Think big when you think about me. I am a transport system with 1,12000 kilometers of route – more than a global airline.I am also a garbage man and delivery boy with 60 trillion-customers that is 17,000 times the number of people there are on earth. My customers are the cells in my body. I haul away their wastes and provide them with the essentials of life. I am yours blood stream.You think of me as a sluggish river, and is hardly aware of the frenzied activity under way within me at all times. In the second it takes me to blink his eyelids, 1.2 million of my red cells reach the end of their 120-day lie span and perish.In that same second, my marrow, mostly in your ribs, skull and vertebrae, produces an equal number of new cells. In a lifetime these bones will manufacture about half a ton of red cells.During its short life, each red cell will make something like 75,000 round trips from your heart to other parts of his body.