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.
On April 18, 2011, Geoffrey Mutai of Kenya ran the second fastest marathon ever in a time of 2:03:02, albeit on the Boston course, which does not meet the criteria for record attempts. Countryman Moses Mosop ran the third fastest time ever (2:03:06) on the same course and day as Mutai.