Heart

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  • Created by: LottieC
  • Created on: 31-03-14 15:42

Transport System

  • Carry raw materials from specialised exchange organs to body cells & remove waste
  • Too big to effictively carry out diffusion
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How is the heart adapted?

  • Left Ventricle is thicker because it needs to contract strongly to pump blood all around the body - right side only pumps blood to the lungs 
  • Ventricles have thicker walls than the atria - push blood out the heart 
  • Atrioventricular valves prevent backflow into atria when ventricles contact
  • Semi-Lunar Valve prevent backflow inot heart after ventricls contract 
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Valves

  • Valves only open one way - deependent on pressure
  • High pressure behind valve = open
  • High pressure in front of valve = closed
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Arteries

  • Carry oxygenated blood away from the heart at high pressure
  • Narrow Lumen
  • Thick walled - muscular, collagen & elsatic tissue to cope with high pressure
  • Endothelium folded- artery can expand = cope with high pressure
  • No valves
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Veins

  • Veins take deoxygenated blood to th heart at low pressure
  • Wide Lumen
  • Thin walls - little elastic or muscle tissue
  • Valves - prevent backflow
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Capillaries

  • Very narrow lumen
  • One cell thick wall - speeds up diffusion with substances
  • Network of capillaries = capillary bed
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Ventricular Diastole - Atrial Systole

  • Ventricles are relaxd
  • Atria contracts - decerasing volume in chamber & increasing pressure
  • Pushes blood into ventricles
  • Increase in ventricular pressure & volume as thy receive ejected blood from atria
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Ventricular Systole - Atrial Diastole

  • Atria relax
  • Ventricles contact - increases presuure
  • Atrioventricular valves shut - pressure difference
  • Semilunar valves forced open & blood forced into artries
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Diastole

  • Venticles & Atria both relax
  • High pressure in aorta & pulmonary artery closes SL vavle
  • Blood returns to heart & atria fills again
  • As ventricles relax - pressure dcreases = AV valves open 
  • Blood freely flows into ventricles 
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