The urine formation process can be divided into three main steps:
1. Glomerular Filtration: Blood enters the glomerulus, a network of capillaries, where it is filtered. The filtration barrier, composed of endothelial cells, basement membrane, and podocytes, allows water and small solutes to pass while retaining larger molecules like proteins and blood cells.
2. Tubular Reabsorption: The filtrate, now called glomerular filtrate, moves into the renal tubules. Here, essential substances such as glucose, amino acids, and ions are reabsorbed by the epithelial cells lining the tubules and returned to the bloodstream.
3. Tubular Secretion: In this step, additional waste products and excess ions are secreted from the blood into the tubular fluid. This process helps in maintaining the body's electrolyte balance and pH levels.
