The<unk>  is an organ system that moves nutrients, gases, and wastes to and from cells, helps fight diseases and helps stabilize body temperature and pH to  maintain homeostasis. This system may be seen strictly as a blood distribution network, but some consider the<unk>  as composed of the cardiovascular system, which distributes blood, and the lymphatic system, which distributes lymph.  While humans, as well as other vertebrates, have a closed cardiovascular system (meaning that the blood never leaves the network of arteries, veins and capillaries), some invertebrate groups have an open cardiovascular system. The most primitive animal phyla lack<unk> s.  The lymphatic system, on the other hand, is an open system.
Circulatory system
Cerebral circulation
Autonomic nervous system
Coronary circulation
Cardiac cycle
Sympathetic nervous system
Lymph vascular system
Systemic circulation