Blood Vessels Flashcards
Blood vessels
Arteries + veins + capillaries
Basic structure (3 layers)
Tunica externa / adventitia (superficial)
Tunica media (middle)
Tunica interna /intima (deep)
Tunica interna
endothelium (lining) = simple squamous
basement membrane = loose areolar c.t.
elastic membrane = elastic c.t
Tunica externa
Fibrous c.t (collagen + elastic fibres)
Arteries
Carry blood away from heart
Oxygenated blood
under high pressure
thick tunica media
Tunica media
Smooth muscle + elastic c.t
Elastic arteries
Thick layer of elastic tissue
tolerates big pressure changes
Distributing muscular arteries
Thick smooth muscle layer
middle size
Arterioles
Smallest
shoot muscle layer and endothelium only
Veins
Blood toward the heart
carry deoxygenated blood
under low pressure
thin tunica media
Venules
Drain blood into veins
No smooth muscle
smallest
Skeletal muscle pump
Muscle contraction massages veins (valves prevent back flow)
Respiratory pump
Changes in thoracic and abdominal pressure
Capillaries
Smallest blood vessels
form capillary beds site of exchange between blood and tissue
endothelium only
Continuous capillaries
Main exchange vessels in tissues
exchanges of nutrients, wastes, blood gasses, hormones
