Describe double circulation in mammals

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Deoxygenated  blood  from  body  tissues  (except  lungs);  enters  the  heart  via  the  right  auricle; through  the  venacava;  it  flows  to  the  right  ventricle;  via  the  tricuspid  valve;  the  right  ventricle contracts;  pumping  blood;  via  the  semi  lunar  valves;  through  the  pulmonary  artery;  to  the  lungs for  oxygenation;  the  oxygenated  blood  from  the  lungs;  flow  through  the  pulmonary  vein;  to  the left  auricle;  via  the  bicuspid  valve;  to  the  left  ventricle;  the  left  ventricle  contracts;  pumping blood  via  the  semi  lunar  valves;  through  the  aorta;  to  the  rest  of  the  body  tissues;  Max.  20  mks 

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