Anatomy of the Kidney

Kidney, ureter, urinary bladder, and urethra are summarized as the excretory system or the urinary system. Based on its close developmental, anatomical and functional relations to the genital tract with its internal and external genital organs, the superior category of the genitourinary system or urogenital system has been established. The urinary system is understood as an organ system that produces, stores, and eliminates urine. Compared to other organs, the kidney characteristically reveals a complex array of interrelated morphological features and functional properties that challenges its investigator. This review focuses on the anatomy of the kidney. After a brief description of the gross anatomical features of the kidneys and their surroundings, a detailed review is presented on the functional morphology of the renal cortex, medulla, and pelvis. The renal vasculature with its gross features and specific wall architecture of the distinct arterial and venous segments is described in much detail. Correlative functional background is presented for the vascular segments. The different types of nephrons are explained and their anatomical segments analyzed in relation with their microanatomical position in defined zones of the cortical and medullary parenchyma. Models based on glomerular morphology and the recent discovery of gene products determining its functional integrity in health and disease are discussed. The epithelia along the course of the nephron and collecting duct system are presented with coverage of ion transporters, carriers, and channels and related major signaling pathways.