circulatory system Flashcards
what are the 2 components in circulatory system?
lymphatic and cardiovascular system
arteries
transport blood away from the heart and have smaller diameter
veins
return blood to the heart and have larger diameter
capillaries
thin-walled vessels where gases, nutrients, wastes, hormones, signalling sub. are exchanged
what is the function of valves?
it is in the veins to prevent blood from flowing backwards and help return to the heart
what are the 3 layers of wall in blood vessels?
tunica intima, media, and adventitia
tunica intima
- innermost lining
- basement membrane
- lamina propria (in GI, respiratory, urinary, tubes)
tunica media
- middle layer
- may have smooth muscle / elastic fibers
tunica adventitia
- outermost CT
- may contain vasa vasora = small blood vessels in the T. adventia that supply wall of large vessels
- may have longitudinal smooth muscle
function of smooth muscle in artery
for preventing backflow but not for moving blood
tunic specialization of arteries
elastic arteries: largest arteries and highest pressure
muscular arteries: medium sized
arterioles: smallest arteries
how does blood flow form arterioles to capillary bed?
via pre-capillary sphincter at the metarteriole
tunic specializations of capillaries
continuous: exchange b/w blood and surrounding tissues highly regulated -> tight junctions
fenestrated: selective exchange -> small gaps
sinusoidal: free exchange -> large gaps
tunic specialization of veins
venules: immediately ‘post capillary’, prominent tunica intima
small and medium veins: folds of tunica intima push into the lumen, prominent tunica adventitia
large veins: very prominent tunica adventiti
