The type of blood vascular system, in which blood flows inside blood vessels is called _____.
Closed
Blood vascular system or circulatory system of animals could either be open or closed in type. The type in which blood flow is confined to blood vessels (instead of freely flowing in open body spaces) is called closed blood vascular system. If blood is pumped by the heart (or equivalent organ) directly into the body spaces, rather than being circulated through blood vessels, it is known as open blood vascular system. This is mostly found in the lower organisms in the animal kingdom.