composed primarily of Homo sapiens Homo sapiens protein-containing material entity vein venous system MA:0002720 VHOG:0000277 UMLS:C1267406 EHDAA2:0002171 uberon The part of the cardiovascular system consisting of all venous vessels. In vertebrates with a double circulation, this can be divided into systemic and pulmonary portions. NCIT:C33858 The appearance of Chordata and subsequently the vertebrates is accompanied by a rapid structural diversification of this primitive linear heart: looping, unidirectional circulation, an enclosed vasculature, and the conduction system.[well established][VHOG] UBERON:0004582 vein system SCTID:362060003 EMAPA:16240 BTO:0004692 EHDAA:486 vascular system