Complex sentence: This contrasts with macrocirculation, which transport blood to and from the organs, the microcirculation is composed by terminal arterioles, capillaries and venules which drain capillary blood.
Split into simpler sentences: This contrasts with macrocirculation, which is the circulation of blood to and from the organs. The microcirculation is composed of terminal arterioles, capillaries and venules which drain capillary blood.