Date post: | 17-May-2015 |
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Technology |
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Blood Vessels
Lloyd Dean
NVQ Level 3 Personal Training
AimsBy the end of the lesson you should be able
to:
Describe the structure of the different blood vessels
Describe the function of each of the different blood vessels
Create a blood vessel comparison table
Structure of Blood Vessels
Structure of LayersTunica Externa / AdventitiaOuter layerLargely made up of collagen and elastin fibersSupports blood vessel by being shock absorber
Tunica MediaMiddle layerMainly smooth muscle with elastic layers and collagenUsed for vasoconstriction and vasodilation
Tunica IntimaComposed of smooth epithelial cells named
endotheliumMinimises friction between moving blood
Artery / ArteriolesArteriesPumps oxygenated blood to the bodyHave narrow lumensStrong as pumping blood at high pressure
ArteriolesBranches into smaller arteries (arterioles)
when nearer tissueMore smooth muscle to control blood flow
CapillariesThinnest blood vesselMade of single layer endothelial cellsBring blood as close as possible to all cellsExchange of oxygen, carbon dioxide, water,
salts, between the blood and the surrounding body tissues takes place
Large quantities cover the muscle, ensuring efficient exchange of gases
Veins / VenulesVenulesVessels formed from capillariesDrains blood from capillaries into veins
VeinsHave same walls as artery but less thinner,
elastic and muscularPressure and speed of blood is lowWider Lumen than arteryHave valves that prevent backflow of blood
Comparison of Blood VesselsFeature Artery Capillary Vein
Tunica Externa √ X √
Tunica Media Thick X Thinner
Tunica Interna √ √ √
Size of Lumen Small Microscopic Large
Valves X X √
AimsYou should now be able to:
Describe the structure of the different blood vessels
Describe the function of each of the different blood vessels
Create a blood vessel comparison table