Final answer:
The most correct and complete order of urine formation steps in a juxtamedullary nephron is Filtration, followed by Reabsorption, and then Secretion.
Step-by-step explanation:
The most correct and complete order of processes for the bulk formation of urine in a juxtamedullary nephron are: Filtration, Reabsorption, and Secretion. These processes take place sequentially starting with filtration. During glomerular filtration, blood that runs through the capillary network in the glomerulus is filtered, with solutes being filtered out while proteins largely stay in the bloodstream. The filtrate is then collected in the renal tubules, where tubular reabsorption occurs, primarily in the proximal convoluted tubule (PCT), loop of Henle, and peritubular capillary network. Most of the filtered solutes and water are reabsorbed back into the bloodstream during this step. Finally, during tubular secretion, additional solutes and wastes are secreted into the tubules of the kidney, essentially the reverse process of reabsorption. The filtrate, now modified into urine, is collected in the collecting ducts and exits the kidney through the ureters. Therefore, the most correct and complete order for processing urine is Option 1: Filtration, Reabsorption, Secretion.