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VEINS

VEINS. By: Melissa, Gurleen , Simran , & Ravina. How Big Are They?. Veins are medium sized and thin Bigger than capillaries. Total Cross-sectional Area . Cross sectional area is medium sized compared to arteries except for the vena cava’s Lower than capillaries equal to arteries

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VEINS

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  1. VEINS By: Melissa, Gurleen, Simran, & Ravina

  2. How Big Are They? • Veins are medium sized and thin • Bigger than capillaries

  3. Total Cross-sectional Area Cross sectional area is medium sized compared to arteries except for the vena cava’s Lower than capillaries equal to arteries lower than arterioles and venules

  4. Blood Velocity Blood Pressure lowest in veins • low because blood is returning to the heart and has lost some of the pressure. with which it was pumped out of the heart

  5. Direction of Blood Flow Veins move blood from organs back towards the right atrium of the heart, and from the lungs

  6. Valves? • Does have valves, which allow blood to flow only toward the heart when open and prevent the backward flow of blood when closed • Found in veins that carry blood against the force of gravity

  7. Wall of Veins • Three layers that have less smooth muscle and connective tissue than arteries • 3 layers Inner layer: is called endothelium and contains elastic fibers Middle layer: thickest and consists of smooth muscle that regulates blood flow Outer layer: fibrous, connective tissue near the middle layer and becomes loosely connected • Thinner walls • Can expand to a greater extent

  8. The blood in veins is deoxygenated except for pulmonary veins, which carry oxygenated blood from the lungs back to the heart

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