Write a note on meninges of central nervous system in human being.(b) Give functions of cerebrospinal fluid.

Answer:

(a) Meninges: The brain and spinal cord are covered by three protective connective-tissue membranes:

1. Dura mater: the outermost, tough, thick fibrous layer lying against the cranium and vertebral canal.
2. Arachnoid mater: the middle, thin, web-like layer; the space between it and the dura mater is the subdural space.
3. Pia mater: the innermost, thin, highly vascular layer closely attached to the brain and spinal cord. The subarachnoid space between arachnoid and pia mater is filled with cerebrospinal fluid.

Inflammation of the meninges is called meningitis.

(b) Functions of cerebrospinal fluid (CSF):

• Acts as a shock absorber and protects the brain and spinal cord from mechanical injury.
• Keeps the brain buoyant and moist.
• Supplies nutrients and oxygen to nervous tissue and removes wastes.
• Maintains a constant pressure around the CNS.