Which of the following is not a function performed by glial cells ?

Options

A. Remove cellular debris produced by damaged or dying cells
B. Increase the speed of electrical impulses passed down an axon
C. Form the blood - brain barrier
D. Detect internal body conditions

Answer

To determine which of the following options is not a function performed by glial cells, we need to analyze each option carefully. Glial cells, also known as neuroglia, are non-neuronal cells in the central nervous system that perform various supportive functions.

### Step-by-Step Solution:

1. **Understanding Glial Cells**:
- Glial cells support and protect neurons in the central nervous system. They play various roles, including maintaining homeostasis, forming myelin, and providing support and protection for neurons.

2. **Analyzing Option 1**:
- **Remove cellular debris produced by damaged or dying cells**: This is a function of microglial cells, which act as the immune defense in the central nervous system. They remove waste and debris, so this option is a function of glial cells.

3. **Analyzing Option 2**:
- **Increase the speed of electric impulses passed down the axon**: This function is performed by oligodendrocytes, which form the myelin sheath around axons. The myelin sheath increases the speed of electrical impulses, so this option is also a function of glial cells.

4. **Analyzing Option 3**:
- **Form a blood-brain barrier**: Astrocytes, a type of glial cell, contribute to the formation of the blood-brain barrier, which protects the brain from harmful substances in the bloodstream. Therefore, this option is also a function of glial cells.

5. **Analyzing Option 4**:
- **Detect internal body conditions**: This function is primarily associated with neurons, which are responsible for sensing and processing information about internal and external environments. Glial cells do not perform this function.

6. **Conclusion**:
- Based on the analysis, the correct answer is **Option 4: Detect internal body condition**, as this is not a function performed by glial cells.

### Final Answer:
**Option 4: Detect internal body condition** is not a function performed by glial cells.

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