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Stage 1 : Filtration
Blood enters the kidneys through the renal artery and is filtered by nephrons. Filtration happens in the glomerulus, where waste and extra fluids are separated from important substances that the body needs. -
Stage 2 : Reabsorption
After filtration, useful substances like glucose, amino acids, and water are reabsorbed back into the bloodstream. Reabsorption occurs primarily in the proximal tubule to ensure the body retains essential nutrients. -
Stage 3 : Secretion
During secretion, additional waste products and excess ions are secreted into the tubules. This step maintains the body’s acid-base balance by removing harmful substances. -
Stage 4: Excretion
The final stage involves excretion where waste and excess substances form urine. Urine travels from the kidneys through the ureters to the bladder and exits the body through the urethra.