Specialised tubes - arteries, capillaries and veins.
All tubes are composed of living cells.
The concentration of substances transported is controlled (see homeostasis).
The heart controls the circulatory system. The heart is controlled by the nervous system.
The rate of flow is moderate and is regulated by vasoconstriction and vasodilation.
Uses water as a medium in which to transport substances (it is a good solvent, it has a high specific heat capacity, has good surface tension but is not viscous, and is unreactive).
The substances being transported…