Artery large A: aorta, pulmonary trunk medium-sized A: all named A, the diameter> 1mm(radial a, ulnar A) smalla 300um< d<lmm2. Artery ---large A: aorta, pulmonary trunk ---medium-sized A: all named A, the diameter > 1mm(radial A,ulnarA) ---small A: 300um<D<1mm