thank you.🌝

http://wiki.answers.com/Q/Where_does_the_production_of_red_blood_cells_take_place


http://www.psbc.org/hematology/02_how.htm


http://www.physicsforums.com/showthread.php?t=388233


http://health.howstuffworks.com/human-body/systems/circulatory/heart-pump-blood1.htm


https://answers.yahoo.com/question/index?qid=20081202163223AA8qmUv


http://www.ask.com/question/blood-pathway-through-the-heart


http://www.fi.edu/learn/heart/blood/red.html


http://www.healthhype.com/red-blood-cells-functions-size-structure-life-cycle-pictures.html