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.
3) Tyson Gay: If it wasnât for Bolt, Gay would be the worldâs fastest human. Gayâs 9.69 is second only to Bolt and is a new American record and his 19.58 200-meters is third fastest ever. He recently became the first sprinter ever to run under 10 seconds in the 100, 20 seconds in the 200 and 45 seconds in the 400.