ENGINEERING APPROACHES TO UNDERSTANDING THE KIDNEY

In this chapter, kidney physiology is singled out as an exemplar of how engineering methods shape the laws of motion, thermodynamics, and control theory into applicable techniques for the biologist. It is the role of kidneys to stabilize the volume and composition of the body fluids against outside disturbance. This is accomplished by generating a large volume of ultrafiltrate from plasma in the renal glomeruli, then subjecting the ultrafiltrate to extensive modification by the renal tubules to form a final urine that matches the dietary intake. A brief overview is provided of the various kidney functions, followed by a description of how engineering approaches have been central to our understanding of glomerular ultrafiltration, basic tubular reabsorption, the countercurrent multiplier system for enabling a concentrated urine, and internal negative feedback controllers that stabilize kidney function.