Blood vessels- transport in animals Flashcards
1
Q
elastic fibres
A
composed of elastin, can stretch and recoil providing vessel walls with flexibility
2
Q
smooth muscle
A
contracts or relaxes which changes the size of lumen
3
Q
collagen
A
provides structural support to maintain the shape and volume of vessel
4
Q
arteries
A
- carry oxygenated blood (except pulmenory artery) away from heart
- walls contain elastic fibres, smooth muscle and collagen
5
Q
arterioles
A
- link arteries and capilleries
- more smooth muscle, less elastin in walls, can constrict or dilate to control flow of blood into individual organs
6
Q
vasoconstriction + vasodilation
A
- when smooth muscle in arterioles contracts it constricts the vessel and prevents blood flowing into a capillary bed
- when smooth muscle in arteriole relaxes, blood flows through into the capillary bed
7
Q
capillaries
A
- microscopic blood vessels that link arterioles with the venules
- extremely small lumen
- substances exchanged through capillary walls
8
Q
adaptions of capillaries
A
- large SA for diffusion
- total cross section greater than arteriole supplying them so rate of blood flow falls=more time for exchange of materials
- walls are a single endothelial cell thick = rapid diffusion
9
Q
veins
A
-carry deoxygenated blood (except pulmenory vein)
away from cells of body towards heart
-deoxygenated blood flows from capillaries into v small veins called venules and then into larger veins
then to vena cava (inferior and superior)
10
Q
adaption of veins
A
- no pulse
- hold 60%of blood volume
- pressure v low
- contain valves
- walls contain lots of collagen and little elastic fibre
- wide lumen and a smooth thin lining (endothelium ) so blood flows easily
- many larger veins run between big active muscles which squeeze veins forcing blood to move upwards
11
Q
venules
A
- link capillaries with veins
- many venules make up a vein
