Vessels Flashcards
Lumen
Central blood-containing space
Three wall layers in arteries and veins
Tunica intima (slick surface to reduce friction)
Tunica media (muscle)
Tunica externa
Capillaries
-microscopic blood vessels
-walls of thin tunica intima
-Not found in: cartilage, epithelia, cornea, lens of eye
Tunica media is affected by
Sympathetic nervous system controlling vasoconstriction and vasodilation
Vasa vasorum
delivers nutrients to cells making up the vessels
Elastic arteries
-large thick walled arteries with elastin in all three tunics
-inactive in vasoconstriction
-aorta and its major branches
-expand and recoil as blood is ejected from the heart
Muscular arteries
-distal to elastic arteries
-active in vasoconstriction
-deliver blood to body organs
Arterioles
-smallest arteries
-lead to capillary beds
Continuous capillaries
-found in skin and muscles
-tight junctions prevent things from getting through
-blood brain barrier
Fenestrated capillaries
-has pores
-good for absorption
Sinusoid capillaries
-blood flows slowly allowing for modification
-found only in liver, bone marrow, spleen, adrenal medulla
-macrophages in lining
Capillary beds
-microcirculation: terminal arteriole -> metarteriole
Veins
aka capacitance vessels: contain up to 65 percent of blood supply
Venous valves
prevent backflow of blood
Resistance
Varies inversely with the fourth power of the vessel radius
Muscular pump
contraction of skeletal muscles that moves blood from extremities to heart
