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.
Steve Edwards, a member of the 100 Marathon Club, set the world record for running 500 marathons in the fastest average finish time of 3 hours 15 minutes, at the same time becoming the first man to run 500 marathons with an official time below 3 hours 30 minutes, on 11 November 2012 at Milton Keynes, England.