Urine is hypotonic in

Options

A. PCT
B. Loop of Henle
C. DCT
D. Cllecting duct

Answer

To determine where urine is hypotonic in the nephron, we need to analyze the functions of each segment of the nephron:

1. **Proximal Convoluted Tubule (PCT)**:
- The PCT is responsible for the reabsorption of water and solutes, including sodium chloride (NaCl).
- As water is reabsorbed along with solutes, the filtrate remains relatively isotonic, meaning it has a similar concentration of solutes compared to blood plasma.

2. **Loop of Henle**:
- The Loop of Henle has two limbs: the descending limb and the ascending limb.
- The descending limb is permeable to water but not to solutes, leading to the concentration of urine.
- The ascending limb is impermeable to water and actively transports NaCl out, which helps dilute the urine, but it does not create a hypotonic solution.

3. **Distal Convoluted Tubule (DCT)**:
- The DCT is primarily involved in the further reabsorption of sodium and water, but it also plays a role in the secretion of certain ions.
- By the time the filtrate reaches the DCT, it can be hypotonic due to the reabsorption of solutes without a corresponding reabsorption of water.

4. **Collecting Duct**:
- The collecting duct is where urine is concentrated or diluted based on the body's needs, influenced by hormones like ADH (antidiuretic hormone).
- The urine can become concentrated here, depending on the body's hydration status.

**Conclusion**:
- The urine is hypotonic in the **Distal Convoluted Tubule (DCT)** because this segment allows for the reabsorption of solutes without significant reabsorption of water, leading to a lower concentration of solutes in the urine.

### Final Answer:
Urine is hypotonic in the **Distal Convoluted Tubule (DCT)**.

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