Chapter 32: Structure and Function of the Kidney

The chapter explains how the kidney filters blood across the glomerulus, allowing water and small solutes to enter the Bowman's capsule while retaining large proteins and blood cells in the circulation. Students learn how antidiuretic hormone regulates aquaporin channels in the collecting duct to control water reabsorption, with clinical applications including the treatment of nocturnal enuresis in pediatric patients through ADH analog administration. The chapter emphasizes interpretation of key laboratory markers of renal function, particularly serum creatinine and blood urea nitrogen concentrations, which rise when glomerular filtration becomes compromised. Reduced nephron function manifests through polyuria and the production of dilute urine as the kidney loses concentrating capacity. The kidney's critical role in electrolyte homeostasis is explored, detailing how tubular reabsorption and secretion maintain potassium and calcium balance essential for cardiac and skeletal function. The chapter presents diagnostic approaches including calculation of estimated glomerular filtration rate as a noninvasive assessment of renal function, alongside direct visualization techniques such as cystoscopy for evaluating structural abnormalities of the urinary tract. Together, these concepts demonstrate how anatomical adaptations and regulatory hormones enable the kidney to perform its dual function of eliminating nitrogenous wastes while conserving essential nutrients and maintaining fluid-electrolyte balance.