ABSTRACT
The fundamental structural and functional organization of the nephron is conserved in the vertebrate kidney, and tissues with similar structure and function are observed throughout the animal kingdom. Direct measurements in animals have revealed that the hydrostatic pressure gradient across the glomerular capillary wall is normally about 45 mm Hg. Mechanical testing of basement membrane samples from kidney tubules indicates that this structure exhibits nonlinear mechanical properties, becoming stier as the strain is increased. Each kidney is capped by a closely approximated adrenal gland, each of which produces several important steroid hormones, including epinephrine and aldosterone. Fluids enter and exit the kidney through the hilum at the concave aspect of each organ. In the body, the hilum is oriented toward the abdominal great vessels. Upon penetrating the kidney at the hilum, the renal artery immediately branches into anterior and posterior divisions, and then arborizes into interlobar arteries that course radially between lobes of the parenchyma.
