The function of cerebrospinal fluid does not include:

Options

A. Protection of brain and spinal cord by containing antibody
B. Protection of delicate brain and spinal cord from shock
C. As a medium for excretion of waste product
D. Buoyancy to brain

Answer

To determine which function is not performed by cerebrospinal fluid (CSF), we first need to understand the actual functions of CSF. Here’s a step-by-step breakdown of the solution:

### Step 1: Identify the Functions of Cerebrospinal Fluid (CSF)
CSF has several important functions, including:
- **Protection**: It acts as a cushion for the brain and spinal cord, protecting them from trauma and shock.
- **Nutrient Supply**: CSF supplies essential nutrients to the nervous system tissues.
- **Waste Removal**: It helps in removing waste products from cerebral metabolism.
- **Buoyancy**: CSF provides buoyancy to the brain, reducing its effective weight and preventing damage from its own weight.

### Step 2: Analyze the Options Given
Now, let’s analyze the options provided in the question:
1. Protects the brain and spinal cord from antibodies.
2. Delicate brain and spinal cord are protected from shock and trauma.
3. It is a medium for excretion of waste products.
4. Provides buoyancy to the brain.

### Step 3: Determine Which Option is Incorrect
- **Option 1** states that CSF protects the brain and spinal cord from antibodies. This is not a function of CSF. CSF does not contain antibodies that would provide protection; instead, it serves to cushion and support the brain and spinal cord.
- **Option 2** correctly states that CSF protects the brain and spinal cord from shock and trauma.
- **Option 3** correctly identifies CSF as a medium for excretion of waste products.
- **Option 4** correctly states that CSF provides buoyancy to the brain.

### Conclusion
Based on the analysis, the function that cerebrospinal fluid does not include is:
**Option 1: Protects the brain and spinal cord from antibodies.**