Blood vessels space an integral ingredient of the circulatory system. The five species of blood vessels room (in order of circulation): arteries, arterioles, capillaries, venules, and veins. The primary function of big blood ship (i.e., arteries and veins) is the transport of blood to and also from the heart, whereas smaller sized blood vessels (e.g., capillaries) permit substance exchange in between the cells and also blood. Arteries bring oxygen-rich blood native the love to the periphery. Once they with an body organ or limb, lock branch and divide into arterioles and also eventually right into numerous tiny capillaries, developing a capillary bed that allows the distribution of oxygen and also nutrients come the bordering tissues. Distal come the capillary bed, postcapillary venules sign up with together to kind veins, which provide oxygen-poor blood ago to the heart. Both arteries and also veins space composed that the exact same three layers of tissue: the tunica intima, tunica media, and also tunica adventitia. Arteries save on computer significantly much more smooth muscle than veins (especially in the tunica media) whereas veins save valves in the tunica intima. Capillaries are entirely composed of one endothelial layer through or there is no a basement membrane. There room three different varieties of capillaries (continuous, fenestrated, and also sinusoidal), every one of which differ in terms of permeability and also function. Blood vessels are referred to collectively as the vascular device and, together with the heart, consist of the circulatory device or cardiovascular system.

A separate article on vascular physiology addresses the topics of hemodynamics, blood press regulation, and also capillary exchange.


Large blood vessels

Consist that arteries and also veins, which have actually the three main microscopic wall layers.

Large blood vessel great


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Layer (from the lumen outward)

Sublayers Components role Tunica intima (intima) Tunica media (media) Tunica adventitia (externa/adventitia)
Selective permeability Regulation of: Coagulation Vessel width Angiogenesis (via VEGF)
Subendothelial layer
internal elastic lamina
Muscular class
outside elastic lamina ship elasticity
No sublayers Attaches ship to neighboring structures



Function: transportation of arterial (oxygenated) blood from the heart to the perimeter Exceptions: Pulmonary artery types of arteries: blood vessel wall surface components vary according to the ar and function
Elastic arteries Muscular arteries Location Components the the tunica media Function
Vessels close to the heart (aorta , pulmonary trunk, and their big branches) Vessels farther indigenous the love (e.g., brachial artery, femoral artery)

Primarily elastic yarn

Primarily smooth muscle

Absorb energy of left ventricular convulsion of the heart throughout systole → dampen pulsatile blood flow to alleviate the difference in blood pressure between systole and diastole

Regulate blood flow through the lumen by changing vascular resistance (i.e., resistance vessels)



Function: transportation of venous (deoxygenated) blood indigenous the periphery to the love Exceptions:


Differences in between arteries and also veins

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Characteristics Arteries Veins Blood push Diameter of the lumen Features of the class Intima Media Adventitia
High Low
Relatively small Relatively large
No valves creates valves to stop retrograde blood flow
The thickest class
Relatively thin Thick compared to various other layers