The lowest osmotic potential inside a nephron will be found in __________.

• A. Bowman's capsule and the proximal tubule
• B. the descending limb of the loop of Henle
• C. the loop of Henle
• D. the collecting duct
• E. the thick segment of the ascending limb of the loop of Henle and the distal tubule

Answer: (E)

Verified step by step guidance

1. Understand that osmotic potential refers to the tendency of water to move across a semipermeable membrane. In the nephron, this is influenced by solute concentration gradients.
2. Recognize that the loop of Henle plays a crucial role in creating a concentration gradient in the medulla of the kidney, which is essential for water reabsorption.
3. Identify that the descending limb of the loop of Henle is permeable to water but not to solutes, leading to an increase in solute concentration and a decrease in osmotic potential as water exits.
4. Note that the thick segment of the ascending limb of the loop of Henle is impermeable to water but actively transports ions out, decreasing the solute concentration inside the nephron and increasing osmotic potential.
5. Conclude that the lowest osmotic potential, meaning the highest solute concentration, is found in the thick segment of the ascending limb of the loop of Henle and the distal tubule, as these areas are involved in the active transport of ions, reducing solute concentration and increasing osmotic potential.