As discussed earlier in Chap. 1 , hollow organs like the heart, lungs, airway, blood vessels, and urinary bladder that contain fluids (air, blood, urine) are routinely subjected to changes in both HP and cyclic stretch simultaneously through daily physiological functions of those organs. In the past few decades, many researchers have examined the effects of cyclic stretching on cells from lungs and bronchi (epithelial cells, smooth muscle cells), and urinary bladder (urothelial cells, smooth muscle cells). To a lesser extent, investigators also examined the effects of physiological level HP on these cells. The differences in the amount of data available between cyclic stretch and HP studies are partly due to the availability of commercial devices that allow investigators to subject cultured to cells to controlled stretching. In this chapter, we will review the anatomy, physiology, and cellular composition to explore the biomechanical environment of the cells of these organs. We will then review the in vitro studies that aim to understand the role of cyclic stretch and HP in pathological conditions experienced by these organs.