nervous system

• The nervous system is divided into two subsystems:

  • Central nervous system (CNS)
  • Peripheral nervous system (PNS)
• The CNS is made up of the brain and the spinal cord
• The brain is the centre of all conscious awareness. The brain's outer layer, the cerebral cortex, is only 3 mm thick. It is only found in mammals.
• The brain is highly developed in humans and is what distinguishes our higher mental functions from those of other animals
• The brain is divided into two hemispheres
• The spinal cord is an extension of the brain. It passes messages to and from the brain and connects nerves to the PNS. It is also responsible for reflex actions such as pulling your hand away from a hot plate
• Peripheral nervous system (PNS) Sends information to the CNS from the outside world, and transmits messages from the CNS to muscles and glands in the body.
• The peripheral nervous system is further subdivided into the:

  • Autonomic nervous system (ANS) governs vital functions in the body such as breathing, heart rate, digestion, sexual arousal and stress responses
  • Somatic nervous system (SNS) governs muscle movement and receives information from sensory receptors
• Autonomic nervous system (ANS) Transmits information to and from internal bodily organs. It is 'autonomic' as the system operates involuntarily (i.e. automatic). It has two main divisions: the sympathetic and parasympathetic nervous systems.
• Central nervous system (CNS) Consists of the brain and the spinal cord and is the origin of all complex commands and decisions.