Biology – Nervous System

- Stimulus: Any change that produces a reaction in animals or plants.  

- Meninges: Protective membranes that cover the brain.  

- Nerves: Thread‑like structures forming a network, part of the nervous system.  

Parts of the Brain  

- Cerebrum  

  - The largest part of the brain.  

  - Contains ridges and furrows.  

  - Controls five senses: pain, temperature, sight, taste, hearing.  

- Cerebellum  

  - Egg‑shaped, located beneath the cerebrum.  

  - Helps maintain balance.  

  - Coordinates muscle movement.  

- Medulla oblongata  

  - Known as the brain stem.  

  - Connects the brain to the spinal cord.  

  - Controls involuntary actions like breathing and heartbeat.  

Protection of the Brain  

- The space between the membranes is filled with cerebrospinal fluid (CSF).  

  - Protects the brain from shocks.  

  - Nourishes the brain.  

Functions of the Nervous System  

- Reflex action: Automatic responses without involving the brain (e.g., pulling the hand away from heat).  

- Mixed nerves: Carry impulses both ways: from the brain/spinal cord to muscles/glands, and from sensory organs back to the brain.  

Neuron – Fundamental Unit of the Nervous System  

- Dendrites: Receive signals and carry them toward the cell body.  

- Cell body (Soma): Contains the nucleus, processes signals.  

- Axon: Carries signals away from the cell body to other neurons or muscles.  

Neurogenesis  

- The process of creating new neurons in the brain.