KIN 272 Lecture 1: Blood Vessels

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KIN 272
Jennifer Gordon

Blood Vessels • Arteries- move blood away from the heart o Pulmonary arteries do not contain oxygenated blood • Veins- take blood towards the heart o Pulmonary veins carry oxygenated blood • Not all Arteries and Veins carry oxygenated and deoxygenated blood • Arteries and veins are composed of three layers o Tunica intima- inside most layer ▪ Made up of epithelial cells ▪ Thickness depends on the location and size of arteries and veins o Tunica media- middle layer ▪ What allows the different arteries to be distinguished o Tunica externa- outside most layer • Arteries: -Flow slows down from elastic to capillary because there is a larger area to cover -Good that blood flow is slower in capillary because there would be time to diffuse; no time for exchange if flow is fast o Elastic ▪ 90% tunica media of elastic fibers ▪ 10% smooth muscle ▪ Can snap back if stretched ▪ Aorta sized o Muscular ▪ 50% elastic fibers ▪ 50% muscular ▪ Can partially contract and snap back if stretched ▪ Arteries that branch from aorta such as, brachial, femoral, superior mesenteric o Arteriole ▪ 10% Elastic ▪ 90% smooth muscle ▪ Can contract and dilate; can change diameter ▪ Branches off of muscular o Capillary • Veins: -Tunica media can barely be seen, minimal -Tunica intima is bigger than tunica media sometimes or not even seen; mostly collagen fibers and some elastic -Majority of the vein is tunica externa -No smooth muscle 90%, have like 1-4% smooth muscle- can’t really contract or change; main difference between arteries and veins -Have one way valve: allows blood to move in one direction and shuts when try to go backwards; no smooth muscle to dictate flow so valve is present -oval shaped because no muscle cells to form well structure o Veinules ▪ Extensions of the capillary o Small veins o Medium veins o Vena cava Resistance to Flow (Q) - Total peripheral Resistance (TPR) – anything in the periphery outside the heart that causes opposition to flow o Push back blood to the heart and causes heart to work harder o If ongoing, can cause an illness in the heart- poor functioning heart due to overworking o Vessel length: Increase vessel length  decrease flow; increases resistance and there’s a reduction in flow ▪ Vessel length cannot be controlled o Vessel diameter: Increase diameter  increase flow; decreases resistance ▪ Greatest impact; can impact resistance up to 4 folds, 4 time effect, 4 time greater than other resistance aspects ▪ Vessel has the ability to change shape which contributes to resistance the most o Viscosity: increase viscosity  decrease flow; increase resistance o Turbulence: increase turbulence  decrease flow ▪ Turbulant flow • Not forward moving in one direction, juggle around and has swirls • Undertow of the ocean • Created because part of the vessel wall isn’t uniform so build up might occur • Also occurs where the vessel splits like a fork • Happens frequently ▪ Laminar flow • Fluid is moving through tube unrestricted, moving in good phase • Has a parabolic shape: flui
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