An Overview of Renal Physiology

Abstract

The kidney is responsible for varied and critical functions that maintain homeostasis (this can be seen in Table 7.1, which demonstrates the excretory capacity of the kidney). These functions include maintaining the volume and composition of the extracellular fluid (despite drastic and variable difference in daily intake), removal of toxic waste products (such as the end-products of metabolism such as urea, phosphates, sulfates, and uric acid), the conservation of essential nutrients (glucose, amino acids, electrolytes), regulation of acid–base balance, production of hormones (active 1,25-vitamin D and erythropoietin), regulation of blood pressure, and the excretion of drugs that are metabolized. In order to achieve these functions, the kidney acts as an integrative organ of its constitutive parts: the nephrons. There are approximately 1.2 million nephrons per kidney at birth and it is the function of these units that controls homeostasis.