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4 Cards in this Set
- Front
- Back
Artery & Arterioles |
●blood at high pressure due to contraction of left ventricle ●carry blood from heart to rest of the body ●divide into smaller arterioles which forms a network through the body ●small lumen to maintain blood pressure ●collagen fibres & fibrous proteins means thick wall can withstand high pressure ●elastic tissue allows wall to stretch & recoil which maintains diastolic pressure ●smooth endothelium to reduce friction & folded so can unfold when artery stretches ●S.muscle allows contraction & vasoconstriction this narrows the lumen of artery In arterioles,muscle enables blood to be directed to diff areas of demand in the body Muscle contracts to restrict blood flow and relaxes to allow full blood flow |
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Veins & Venules |
●Lowest blood pressure from all vessels ●carry blood back to heart ●lumen large to ease flow of blood ●walls have less collagen,smooth muscle & elastic tissue as they do not perform role if the artery ●wall is thin but still strong ●valves prevent backflow of blood ●to move blood through the veins back to the heart pressure is exerted by the movement of the muscles There is also some residual pressure from the contraction of the left ventricle muscle wall |
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Capillaries |
●blood has high pressure at arteriole end due to contraction of left ventricle but falls towards the venous end ●Arterioles branch into capillaries,smallest of blood vessels ●walls made up of single layer of flattened endothelial cells which reduces diffusion distance ●narrow lumen same diameter as a red blood cell so squeezed which reduces diffusion distance ●smooth endothelium reduces friction for blood flow ●gaps between endothelial cells allow movement of nutrients,proteins cannot pass ●large total surface area for more exchange |
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Pressure changes in blood vessels |
Top-Contraction of the left ventricle wall creates high pressure Bottom-Relaxation of left ventricle wall & elastic recoil of stretched arteries maintains pressure |