The cardiovascular system in all vertebrates consists of the heart and blood vessels. Lacteals are part of the lymphatic system. Open Vs Closed Circulatory System Biology Dictionary Lymphatic System comprises a fluid known as lymph lymph capillaries and lymph ducts. . A medical laboratory is a laboratory where specimen samples are stored examined and processed. Blood and interstitial fluid are distinct. Present in molluscs and arthropods. It is an extension of the circulatory system. Open circulatory systems use hemolymph instead of blood. The circulatory system includes the heart blood vessels and blood. The circulatory system is further divided into two major circuits a pulmonary circulation and a systemic circulation. In the closed circulatory system blood flows through a closed system of chambers the heart and blood vessels. The lymphatic system or lymphoid system is an organ system in vertebrates that