Tubular reabsorption and secretion
Tubular reabsorption and secretion are important processes that occur in the kidneys to maintain the balance of electrolytes and fluids in the body. Tubular reabsorption occurs when the kidneys reabsorb useful substances, such as glucose, amino acids, and electrolytes, from the filtrate back into the bloodstream. This process occurs primarily in the proximal tubule of the nephron and is critical in maintaining the body's electrolyte and fluid balance. Tubular secretion is the opposite process, where the kidneys secrete waste products, such as excess potassium or hydrogen ions, from the bloodstream into the tubular fluid. This process occurs primarily in the distal and collecting tubules of the nephron.