Characteristics of blood vessels

Artery walls

Three layered thick wall
endothelial lining, middle smooth muscle and elastic connective tissue layer, and outer connective tissue layer

Artery actions

Carries relatively high pressure blood from the heart to the arterioles

Arteriole wall

Three layered thinner wall
Smaller arterioles have an endothelial lining, some smooth muscle tissue, and a small amount of connective tissue

Arteriole action

Helps control blood flow from arteries to capillaries by vasoconstricting or vasodilation

Capillary wall

A single layer of squamous epithelium

Capillary action

Has a membrane allowing nutrients, gases, and wastes to be exchanged between blood and tissue fluid

Venule walls

Thinner walls than arterioles with less smooth muscle and elastic connective tissue

venule action

Connects capillaries to veins

Vein wall

Thinner wall than arteries but similar layers; poorly developed middle layer; some have flap-like valves

Vein action

Carries relatively low blood pressure from venules to the heart; valves prevent blood back flow; veins serve as blood reservoirs