The Nervous System

The Nervous System

1. You have five sense organs.

   • They all contain different RECEPTORS-groups of cells which are sensitive to specific stimuli.
     • A STIMULUS can be anything from
       • Light
       • Sound
       • Pressure
       • Chemical
       • Change in position or temperature.
     • RECEPTORS work by changing stimulus energy to electric impulses.

2. The five sense organs and the receptors they contain.

   • Eyes-Light receptors
   • Ears-Sound and Balance receptors.
   • Nose-Smell receptors-sensitive to chemical stimuli.
   • Tongue-taste receptors for bitter, salt, sweet, sour plus savoury eg Monosodium Glutamate.
   • Skin-sensitive to touch, pressure and temperature change.

3. The Central Nervous system

   • Consists of Brain and spinal cord ONLY.
   • Where all information from organs is sent & where reflexes and actions are co-ordinated.
   • Neurones (nerve cells)
     • Transmit the information (as electric impulses) very quickly to and from the CNS.
     • Sensory Neurones-The nerve cells that carry signals as electrical impulses from the receptors in sense organs to CNS
     • Motor Neurones: Nerve cells that carry signals to the effector muscles or glands.