1786999
Description
Flashcards by Camilla Donaldson, updated more than 1 year ago
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Created by Camilla Donaldson
over 9 years ago
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| Question | Answer |
| What does it mean by double circulation? | It involves two circulatory systems, in which there are two loops in which blood circulates. As once circuit links the heart and lungs, while the other circuit links the heart with the rest of the body. |
| What is pulmonary circulation? | Carries deoxygenated blood from the heart to the lungs (via pulmonary artery) to be oxygenated, then carries this oxygenated blood back to the heart (via the pulmonary vein). |
| What is the advantage of these separate circulatory systems? | -It ensures that the oxygenated and deoxygenated blood does not mix, so that tissues receive maximal oxygen. -Also fully oxygenated blood can be delivered to quickly to body tissues as high pressure. |
| What is the role of arteries? | Arteries carry blood away from the heart, almost all arteries carry oxygenated blood except for the pulmonary artery, and during pregnancy the umbilical artery carries deoxygenated blood from the foetus to the placenta. |
| How does the structure of the arteries help it to withstand the high pressure exerted by the heart? | -the elastic fibres in their walls stretch and recoil to accommodate to the blood pressure and keep it high. -the smooth lining of the lumen ensures easiest possible flow of blood. -The muscles in the wall contract to exert the pressure as it changes the size of the lumen, as the smaller the lumen the harder it is for blood to flow |
| What is the role of the capillary? | To link the arterioles and venules, as they form dense networks around cells and vital organs to allow rapid diffusion of substances from the blood to the cells. |
| How does the structure of capillaries relate to its function? | Capillaries have very thin walls which are one cell thick, containing no elastic fibres, collagen or muscle. Allowing rapid diffusion of substances between the blood and the cells. |
| What are the functions of veins? | Veins carry deoxygenated blood back to heart, except for in the pulmonary circulation when veins carry oxygenated blood back to heart and during pregnancy when the umbilical vein carries oxygenated blood from the placenta into the foetus. |
| What is the inferior vena cava? | A major vein which carries deoxygenated blood from the lower body back to the heart. |
| What is the superior vena cava? | A major vein which carries deoxygenated blood from the upper parts of the body back to the heart. |
| The blood at low pressure has to be returned to heart, how is this achieved? | -At frequent intervals throughout the venous system there are one way valves, if the blood starts to flow backwards the valves close. -since many of the larger veins are situated between major muscles, as the muscles contract (especially during physical activity) they squeeze the veins helping the blood to return to the heart. |
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