Final answer:
During the process of tubular secretion, substances are transferred from the blood into the renal tubules, following glomerular filtration and tubular reabsorption, as part of urine formation.
Step-by-step explanation:
Urine Formation Process
During the tubular secretion process of urine formation, substances move from the blood into the renal tubules. This is part of a sequence of steps in kidney function that involves filtering blood to produce urine. Initially, glomerular filtration occurs in the glomerulus, where solutes are filtered out of the blood and into Bowman's capsule. Following this, filtrate collected in the renal tubules undergoes tubular reabsorption, where most of the solutes are reabsorbed into the blood. Lastly, in the tubular secretion phase, additional solutes and wastes that have not been reabsorbed are secreted into the renal tubules from the blood, completing the formation of urine.