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The Heart

pump blood around the body continuously so much of the wall is muscle tissue
coronary artieries - supply oxygen glucose for fuel ...if blocked cause heart atttack
4 chambers----- right artium (top chamber) and left atrium .... right ventricle (bottom chamber and left ventricle
artia fill up... then atria contract and force blood into ventricles... then ventricles contract and force blood out ... and there are valves that shut to make sure blood flows in the right direction
circulatory system transports substances around the body - consists of heart...blood vessels....blood
Blood Vessels
1. Arteries- take blood from heart to organs
  1. artery --- layer of muscle and layer of elastic tissue create thick wall essential as there is alot of high pressure blood flow (small lumen)
    1. if arteries begin to narrow and restrict blood flow then small mesh tubes called stents can be inserted to widen artery to keep open to restore blood flow to heart
2. viens - take blood from organs to heart
  1. have thinner walls and valves to prevent backflow (large lumen)
3. The Blood
  1. red blood cells and white blood cells and platelets
    1. red blood cells transport oxygen..... dont have nucleus so they have more room for haemoglobin that carries oxygen ( oxyhaemoglobin) is haemoglobin that is exposed to oxygen in the lungs ... after gone to cells around body splits back into oxygen and haemoglobin. that oxygen is then used by cells for respiration
      1. lungs - haemoglobin + oxygen = oxyhaemoglobin
      2. other organs - oxyhaemoglobin can be broken back to haemoglobin and oxygen
    2. white blood cells - defend the body against microorganisms and bacteria ( immune system)
    3. platelets are fragments of cells -- help the blood to clot when there has been a cut...... platelets block the wound and dont have a nuclus
  2. plasma-- straw coloured liquid ( red from lots of red blood cells suspended in the liquid)transports carbon dioxide from the organs to the lungs and soluble products eg sugars and amino acids in the small intestine absorbed into plasma and transported to organs
  3. urea - produced in the liver made from extra amino acids broken down in liver to form urea and then urea is transported in plasma to the kidney swhich then filter the urea and taken out the body throught urine
4. Capillaries - are narrow and thin walled blood vessels
  1. allow substances needed by cellls to pass out of the blood
    1. allows substances produced by cells to pass into blood
  2. one cell thick -- diffuse soluble foods like glucose and pick up of gas for respiration..from the blood to the cells..one blood cell at a time.....smallest blood vessel
5. higher pressure in arteries than viens
blood pumped into lungs so carbon dioxide can be exchanged for oxygen
1. oxygenated blood - provides glucose and oxygen to cells
2. deoxygenated blood takes away waste products including carbon dioxide, urea
blood passes through the heart twice.... 1) to carry blood from the heart to the lungs and back to the heart ..... 2) carry blood from the heart to other organs and back to the heart
Right side pumps blood which is low in oxygen to the lungs to get oxygen whilst the left side pumps blood which is rich in oxygen to other parts of the body
leaking valves can be replaced by a donor or mechanical valve.......articfical pacemakers can be fitted if there is an irregular heart beat affecting circulation of blood. Risk of infection, size of component nad power supply are proiblems with mechanical / electrical heart components

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	Created by dpatel383 over 11 years ago