Drug transport by fluid motion

William Wordsworth, Lines composed a few miles above Tintern Abbey, on revisiting the banks of the Wye during a tour, July 13, 1798 

The rate of molecular movement by diffusion decreases dramatically with distance, and is generally inadequate for transport over distances greater than 100/rm (recall Table 4.8). The movement of molecules over distances greater than 100 jxro. occurs in specialized compartments in the body blood circulates through arteries and veins interstitial fluid collects in lymphatic vessels before returning to the blood cerebrospinal fluid (CSF) percolates through the central nervous system (CNS) in the brain ventricles and subarachnoid space. In these systems, molecules move primarily by bulk flow, or convection. 

Biomedical engineers have long studied the circulatory system and made essential contributions to our understanding of cardiovascular physiology [1, 2]. 

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