What is nephron?

Each kidney in a human contains millions of nephrons. Nephron is the basic structural and functional unit of the kidney.  Kidneys contain two types of nephrons: cortical nephrons and juxtamedullary nephrons, which are located in different parts of the renal cortex. A nephron is composed of a renal corpuscle, a renal tubule, and the associated capillary network.
The main function of nephron is to regulate the concentration of water and soluble substances like sodium salts by filtering the blood, reabsorbing what is needed and excreting the rest as urine. A nephron eliminates wastes from the body, regulates blood volume and blood pressure, controls levels of electrolytes and metabolites, and regulates blood pH.  The hormones like antidiuretic hormone, aldosterone, and parathyroid hormone are mainly helps in regulating these functions. In humans, a normal kidney contains 800,000 to 1.5 million nephrons.