what do blood vessels do?
- help w movement of blood form heart to periphery and back
- resist pressure from heart
- prevent backflow when pressure drops
- provide transport to and from tissue, then to and from lumen of vessel
- regulate & respond to changes in pressure
what are the major differences between arteries, veins, and capillaries?
- arteries = thick walls, smaller lumen
- veins = thinner walls, bigger lumen, valves
- capillaries = thinnest walls for gas exchange
describe the 3 layers of blood vessels
1) tunica intima (inner) = lining endothelium continuous with endothelium of heart, subendothelial CT, internal elastic lamina
2) tunica media (middle) = smooth muscle
3) tunica adventitia (outer) = dense/elastic CT; support
what are the 2 types of autoregulation?
1) myogenic = intrinsic contractile response of smooth muscle when stretched
2) metabolic
how can you tell the difference between an artery and a vein?
- arteries have thicker tunica media, thinner adventitia
- veins have thinner tunica media, and thicker adventitia, contains valves
how are new blood vessels formed?
- vasculogenesis = during development
- angiogenesis = response to injury or cancer
why does the aorta not have any valves?
high pressure vessel
what is another name for aorta and the vena cava?
elastic artery/vein = substantial elastic fibers in tunica media
what is present in the medium artery that is lost in the medium vein?
internal elastic lamina
what are the features of small artery/vein and arteriole/venule?
- NO or minimal elastic lamina for small vessels
- NO elastic lamina for arteriole/venule
what are the tunica media layers of small vessels?
- small artery = 2-4
- small vein = 1-2
- arteriole = 1-2
- venule = 0
what are the 3 types of capillaries?
- continuous = tight junctions
- fenestrated = more movement across cell
- discontinuous = aka sinusoid; found in liver and spleen
what moves things across capillaries that cannot fit through fenestrations?
pinocytotic vesicles
name something that differentiates lymph vessels from blood vessels
no RBCs in lymph vessel lumen
what do lymph vessels and veins have in common?
valves
what is vasa vasorum?
- small blood vessels found in the tunica adventitia of large arteries/veins
- provides nutrients and remove waste from outermost layers of vessels with the thickest walls
- *any blood vessel in tunica adventitia is part of vasa vasorum
what are characteristics of discontinuous capillaries?
- incomplete basement membrane
- bigger pores / fenestrations
- bigger intercellular cleft
