conveys blood to body tissues. Large, medium, and small arteries (arterioles) can be distinguished. Regulation of the blood supply is determined by the activity of a smooth muscle component (under sympathetic control) which changes the diameter of the vessel cavity. With increasing age, arteries tend to become blocked with atheroma - porridge-like deposits of cholesterol-based material.
Arteries are muscular blood vessels that carry blood away from the heart.
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 gases are exchanged.
The Aorta
The aorta is the root systemic artery.
Arterioles
Arterioles, the smallest of the true arteries, help regulate blood pressure and deliver blood to capillaries.
Arterioles and blood pressure
Arterioles have the greatest collective influence on both local blood flow and on overall blood pressure. The combination of heart output (cardiac output) and total peripheral 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
Though not considered true arteries, the capillaries are where all of the important action happens in the circulatory system:
Functions of capillaries
Capillaries have no smooth muscle surrounding them and have a diameter less than that of a red blood cells;
What capillaries do:
In the lungs, carbon dioxide is exchanged for oxygen In the tissues, oxygen and carbon dioxide and nutrients and wastes are exchanged In the kidneys, wastes are released to be eliminated from the body In the intestine, nutrients are picked up, and wastes releasedBlood pressure
Systemic arterial pressures, are generated by the forceful contractions of the heart's left ventricle. (See blood pressure)
Healthy resting arterial pressures, are relatively low, mean systemic pressures typically being under 100 mmHg, about 1.8 lbf/in², above surrounding atmospheric pressure (about 760 mmHg or 14.7 lbf/in² at sea level).
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. 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.
William Harvey described and popularized the modern concept of the circulatory system and the roles of arteries and veins in the 17th century.
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