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cardiovascular disease

  • diseases of heart and blood vessels 
  • build up of fatty deposits in artery walls leading to atheromas ---> partially block the lumen 

4 common CVD's

  • High blood pressure: (atheromas, bad diet...) lead to other CVDs as blood clots likely to form 
  • Stroke: blood clots artery that supplies blood to the brain- brain tissue damaged by lack 
  • CHD: coronary arteries are blocked by atheromas so heart doesnt get much blood 
  • Heart attack(myocardial infarctions): coronary artery totally blocked so no blood through 
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blood vessels

  • Arteries ---> away from heart 
  • arterioles ---> from arteries 
  • capillaries ---> join to form veins 
  • veins ---> return blood to heart 

arteries are elastic

  • think wall compared to diameter of lumen 
  • outer layer of fibrous tissue ---> thick layer of elastic tissue + smooth muscle --->thin inner layer of folded endothelial tissue 
  • ventricles contract + blood nter at high pressure stretching endothelial tissue 
  • venticles relax ---> elastic recoils keeping pressure up 

arterioles can contract 

  • narrower + higher proportion of smooth muscle fibres to elastic tissue 
  • muscle fibres contract ---> diameter of lumen reduced ---> less blood flows ---> control amount 
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blood vessels part 2

capillaries

  • capillary walls consist of single layer endothelial cells with tiny gaps between 
  • thin walls + gaps allow substances to diffuse quickly 
  • thousands of tiny capillaries = large SA:vol 
  • blood flows slowly through them ---> more time for diffusion 

veins have valves 

  • large lumen, raltively thin wall with little elastic tissue + smooth muscle 
  • valves prevet backflow 
  • leg muscle contracts helping press on veins + blood returns to heart quicker 
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blood

haemoglobin- a protein that contains iron + carries oxygen 

  • with oxygen it forms oxyhaemoglobin 
  • lots of O2 ---> one molecule fo hae. combines with 4 O2 molecules (fully saturated)
  • less O2 ---> (less than 100% saturated)
  • becomes fully sat. around alveoli in lungs as higher concen. of O2 
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