nervous system & reflex arc

• Nerve cell


  Also called a neuron
• Nerve cell


  • Long
  • Thin
  • Lots of branch connections to either end
  • Adapted to carry electrical impulses from one point to another
• Synapse


  Connection between nerve cells where electrical impulses are converted to chemical signals to pass between cells
• Nerve cell communication


  1. Electrical impulse hits end of nerve

  2. Causes release of chemicals

  3. Chemicals diffuse across gap to next nerve cell

  4. Triggers another electrical impulse

  5. Electrical impulse continues along new neuron
• Central nervous system


  • Made up of brain and spinal cord
  • Where 'thinking' takes place
  • Takes in sensory information
  • Decides what needs to be done
  • Sends out orders to the rest of the body
• Sensory neurons


  Carry information from receptors all over the body to the central nervous system
• Motor neurons


  Carry impulses from the central nervous system to effectors (muscles or glands)
• Reflex arc


  • Nerve pathway that underlies unconscious reflexes
  • Rapid and automatic response to stimuli
• Reflex arc example

  1. Pressure of sharp object detected by receptor cells in skin

  2. Sensory neuron carries impulse to spinal cord

  3. Relay neuron transfers impulse to motor neuron

  4. Motor neuron carries impulse to effector (bicep) to move hand away