The Nervous System

• What does multicellular organisms develop?

  Nervous and hormonal communication systems
• What is nervous system made up of?

  • Central Nervous System - brain and spinal cord only
  • Sensory neourons - carry information as electrical impilses from the receptors to the CNS
  • Motor neurons - carry electrical impulsed from CNS to effectors
  • Effectors - all muscles and glands, which respond to nervous system
• What do receptors do?


  The cells that detect stimuli
• What do effectors do?


  Respond to nervous impulses and bring about a change
• What`s the difference between muscles and glands as effectors?


  Muscles contract in response to a nervous impulse, whereas glands secrete hormones
• What is a synapse?


  The connection between two neurons
• How does nerve signal is transferred?


  Neurotransmitters( chemicals) which diffuse across the gap
• What do these chemicals do?


  Set off a new lectrical signal in the next neurone
• What passes along nerve cells?

  Electrical impulse
• What is the role of a relay neurone?

  To transfer a signal from a sensory neurone to a motor neurone
• What is a reflex?

  An automatic response to a stimulus
• Why are reflexes important? 

  They protect us from harm