6.1.1 The Nervous System - Central and Peripheral

• The nervous system is divided into two parts;
  • The Central Nervous System (CNS)
  • The Peripheral Nervous System (PNS)
• These systems are clearly connected and work together so the whole system functions effectively
• The CNS is made up of the brain and the spinal cord
• The brain is central to maintaining life and has many functions including:
  • Basic functions such as regulating body temperature, heart rate and breathing 
  • Language (production and understanding)
  • Co-ordinating movement
  • Coding sensory data from the sensory organs
  • Problem-solving and planning
• The Spinal Cord ensures that signals from the brain are transmitted to the rest of the body via the PNS

The Peripheral Nervous System (PNS)

• The PNS transmits messages throughout the whole body from the brain and also relays messages back to the brain
• The PNS is divided into two sections:  
  • The Somatic Nervous System
  • The Autonomic Nervous System
• The Somatic Nervous System transmits and receives messages from the senses:
  • An example of this would be visual information from the eyes or touch information from the skin
  • It then directs the muscles to move appropriately
  • For example: If your eyes are registering that there is a car coming toward you, the Somatic System would be telling your muscles to move and to get you  out of the way

• The Autonomic NervousSystem transmits and receives information from the organs
• The ANS is divided into two further sections:
  • The Sympathetic Nervous System
  • The Parasympathetic Nervous System
• The Sympathetic System is associated with the 'fight or flight' response:
  • It prepares the body for physical activity e.g. running away or fighting
  • It is utilised when the body is in an 'alert' state e.g. when crossing the road
  • It can accelerate heart rate, widen bronchial passages for increased breathing capacity (needed when running), decrease activity of the large intestine (no time for the toilet when you're in danger!), constrict blood vessels, cause pupil dilation, activate goose bumps, start sweating and raise blood pressure
• The Parasympathetic System is popularly known as the 'rest and digest' system:
  • It helps to conserve the body's activity levels and energy by decreasing activity to be used later
  • It regulates bodily functions like digestion and urination
  • It slows heart and breathing rates, lowers blood pressure as the body enters a state of relaxation
  • Relaxation enables the body to go into 'standby' (recovery mode): the more time spent in a PNS state, the healthier a person will be

Divisions of the Nervous System