Artery refers to the continuous branching from the heart into small arteries, which end in the tissueblood vesselIt transports blood from the heart to all parts of the body. Due to the high internal pressure,Blood flow velocityFaster.Arterial wallThicker,Elastic fibreMore, the lumen section is round, with contractility and elasticity, which can pulse obviously with the heart contraction and blood pressure.The function of arterial wall is to expand the wall when the ventricle ejects blood;Ventricular diastoleThe tube wall retracts and the blood continues to flow forward.
Blood is introduced into capillaries by various arteries.So the artery is between the ventricle andblood capillaryThe pipe between the two chambers is close to the ventricle, with large diameter and thick wall.After repeated branching, the pipe diameter gradually becomes smaller, the pipe wall becomes thinner, and finally forms capillaries with similar structure to capillariesarteriole, connected with capillaries.Although the diameter and wall thickness of arteries differ greatly, they have something in common in structure.It is generally composed of three layers of membrane, and the innermost layer is called tunicaintima）, byendotheliumAnd verticalconnective tissueComposition;The middle layer is calledMesomembrane(tu nica media), consisting of ring-shaped tissues;The outermost floor is calledadventitia(tunicaadventitia）, which is composed of connective tissue arranged vertically.connectArterial trunkSingle transverse balance betweenTraffic branch(communicating branch)；Two or more collateral branches from the vascular trunk anastomose with each othercollateral anastomoses (collateral anastomoses)；The branches of different arteries anastomose each other in a network on a plane called vascular net;Vascular network exists at joints, called articular network（articularnet)；Vascular branches of easily compressed parts of the body or highly active organs can anastomose with each other to formArterial arch(arcus ar-teriosus)。There are structural atypical arteries in the human body, such as cerebral arteries andDura materArteries, because they are protected by the skull, have very thin tube walls and well-developed internal elastic membranes, while the middle and outer membranes are poorly developed;in additionpulmonary arteryBecause the pressure is far more thanaortaIs small,smooth muscleAnd elastic membrane are less, so although the pipe diameter is large, the pipe wall is relatively weak.umbilical arteryThere is no internal elastic membrane, while the smooth muscle of the middle membrane is divided into internal longitudinalOuter ringTwo layers, the adventitia is not obvious, which is also an atypical artery.Age change of arterial wall, fromEmbryonic stageAfter birth, the middle membrane of blood vessels is the most obvious.The elastic membrane increases from 20 to 25 years old, and reaches 50 to 60 layers in adults.The arterial wall is oftenNervousnessIt not only bears a high blood pressure, but also is constantly impacted by blood flow, which is prone to damage.With the increase of age, the arterial wall may be sclerotic to varying degrees, especiallycoronary arteryThe cerebral artery wall is prone to atherosclerosis, which makes the artery lumen narrow.
Anatomical structure of arteries
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Arteries carry blood from the heart to all parts of the body.In this process, the blood flows through the artery with decreasing diameter.The arterial wall has three layers of tunica adventitia, tunica media and tunica intima.The difference between different types of arteries lies in their thickness and composition of the capsule.
cardiovascular system
The heart and blood vessels carry blood throughout the body, and most arteries willOxygen enrichmentOur blood is transported out of the heart;Most veins carry hypoxic blood back to the heart.However, it originated fromTruncus pulmonisThe pulmonary artery of,pulmonary veinTransports oxygen rich blood from the lungs back to the heart.
Structure of blood vessels
Vascular wallIt is composed of three concentric circular membranes.Venous wallIt has less muscle, so it is thinner than the accompanying artery wall. The lumen of the vein is larger, and it looks very smooth on the tissue slice. Most of the middle veins can overcome gravity to transport blood back to the heart, which is due toVenous valve, which can prevent blood reflux.Physiological conditionsIt can ensure that the blood flow is different only in the direction of the heart, especially in the middle membrane.The size of arteries changes continuously, that is, from one type of artery to anothermorphological characterIs gradually changing（GartnerAnd Hiatt, 1977).Arteries can be divided into three types:
(1) Elastic artery (delivery artery): the thickest one.The aorta and its branches are typical elastic arteries.The elasticity of these blood vessels can maintain a constant blood pressure during the contraction (relaxation) period of the heart.When the heart contracts, the elastic artery expands, and the elastic artery returns to its original position during the contraction interval;
(2) Muscular artery (distributing artery): distributing blood to different parts of the body, such asFemoral artery。Their walls are mainly composed of circular smooth muscles.Smooth muscle contraction can shrink the lumen, making the internal space of the artery smaller.The muscular artery can be adjusted to different parts of the body according to the needs of the human bodyblood flow；
(3) Arterioles: the smallest one.Their lumens are narrow and their wallsMuscularisRelatively thick.Vascular systemThe arterial pressure in the middle is mainly regulated by the tension of the smooth muscle in the wall of the arterioles.If the tension is higher than normalhypertension。
