Transport systems in multicellular organisms

The biological success of the multicellular body plan lies in its capacity for tissue differentiation and specialisation of function. Differentiated organs and tissues, in fulfilling their specialised activities on behalf of the whole organism, cannot act autonomously. The functions are co-ordinated (Part V) to provide an integrated response to the needs of the organism. A further feature of the differentiated organism is the presence of a transport system which carries metabolic substrates to the cells of the organism and likewise distributes metabolic products. In animals the transport function is carried out primarily by the blood system and in higher plants by xylem and phloem.