The Nervous System

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The Nervous System
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The nervous system is made up of the
central nervous system (CNS) and the
peripheral nervous system.
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Nervous system- sense organs
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The Nervous System

• We have 5 sense organs that help us detect our
  surroundings
• Ears- Sound and balance
• Nose- Chemicals (smell)
• Tongue- Chemicals (taste)
• Skin- Touch, heat, pressure
• Eyes- Light

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The Nervous System
The NERVOUS SYSTEM consists mainly of the brain,
the spinal cord, nerve cells (neurones) and
receptors. CNS Central Nervous System is made up
of the brain and spinal cord.

• Types of receptor
• Light receptors in the eyes
• Sound receptors in the ears
• Chemical receptors on the tongue and in the nose
• Touch, pressure and temperature receptors in the
  skin
• Changes of position receptors in the ears
  (balance)

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Examples of reactions
Stimulus Receptor (i.e. the thing that detects the stimulus) Effector (i.e. the thing that will do the reaction) Response (i.e. action taken)
Bright light Eye Pupil Pupil constrict
Sour taste Taste bud Salivary Gland Produce saliva
Losing balance Ear Muscles Movement (stop you falling down)
Sit on a drawing pin Touch receptors Muscles Movement
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Structure of a motor neurone. The nerve impulse
is carried along the nerve fibre.
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Extension
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A reflex arc
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The impulse goes from receptor to CNS and then to
effector to bring about the response. The relay
neurone (purple) inside the spinal cord
coordinates the response by connecting the
sensory neurone to an appropriate motor neurone
(green). The information travels from one neurone
to another across a small gap called a synapse.