Urinary tubules, also called renal tubules, are tiny tubes within the kidneys that play a crucial role in filtering blood and forming urine, reabsorbing essential substances, and eliminating waste. 

The urinary tubules of the kidney function through ultrafiltration and selective reabsorption to form urine. In the glomerulus, blood is filtered under pressure, forcing small molecules like water, electrolytes, glucose, and urea into the Bowman's capsule, forming the glomerular filtrate. As the filtrate flows through the renal tubules, the body selectively reabsorbs essential substances like water, glucose, amino acids, and electrolytes back into the bloodstream, while waste products remain in the filtrate to be excreted as urine.