Final answer:
Tubular reabsorption primarily occurs in the proximal convoluted tubule (PCT), which reabsorbs solutes and water from the filtered urine using active transport and a high surface area created by microvilli.
Step-by-step explanation:
Tubular reabsorption primarily occurs in the proximal convoluted tubule (PCT). This part of the nephron is responsible for recovering most of the filtered solutes and water from the urine. The proximal convoluted tubule is characterized by its twisted structure and the presence of microvilli, which greatly increase the surface area for reabsorption and secretion processes. These cells actively transport ions, requiring a significant amount of ATP, hence the presence of numerous mitochondria. In conjunction with the PCT, the loop of Henle, distal convoluted tubule (DCT), and collecting ducts also contribute to reabsorption and hormonally regulated fine-tuning of water and electrolyte balance.
The loop of Henle plays a role in concentrating the urine, the DCT recovers an additional portion of water and solutes, and the final adjustments in water recovery or disposal occur in the collecting ducts, where they are influenced by hormones such as aldosterone.