Blood Vessels

Question 1

what is artery function

Answer 1

carry blood at high pressure away from heart
typically oxygenated apart from pulmonary artery

Question 2

what is tunica intima

Answer 2

inner layer
very smooth 1 cell thick endothelium

Question 3

what is tunica media

Answer 3

thick layer
smooth muscle - strength and can contract/relax to reduce/increase flow
elastic tissue - allow stretch to withstand pressure and recoil to even fluctuations

Question 4

what is tunica externa

Answer 4

covers outer artery
collagen prevent over stretching

Question 5

artery structure

Answer 5

1) elastic fibres - stretch withstand pressure + recoil
2) smooth muscle - control flow (vasoconstrict/dilate)
3) collagen - prevent over stretch
4) smooth endothelium - easy flow

Question 6

arterioles function

Answer 6

link artery and capillaries
lots smooth muscle to restrict blood flow
pre capillary sphincters which prevent flow into capillary bed

Question 7

capillaries function

Answer 7

link arterioles to venules and is site of exchange

Question 8

capillaries structure

Answer 8

1) very small lumen so RBC single file so slower so more exchange can occur (lowers pressure)
2) endothial pores allow substances out into tissue fluid
3) walls 1 cell thick for short distance for exchange

Question 9

venules role

Answer 9

link capillary to veins

Question 10

veins role

Answer 10

carry blood back to heart at low pressure typically deoxygenated apart from pulmonary vein

Question 11

veins structure

Answer 11

pressure low as lost through capillaries hence need for 1) valves to prevent back flow of blood
lots collagen and little elastic fibres
wide smooth lumen for easy blood flow as less friction and more blood to heart

2) big veins near large muscles in leg or arm as when they contract they squeeze veins pushing blood to heart
3) veins in chest or abdomen pumped by breathing movements