January 26, 2012
conflictingheart: inside the heart - Tissue-paper thin but tough, the valves of the human heart open and close to pump 6 quarts of blood a day through 60,000 miles (97,000 kilometers) of vessels. That’s equivalent to 20 treks across the United States from coast to coast.

conflictingheart:

inside the heart - Tissue-paper thin but tough, the valves of the human heart open and close to pump 6 quarts of blood a day through 60,000 miles (97,000 kilometers) of vessels. That’s equivalent to 20 treks across the United States from coast to coast.