The Systems

• Nervous System


  • Central nervous system
  • Peripheral nervous system
• Central nervous system


  Brain & spinal cord, processes incoming messages and initiates outgoing messages
• Peripheral nervous system


  Composed of nerves outside the brain and spinal cord, connects CNS to the rest of the body, relays messages to and from the CNS to the rest of the body (receptors/glands/organs/muscles)
• Divisions of the PNS

  • Afferent Division (Sensory)
  • Efferent Division (Motor)
• Afferent Division (Sensory)


  Also known as the sensory division - has fibres that carry impulses into the CNS from receptors in the skin, muscles & joints, can be further divided into Somatic sensory neurons (impulses from the skin and muscles) and Visceral sensory neurons (impulses from internal organs)
• Efferent Division (Motor)


  Also known as the motor division - has fibres that carry impulses away from the CNS, can be further divided into Somatic division (impulses from the CNS to skeletal muscle) and Autonomic division (impulses from the CNS to heart muscle, involuntary muscles & glands, further divided into Sympathetic and Parasympathetic)
• Autonomic Nervous System


  • Controls the body's internal environment - involuntary activities of smooth muscles & glands, effect can be excitation or inhibition, operates without conscious control - regulated by cells in the medulla, hypothalamus & cerebral cortex, Sympathetic response system that prepares person for action if threat is present, activates fight/flight response, Parasympathetic maintains day-to-day function of the body, returns body to its normal state (rest and digest)