blood circulation Flashcards
blood direction of arteries
carry blood away from heart to the cells of the body
-all carry oxygenated blood
pulmonary artery
carries deox blood from heart to lung
umbilical artery
during pregnancy, carries deox blood from fetus to placenta
features of the lumen
-central space inside the blood vessel
-gets smaller further away it is from heart
arterioles
smallest branches of arterial system
-furthest from heart
structure of arteries
-external layer of tough tissue
-middle layer containing elastic fibres and smooth muscle
-smooth lining allows easiest flow of blood
-lumen small when unstretched of blood
middle layer of arteries features
-contains elastic fibres and smooth muscle
-arteries nearest heart have more elastic fibres
-those further from heart have greater proportion of muscle tissue
adaptations of arteries near heart
a lot of elastic fibres so they can stretch to accommodate greater volume of blood without being damaged
-between surges elastic fibres return to original length squeezing blood and moving it in regular flow
peripheral arteries
-arteries further away from heart
-blood pressure drops
functionality of peripheral arteries
-muscle fibres in vessel walls contract or relax to change size of lumen
-controlling blood flow
what do capillaries link
arterioles and venules
features of capillaries
branch between cells
-substances diffuse between cells and blood quickly
-small diameter- blood travels slow- gives more time for diffusion to occur
adaptations of capillaries
-thin walls
-no elastic fibres, collagen, smooth muscle
-helps them fit between cells and quick diffusion
veins carrying blood
-carries blood back towards heart
-carries deox blood
pulmonary vein
carries oxygen rich blood from lungs back to heart for circulation around body
umbilical vein
during pregnancy
-carries ox blood from placenta to fetus
structure of veins
outer tough layer of collagen fibres
-thin layer of smooth muscle- few elastic fibres
-smooth inner surface
-large lumen
2 veins carry returning blood to heart
inferior vena cava- lower parts of body
-superior vena cava- upper parts of body