Arteries were once thought to carry air, not blood
Ancient Greek writers found empty arteries in cadavers and linked them to the windpipe—artēría once named the airway. Herophilos separated vessel types; only William Harvey in the seventeenth century made the modern circuit of arteries and veins common sense.
Today an artery is a multilayered tube that usually carries oxygenated blood from the heart to tissues in the systemic circuit. Exceptions prove the naming rule: pulmonary arteries haul deoxygenated blood to the lungs for oxygen, and fetal umbilical arteries send deoxygenated blood toward the placenta. Veins generally return deoxygenated blood, with matching pulmonary and fetal exceptions. Walls stack tunica intima, media, and externa—endothelium inside, smooth muscle and elastic tissue in the middle, collagenous adventitia outside, sometimes with vasa vasorum feeding the largest trunks. The hollow channel is the lumen.
Pressure peaks with each systole and falls in diastole, creating a palpable pulse at sites such as the wrist; arterioles act as adjustable nozzles that dominate local flow and systemic resistance via sympathetic tone. Elastic arteries larger than about ten millimeters differ from muscular ones between roughly 0.1 and 10 millimeters before feeding capillaries. Those exchange vessels are only about five micrometers wide, forcing seven-micrometer red cells to deform for gas and nutrient transfer. Mean resting systemic pressures typically stay under 100 mmHg above atmosphere; pulse pressure reflects stroke volume versus arterial elasticity.
Coronary branches leave the aorta first to feed the heart muscle itself, followed by brachiocephalic, left common carotid, and left subclavian trunks off the arch. Chronic sugar, lipoproteins, cholesterol, hypertension, stress, and smoking seed atherosclerosis—plaque of cell debris, fat, calcium, and fibrous tissue that stiffens arteries. Cut arteries can gush with the heartbeat. Historically, Empedocles imagined blood flowing to and fro without capillaries; Galen’s “vital spirits” lingered into medieval thought. William Harvey in the seventeenth century popularized the modern circuit, and Alexis Carrel later showed how to suture vessels and transplant organs.
Source: Artery
