Inside the Kidney’s ‘Countercurrent’ Mystery: A New Model for Teaching and Studying Water Balance

Our kidneys filter blood to remove waste and can regulate water balance. We’ve all experienced that when we're thirsty urine becomes concentrated, signalling us to drink more water. When we drink excess water, we urinate more frequently, and the urine is diluted. The kidneys’ ability to concentrate or dilute urine according to our body’s need relies on countercurrent multiplication (or CCM), a complex process that generates a salt concentration gradient in the kidney. However, CCM is challenging to teach and understand. Dr. Serena Kuang, a researcher and educator at Oakland University William Beaumont School of Medicine, has developed a more understandable CCM model and clears up errors in existing explanations making CCM easier to understand and teach.