Which of the following statements is not correct for most common type of nephrons of human kidney ?

Options

A. They are small size, less coiled with major part present at the junction of cortex and medulla.
B. They have short length of loop of Henle.
C. They do not have major role to from counter current mechanism.
D. They have no or highly reduced vasa recta.

Answer

To determine which statement is not correct regarding the most common type of nephrons in the human kidney, we need to analyze the characteristics of cortical nephrons. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Types of Nephrons
- The human kidney contains two types of nephrons: **cortical nephrons** and **juxtamedullary nephrons**.
- Cortical nephrons are the most common type and are primarily located in the cortex of the kidney.

**Hint:** Remember the two types of nephrons and where they are located in the kidney.

### Step 2: Characteristics of Cortical Nephrons
- **Loop of Henle**: In cortical nephrons, the loop of Henle is relatively short compared to juxtamedullary nephrons, which have a long loop of Henle.
- **Vasa Recta**: Cortical nephrons have either no or highly reduced vasa recta (the straight capillaries that accompany the loop of Henle).
- **Location**: The major part of cortical nephrons is located in the cortex, not at the junction of the cortex and medulla.

**Hint:** Focus on the structure and function of the loop of Henle and vasa recta in cortical nephrons.

### Step 3: Evaluate Each Statement
1. **Statement 1**: "They are small size less coiled with major part present at the junction of cortex and medulla."
- This statement is **incorrect** because cortical nephrons are not primarily located at the junction; they are mainly found in the cortex, and they are not small in size.

2. **Statement 2**: "They have short length of loop of Henle."
- This statement is **correct**; cortical nephrons do have a short loop of Henle.

3. **Statement 3**: "They do not have major role to form counter current mechanism."
- This statement is **correct**; due to their short loop of Henle, they do not significantly contribute to the countercurrent mechanism.

4. **Statement 4**: "They have no or highly reduced Vasa recta."
- This statement is **correct**; cortical nephrons have reduced or absent vasa recta.

### Step 4: Conclusion
- The only statement that is not correct for cortical nephrons is **Statement 1**. Therefore, the answer to the question is **Statement 1**.

**Final Answer:** Statement 1 is not correct for most common type of nephrons of the human kidney.