Blood vessels Flashcards
what is the order of blood vessels?
artery –> arteriole –> capillaries –> venule –> vein
what are the layers of blood vessels (vein and artery)?
from middle outwards,
lumen, tunica intima, tunica media, tunica externa
describe the lumen of the artery
relatively narrow
describe the tunica intima of the artery
endothelium (a very smooth layer of cells- squamous epithelium cells)
describe the tunica media of the artery
contains elastic fibres, collagen fibres and smooth muscle
describe the tunica externa
contains collagen fibres and some elastic fibres
what is the tunica externa also sometimes called?
tunica adventitia
in which direction do arteries carry blood?
Away from the heart
what blood do arteries carry?
O2 blood except pulmonary artery and umbilical artery
why is there more elastic fibres in aorta than arterioles?
because pressure has decreased
what gives arteries continuous flow?
the elastic fibres stretch (collagen limits) to take larger blood vol tf continuous flow
is the artery high or low pressure?
high
what happens when the heart relaxes, in an artery?
elastic fibres recoil - pulse
where is the only blood vessel where substances diffuse?
capilarries
describe the lumen of a vein
relatively large
describe the tunica media of a vein
very thin, contains some smooth muscle and elastic fibres
describe the tunica externa of a vein
mostly collagen fibres
in which direction does a vein pump blood?
to the heart
what blood does a vein carry?
deO2 blood apart from pulmonary vein and umbilical vein
does the vein have a pulse?
no because it has lower pressure than an artery (which does)
how many veins have valve?
most of them- medium sized
what are the function and structure of larger veins?
run between muscle which contracts to cause blood movement
what is the function of a vein during breathing?
acts as a pump to move blood back to heart
describe the lumen of a capillary
just big enough for RBC to squeeze along
