Glomerular filtrate is a liquid that is formed in the kidneys by the process of filtration and is essentially a mixture of water, electrolytes, and small molecules such as glucose, amino acids, and urea. This filtrate passes through the glomerular capsule and enters the renal tubules, where additional processes of reabsorption and secretion occur and it is transformed into urine. Urine is the final product of filtration and consists of a concentrated mixture of waste products and other substances that are not reabsorbed or secreted by the renal tubules. Urine contains substances such as urea, creatinine, and potassium, as well as other electrolytes and metabolic waste products.