Tubular secretion is the transfer of materials from peritubular capillaries to the renal tubular lumen; it is the opposite process of reabsorption. This secretion is caused mainly by active transport and passive diffusion. Urine is the substance leftover in the collecting duct following reabsorption and secretion.Click to see full answer. People also ask, what is the site of tubular secretion? Location of Tubular Secretion In humans, and other vertebrates, tubular secretion occurs in the kidneys, where the blood is filtered in specialized structures known as nephrons. These structures consist of a long tubule surrounded by extensive capillaries. how does secretion occur in the nephron? Secretion. Secretion , which occurs in the proximal tubule section of the nephron , is responsible for the transport of certain molecules out of the blood and into the urine. Secretion occurs by active transport mechanisms that are capable of differentiating among compounds based on polarity. Also Know, why is tubular secretion important? Tubular secretion is important for: Controlling blood pH: hydrogen ions are secreted from the renal tubule cells into the filtrate to retain and generate more HCO3 (base). As a result the blood pH rises and the urine drains off the excess hydrogen ions.What is the difference between tubular reabsorption and tubular secretion?Secretion: substances secreted from blood into tubules. Reabsorption through passive or active transport from lumen of PCT into the peritubular capillaries.