Question

Identify the correct statement:

• A. The ascending limb of Henle’s loop is impermeable to water.
• B. The ascending limb of Henle’s loop is permeable to water.
• C. The descending limb of Henle’s loop is permeable to electrolytes.
• D. The descending limb of Henle’s loop is impermeable to water.

Hint:

Remember: Descending limb = water permeable; Ascending limb = solute permeable, water impermeable.

Answer 1

The Correct Option is A

The loop of Henle plays a crucial role in the concentration of urine and maintaining osmotic balance:
- The descending limb of Henle’s loop is permeable to water but impermeable to solutes (electrolytes).
- The ascending limb is impermeable to water but actively transports Na\textsuperscript{+}, K\textsuperscript{+}, and Cl\textsuperscript{–} into the medullary interstitium.
Therefore, the correct statement is:
- "The ascending limb of Henle’s loop is impermeable to water."

Answer 2

The nephron is the functional unit of the kidney and plays a key role in the process of urine formation and the regulation of water and electrolyte balance in the body. A critical part of the nephron is the Loop of Henle, which consists of a descending limb and an ascending limb, each with distinct permeability properties.

The ascending limb of Henle’s loop is impermeable to water, meaning that water cannot pass through its walls. Instead, this segment actively transports sodium and chloride ions out of the filtrate into the surrounding medullary tissue, which helps create a concentration gradient essential for water reabsorption later in the nephron. This property is vital for the kidney's ability to concentrate urine and maintain the body's fluid balance.

In contrast, the descending limb is permeable to water but less permeable to solutes, allowing water to be reabsorbed by osmosis, concentrating the filtrate as it moves down.

Thus, the correct statement is that the ascending limb of Henle’s loop is impermeable to water.