Structure of blood vessels

lumen (inside space); 1-3 layers in wall

Tunica externa

areolar connective tissue w/ elastic fibers

tunica media

circular layers of smooth muscle tissue

tunica intima (interna)

simple squamous layer w/ think areolar layer

Types of blood vessels

arteries; capillaries; veins

Arteries

carry blood away from heart; usually oxygenated blood (except pulmonary arteries)

elastic arteries

largest arteries and have elastic tissues throughout but especially around t. media

muscular arteries

medium size arteries and have a larger smooth muscle layer; carry blood to the organs and tissues

smallest arteries

arterioles

Capillaries

smalles blood vessels; t. intima only; one squamous cell thick; nutrients/wastes exchanged b/t blood and tissue fluid; 40 billion capillaries arranged in beds; flow controlled by precapillary sphincter muscles

Continuous capillaries

most common, form continous lining connected by tight junctions

fenestrated capillaries

have holes in them are located where fluid is transported b/t blood and interstitial tissues

sinusoidal capillaries

wide and larger vessels allowing transport of larger materials such as proteins or cells (bone marrow, anterior pituitary gland, spleen, liver)

Veins

carries blood towards heart; usually deoxgenated blood; vein walls are relatively think; veins hold 60% of body's blood supply at rest; all three tunicas; very low blood pressure

Pulmonary circulation

right side to lungs and back

systemic circulation

left side to body and back