The central nervous system, or CNS, is really important for how our bodies work. Let’s break it down into three main parts:

1. Brain:

   • The brain has around 86 billion tiny cells called neurons.
   • It is split into three big areas: the cerebrum, the cerebellum, and the brainstem.

2. Spinal Cord:

   • The spinal cord is about 45 centimeters long in adults.
   • It has 31 pairs of nerves that carry messages to and from the body.

3. CNS Protection:

   • The CNS is protected by three layers called meninges:
     • The outer layer is called the dura mater.
     • The middle layer is the arachnoid mater.
     • The inner layer is the pia mater.
   • There is also a special fluid called cerebrospinal fluid (CSF) around the CNS.
     • This fluid, about 150 milliliters in total, acts like a cushion to keep our brain and spinal cord safe.

In short, the CNS helps us understand what we sense around us and controls our movements. This is super important for staying alive and healthy!