Students examine the processes of diffusion and osmosis through the exploration of the physiology of hemodialysis. In the first experiment, students look at how the size of a particle affects diffusion. Students add NaOH and phenolphthalein to water and observe how they diffuse across a selectively permeable membrane (dialysis tubing). In the second experiment, students explore osmosis. They soak eggs in vinegar to remove the shell, leaving a selectively permeable membrane (similar to dialysis tubing). Then students use isotonic solution, a sugar solution (corn syrup), and deionized water to see how the tonicity of solutions leads to water movement across a membrane (i.e., osmosis).