Artery Categories and Functions

Veins

Carry deoxygenated blood back to the heart

Arteries

Carry oxygenated blood away from the heart

Blood pressure

Force exerted by blood against the walls of blood vessels

Tunica intima

Innermost layer of both arteries and veins

Distributing arteries

Intermediate-sized arteries, muscular, distribute blood to specific organs

Conducting arteries

Largest arteries, elastic, e.g., aorta

Tunica media

Middle layer of both arteries and veins, contains smooth muscle

Vasoconstriction

Narrowing of blood vessels, increases peripheral resistance

Resistance

Opposition to blood flow in blood vessels

Tunica externa

Outer layer of both arteries and veins, supporting connective tissue

Vein valves

Prevent backflow of blood in veins

Large veins

Result from convergence of medium-sized veins, e.g., vena cavae

Medium-sized veins

Result from convergence of venules, have one-way valves

Pulse

Rhythmic expansion and contraction of arteries

Arterioles

Smallest arteries, control blood flow into capillaries

Capillary

Smallest blood vessel, site of exchange between blood and tissues

Capillaries

Smallest blood vessels for exchange between blood and tissues

Venules

Smallest veins, collect blood from capillaries

Blood volume

Total amount of blood in the circulatory system

Vasodilation

Widening of blood vessels, decreases peripheral resistance