Every single day, without you noticing or doing anything at all, roughly 180 litres of fluid are filtered out of your blood, checked over in extraordinary detail, and almost all of it quietly returned. This episode explains what the kidneys actually do, how the microscopic filtering units called nephrons manage filtration and reabsorption at the same time, why kidneys are central to controlling blood pressure and the body's salt and water balance, why the concentration of urine matters, and what's really happening in kidney disease, dialysis and transplantation.

You'll come away understanding what a nephron is and how it filters blood, the difference between filtration and reabsorption, how the kidneys help regulate blood pressure through salt and water balance, why urine can range from almost clear to deep yellow, what actually goes wrong  ...