Which one is the diluting segments of uriniferous tubule ?

Options

A. Ascending loop of Henle
B. Descending loop of Henle
C. PCT
D. DCT

Answer

To determine which segment of the uriniferous tubule is the diluting segment, we can analyze the functions of the different parts of the nephron. Here’s a step-by-step solution:

### Step 1: Understand the Structure of the Nephron
The nephron is the functional unit of the kidney and consists of several segments: the Proximal Convoluted Tubule (PCT), Loop of Henle (which includes the descending and ascending limbs), and the Distal Convoluted Tubule (DCT).

**Hint:** Familiarize yourself with the structure and function of each part of the nephron.

### Step 2: Analyze the Function of Each Segment
- **Proximal Convoluted Tubule (PCT):** Primarily involved in the reabsorption of water, ions, and nutrients.
- **Descending Loop of Henle:** Permeable to water but not to solutes; it concentrates the urine as water is reabsorbed.
- **Ascending Loop of Henle:** Impermeable to water but actively reabsorbs solutes (Na+, Cl-), leading to dilution of the tubular fluid.
- **Distal Convoluted Tubule (DCT):** Further adjusts the composition of urine but is not primarily a diluting segment.

**Hint:** Focus on the permeability and reabsorption characteristics of each segment.

### Step 3: Identify the Diluting Segment
The ascending limb of the Loop of Henle is responsible for actively reabsorbing solutes while being impermeable to water. This results in a decrease in the concentration of the tubular fluid, effectively diluting it.

**Hint:** Remember that a segment that actively removes solutes without allowing water to follow will dilute the fluid.

### Step 4: Conclusion
Based on the functions analyzed, the ascending Loop of Henle is the diluting segment of the uriniferous tubule, as it reduces the osmolarity of the tubular fluid from a higher concentration to a lower concentration.

**Final Answer:** The diluting segment of the uriniferous tubule is **A. Ascending Loop of Henle**.