The Nervous System

The Nervous System

1. Sense

   • Sight
     • Smell
       • Hearing
         • Touch
           • Taste

2. Stimulus

   • Light
     • Chemicals in air
       • Vibration of air particles
         • Heat & Pressure
           • Chemicals in food

3. Preceptor

   • Eye
     • Nose
       • Ear
         • Skin
           • Tongue

4. Conscious action:We must think about it, involves the brain (Picking up a £20 note on the floor)

5. Reflex action: doesn't involve brain, only uses central nervous system (Moving hand if touched a hot plate)

   • Rapid
   • Automatic
   • Protective

6. Neurone-The pathway an impulse follows 'the nerves'

   • Receptor- What you are responding to the stimulas
     • Stimulas-What you are responding to
       • Response-The action you do
         • Effector-What brings about the response
           • Synapse-The gap between neurones

7. Stimulas (Stimulates) > Receptor (Sensory Neurone)(Electrical impulses) > Central Nervous System (Relay Neurone)(Neurotransmitter (gas) produced and diffuses across synapse)(Only important) > (Motor Neurone) Effector > Response

   • E.g Iris dilating/Contracting: Stimulus (Light) > Receptor (Eye) > Co-Ordinator (CNS) > Effector (Muscles in the iris) > Response (Iris dilating)

8. Eye: Cornea - Clear layer to protect inside of the eye

   • Lens - Focuses light onto the retina
     • Retina - Detects the light
       • Optic nerve - Connection from eye to brain
         • Sclera - Protects inside of the eye (white)
           • Iris - The muscles that control the site of the pupil to let more or less light in
             • Pupil - Entrance to the eye for light. Size is determined by the iris

9. CNS VS. NS

   • CNS
   • CNS & NS
     • Spinal Cord
       • Neurones
   • NS
     • Brain