Which is true about the difference between cortical and juxtamedullary nephrons?

Options

A. Majority of nephrons are juxtamedullary
B. Glomeruli and loops of Henle of cortiocal nephrons lie completely in cortex
C. The afferent arterioles of the juxtamedullary nephrons give rise to most of vasarecta
D. Cortical nephrons lack vasa recta

Answer

To answer the question about the differences between cortical and juxtamedullary nephrons, we can analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Understanding Nephrons**:
- There are two main types of nephrons in the kidneys: cortical nephrons and juxtamedullary nephrons.
- Cortical nephrons are primarily located in the cortex of the kidney, while juxtamedullary nephrons are located at the junction of the cortex and medulla.

2. **Analyzing the Options**:
- **Option 1**: "Majority of nephrons are juxtamedullary."
- This statement is **false**. Approximately 80-85% of nephrons are cortical, while only 15-20% are juxtamedullary.

- **Option 2**: "Glomeruli and loops of Henle of cortical nephrons lie completely in the cortex."
- This statement is **false**. While the glomeruli of cortical nephrons are located in the cortex, the loops of Henle can extend into the medulla.

- **Option 3**: "The afferent arterioles of juxtamedullary nephrons give rise to most of the vasa recta."
- This statement is **false**. It is the efferent arterioles of juxtamedullary nephrons that give rise to the vasa recta, not the afferent arterioles.

- **Option 4**: "Cortical nephrons lack vasa recta."
- This statement is **true**. Cortical nephrons do not have vasa recta, which are associated with juxtamedullary nephrons.

3. **Conclusion**:
- Based on the analysis, the correct statement regarding the differences between cortical and juxtamedullary nephrons is **Option 4**: "Cortical nephrons lack vasa recta."

### Final Answer:
The correct option is **Option 4**: "Cortical nephrons lack vasa recta."