Renal physiology is the study of how the kidneys function to maintain the body's internal environment. The kidneys filter blood, removing waste products and excess substances, which are then excreted as urine. They also regulate important factors like blood pressure, electrolyte balance, and acid-base balance. The kidneys perform these functions through processes such as filtration, reabsorption, and secretion. In the nephrons, the functional units of the kidneys, blood is filtered, and essential nutrients and water are reabsorbed back into the bloodstream. This intricate system helps ensure that the body remains in homeostasis.