Nervous System

• The central nervous system consists of the brain and spinal cord
• The nervous system enables humans to react to their surroundings and to coordinate their behaviour
• Information from receptors passes along neurones as electrical impulses to the central nervous system
• The central nervous system coordinates the response of effectors which may be muscles contracting or glands secreting hormones
• stimulus - receptor - coordinator - effector - response
• Reflex actions are automatic and rapid; they do not involve the conscious part of the brain
• Sensory neurons carry information as electrical impulses from the receptors to the central nervous system
• Motor neurons carry electrical impulses from the central nervous system to effectors
• Effectors are muscles and glands which respond to nervous impulses
• The connection between two neurons is a synapse
• Electrical signals are transferred between neutrons by chemicals which diffuse across the synapse sending a new electrical signal to the next neurone
• Neurones in a reflex action go through the spinal cord
• Relay neurones send an electrical impulse from a sensory neuron to a motor neuron via a synapse
• Reaction time practical

  • The person will sit with their arm resting on the edge of the table
  • Hold a ruler between their thumb and forefinger and let go with no warning
  • The person will catch the ruler as soon as they can
  • Then repeat the experiment 5 minutes after the person has had a caffeinated drink
• Reaction time is more accurately measured with a computer because it removes human error from the measurement and can record the reaction time in more accurate measurements