The divisions of the nervous system

• The nervous system

  Biological psychologists assume behaviour and experiences are caused by activity in the nervous system. The nervous system is a specialised network of cells in the human body and is our primary internal communication system. It has two main functions: to collect, process and respond to information in the environment / to coordinate the working of different organs and cells.
• Human nervous system -> Central nervous system (CNS) / Peripheral nervous system (PNS)

  CNS -> Brain / Spinal cord

  PNS -> Automatic nervous system / Somatic nervous system

  ANS -> Sympathetic nervous system / Parasympathetic nervous system
• The central nervous system

  The brain is the centre of all conscious awareness. The brain’s outer layer, the cerebral cortex, is highly developed in human. The brain is divided into two hemispheres. The spinal cord is an extension of the brain. It is responsible for reflex actions. The CNS passes messages to and from the brain and connects nerves to the PNS.
• The peripheral nervous system

  The PNS transmits messages via millions of neurons (nerve cells), to and from the central nervous system. The PNS is further subdivided into: the autonomic nervous system (ANS), the somatic nervous system (SNS).
• The somatic nervous system

  This is the part of the PNS that is responsible for carrying sensory and motor information to and from the spinal cord. The somatic nervous system is made up of 12 pairs of cranial nerves from the brain, 31 pairs of spinal nerves from the spinal cord and all of their branches.
• The autonomic nervous system

  This governs vital functions in the body such as breathing, heart rate, digestion, sexual arousal and stress responses. The two main divisions of the autonomic nervous system are: the sympathetic nervous system / the parasympathetic nervous system. Their actions are mostly antagonistic meaning they usefully work in opposition to each other. Parasympathetic - generally conserves and maintains body energy and functions. Sympathetic - generally prepares the body to expend the energy for fight or flight.
• Sympathetic

  Gut - inhibits digestion / Salivary glands - inhibits salivary production / Heart - increases heart rate / Liver - stimulates glucose production / Bladder - stimulates urination / Eye - dilates pupils / Lungs - dilates bronchi


  Parasympathetic

  Gut - stimulates digestion / Salivary glands - stimulates salivary production / Heart - decreases heart rate / Liver - stimulates bile production / Bladder - inhibits urination / Eye - constricts pupils / Lungs - constricts bronchi