Nervous system

• The nervous system consists of the central nervous system and the peripheral nervous system.
• The CNS consists of the brain and spinal cord and is the origin for all complex demands/decisions.
• The PNS sends info (sensory (afferent) neurons) to the CNS from the outside world, and transmits messages (motor (efferent) neurons) from the CNS that directs muscles to act.
• The autonomic nervous system (Division of PNS): transmits info to and from internal bodily organs (breathing, heart rate, sexual arousal and stress response). It operates involuntarily and has 2 main divisions: the sympathetic (arousal) and the parasympathetic(rest and digest).
• The main 2 functions of the NS, which is our primary internal communication system are:

  1. Collect, process and to respond to info in the environment
  2. Coordinate the working of different organs and cells in the body
• The brain is the centre of all conscious awareness. It's outer layer the cerebral cortex, is highly developed in humans. It also carries out most unconscious processes.
• The spinal cord is an extension of the brain and is responsible for reflex actions (pulling your hand away from a hot plate). It passes messages to and from the brain and connects nerves to the PNS.
• Somatic nervous system (division of PNS): The part of the nervous system that controls voluntary muscles and receives information from sensory receptors.
• Differences from the SNS and the ANS:

  1. SNS has sensory/motor pathways while ANS is purely motor
  2. SNS controls skeletal muscles and movement while ANS controls internal organs and glands
  3. SNS includes all of voluntary functions while ANS includes all of involuntary functions
• Homeostasis is the regulation of the internal environment through balance between the ANS and PNS.
• The Human Nervous System is a body wide system of nerve cells that collects info from the world, processes and then takes action by directing bodily organs and muscles via transmission of electro chemical messages.
• Sympathetic division system increases bodily activities. Releases noradrenaline. Activates in stress response (fight or flight):

  • HR increases
  • Sweat increases
  • Breathing rate increases
  • Dilates pupils
  • Inhibits digestion
• Parasympathetic division system decreases bodily activities. Releases acetylcholine. Activates in rest:

  • HR decreases
  • Sweat decreases
  • Breathing rate decreases
  • Constricts pupils
  • Stimulates digestion