The Nervous System

• The Nervous System:

  • The nervous system is a specialised network of cells in the human body and is the primary internal communication system.
  • Based on electrical and chemical signals whilst the endocrine system is based on hormones.
• The Nervous System:

  • Central nervous system (CNS).
  • Peripheral nervous system (PNS).
• Central Nervous System (CNS):

  • Made up of the brain and spinal cord.
• Central Nervous System (CNS):

  Brain

  • Brain is the centre of all conscious awareness.
  • The outer layer (cerebral cortex) in only 3mm thick and covers the brain like an orange peel - only found in mammals.
  • Highly developed in humans and is what distinguishes our higher mental functions. Only a few living creatures don’t have a brain.
• Central Nervous System (CNS):

  Spinal Cord

  • Spinal cord is an extension of the brain and passes messages to and from the brain and connects nerves to the PNS. Also responsible for reflex actions e.g pulling your hand away from a hot plate.
• Peripheral Nervous System (PNS):

  • Transmits messages via millions of neuron’s (nerve cells) to and from the central nervous system.
• Peripheral Nervous System (PNS):

  • Divided into: autonomic nervous system and the somatic nervous system.
• Peripheral Nervous System (PNS):

  Autonomic nervous system (ANS)

  • Governs vital functions in the body like breathing, heart rate, digestion, sexual arousal and stress responses.
• Peripheral Nervous System (PNS):

  Somatic nervous system (SNS)

  • Governs muscle movement and receives information from sensory receptors.