Find the correct match of site and function of nephron

Options

A. `{:("SITE","FUNCTION"),("DCT","Reabsorption of "Na^(+)" and "K^(+)" from filtrate"):}`
B. `{:("SITE","FUNCTION"),("Descending of loop of Henle","Impermeable to water"):}`
C. `{:("SITE","FUNCTION"),("PCT",HCO_(3)^(-)" absorption of filtrate"):}`
D. `{:("SITE","FUNCTION"),("DCT","Massive reabsorption of "H_(2)O" & "H^(+)","K^(+)" ions"):}`

Answer

To find the correct match of site and function of nephron, we need to analyze each option provided in the question. The nephron is the functional unit of the kidney and consists of several parts, each with specific functions.

### Step-by-Step Solution:

1. **Identify the Components of the Nephron**:
- The nephron consists of the Bowman's capsule, proximal convoluted tubule (PCT), loop of Henle (which includes the descending and ascending limbs), distal convoluted tubule (DCT), and collecting duct.

2. **Evaluate Option 1**:
- **Site**: Distal Convoluted Tubule (DCT)
- **Function**: Reabsorption of sodium and potassium from filtrate.
- **Analysis**: While sodium reabsorption does occur in the DCT, potassium is typically secreted rather than reabsorbed. Therefore, this option is **incorrect**.

3. **Evaluate Option 2**:
- **Site**: Descending Loop of Henle
- **Function**: Impermeable to water.
- **Analysis**: The descending loop of Henle is actually permeable to water, allowing water to exit into the surrounding medulla. Thus, this option is **incorrect**.

4. **Evaluate Option 3**:
- **Site**: Proximal Convoluted Tubule (PCT)
- **Function**: Absorption of sodium by hydrogen bicarbonate from filtrate.
- **Analysis**: The PCT is responsible for the reabsorption of various substances, including sodium and bicarbonate ions. This option is **correct**.

5. **Evaluate Option 4**:
- **Site**: Distal Convoluted Tubule (DCT)
- **Function**: Massive reabsorption of water, hydrogen ion, and potassium ion.
- **Analysis**: While the DCT does reabsorb water, it does not massively reabsorb hydrogen ions or potassium ions; instead, it typically secretes them. Thus, this option is **incorrect**.

### Conclusion:
Based on the evaluations, the correct match of site and function of nephron is **Option 3**: Proximal Convoluted Tubule (PCT) - Absorption of sodium by hydrogen bicarbonate from filtrate.

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