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.
exists and is an alternate of . The fastest speed of a human running was set by Maurice Greene, who achieved a sprint speed of 26.7 mph. Note that is anarobic : the highest sustained speed is just over 15 miles an hour - i.e. a 4 minute mile. So the first is the limit of the legs, the second the limit of the heart.