Question

12 which statement describes cerebrospinal fluid? multiple choice it is formed by oligodendrocytes. it maintains a stable ionic concentration in the brain and spinal cord. it reenters the blood stream via the central canal. its rate of production is high in children, dropping to lower rates in adults.

Explanation:

1. Analyze the first option: Oligodendrocytes form myelin sheaths in the central nervous system, while cerebrospinal fluid (CSF) is formed by choroid plexus epithelial cells, so this is incorrect.
2. Analyze the second option: One of the key functions of CSF is to maintain a stable ionic (and chemical) environment for the brain and spinal cord, which is a correct description.
3. Analyze the third option: CSF reenters the bloodstream via arachnoid granulations (or villi), not the central canal, so this is incorrect.
4. Analyze the fourth option: The rate of CSF production is relatively constant across different age groups (children and adults) in normal conditions, so this is incorrect.

Answer:

B. It maintains a stable ionic concentration in the brain and spinal cord.