AP2 Ch21 Blood Vessels

tunica interna

innermost layer of blood vessel

• includes endothelial lining, a layer of connective tissue with elastic fibers

• arteries also have outer margin called internal elastic membrane

tunica media

middle layer of blood vessel; contains concentric sheets of smooth muscle

• normally the thickest layer in a small artery

• separated from tunica externa by a thin layer of elastic fibers called the external elastic membrane

• when smooth muscle contracts, the vessel diameter decreases

tunica externa (adventitia)

outermost layer of blood vessel; connective tissue

• normally thicker than tunica media in veins

arteries

Do arteries or veins have thicker walls and are better at maintaining shape?

valves

Veins contain _____, which prevent backflow of blood toward capillaries.

vasoconstriction

when smooth muscle in an artery contracts; reduces the movement/flow of blood; reduces blood loss at injury site

vasodilation

when smooth muscle in an artery relaxes; increases the diameter of vessel and increases blood flow

arteries

carry oxyenated blood away from heart

arterioles

smaller branched arteries

capillaries

smallest vessels; where diffusion occurs between blood and interstitial fluids

venules

smaller “veins” that unite to form actual veins

veins

vessels that return deoxygenated blood to the heart

pulse

types: radial, carotid; normal: 60-90 bpm

blood pressure (BP)

refers to arterial pressure; range: 90-140 mmHg

• type: brachial; normal: 120/80 mmHg

capillary hydrostatic pressure (CHP)

pressure in capillary bed 18-35 mmHg

venous pressure

pressure in venous systems 18 mmHg

vascular resistance

largest type of resistance; this is friction between blood and vessel wall

viscosity

resistance to flow by components in a liquid; thicker liquids travel slower and blood has lots of proteins to cause it to be viscous

turbulence

caused by high blood flows, irregular surfaces and changes in vessel diameter; this causes eddies and swirls