connective The outer layer of a blood vessel (artery or vein) is called the tunica externa or tunica adventitia.See http://training.seer.cancer.gov/module_anatomy/unit7_3_ca â¦ rdvasc_blood1_classification.html pericardium is the layer of the blood vessel that is made of tough  connective tissue.onnective The outer layer of a blood vessel (artery or vein) is called the tunica externa or tunica adventitia.
As of June 2000, the fastest running human is Michael Johnson, the American track and field star who on August 1, 1996 set the world record of running 200 meters in 19.32 seconds.
Zach Bitter: Fastest 100-Miler In US History. Late last year Zach Bitter emerged as the fastest American in the history of long distance ultrarunning, setting an American record for 100 miles on a track in 11 hours and 47 minutes (roughly a 7 minute 4 second per mile pace) at Desert Solstice last December.