the nervous system

• what is the nervous system and what does it do?

  • it is very complex and not fully understood
  • it is the body’s command center
  • it has taken 700 million years to develop
  • it generates and controls behavior
  • it sends and receives messages between your brain and body and adapts your response to any situation
• components

  • central nervous system (CNS):
  • brain 
  • spinal cord
  • within the skull and vertebral column
  • peripheral nervous system (PNS):
  • nerves
  • connects the CNS to the other tissues of the body
• the brain

  • 1.5kg
  • made up of about 100 billion neurons
  • sits entirely within the skull
  • two main hemispheres
  • left-hand side of the brain controls the right-hand side of the body and visa versa
  • integrates all the incoming information and then ensures an appropriate response
  • four lobes: occipital, temporal frontal, parietal
• the spinal cord

  • thick cord of neurons that descends from the brain to the bottom of the spine - about 45cm
  • at its widest about the same diameter as your thumb
  • carries information away from and towards your brain
  • connects to the brain at the brainstem 
  • connects to the PNS via the spinal nerves
• PNS

  • all the nerves that come of the CNS and then disseminate to the rest of the body
  • some carry information towards the brain others carry information away from the brain
  • 12 pairs of cranial nerves
  • control function of the face and special senses
  • arise from brainstem
  • 31 pairs of spinal nerves
  • control functions of head, neck, arms, legs, thorax and internal organs
  • arise from spinal cord
  • spinal nerves branch out to become the nerve that run up and down your arms and legs
• nerve endings

  • nerves communicate with tissues via specialist receptors and end organs:
  • motor end plate to make muscles work 
  • sensory receptors so that we can feel
  • internal organs (e.g. peristalsis)
• the neuron

  • the CNS and PNS is made up of specialist cells called a neuron
  • a single neuron is very small
  • a bundle of neurons together in the PNS make a nerve
• how does the brain communicate with the body?

  • predominantly using electrical impulses called action potentials that run along the neurons
  • but it also uses chemicals too – mainly at the point where one nerve meets another nerve
• what is the area where one neuron meets another to pass on key information called?

  synapse
• what is the name of the chemicals that pass the message from one neuron to the next?

  neurotransmitters e.g. dopamine, serotonin, acetylcholine, substance P, glutamate, GABA, histamine, endorphins, adrenaline, etc
• functions of the nervous system

  movement, sensation, thoughts, memory, learning, feelings, balance, coordination, emotions, behavior, perception, puberty, aging, vision, hearing, taste/smell, vestibular function, sleep, healing and your immune system, breathing, heart rate, micturition, digestion, defecation, sweating, blushing, goosebumps, hormone control and release, and language
• signs of neurological injury or illness

  • weakness 
  • sensory loss/changes
  • reduced coordination
  • reduced proprioception
  • altered balance
  • visual field loss
  • hearing impairment
  • altered speech
  • unable to swallow
• symptoms of neurological injury or illness

  • double vision
  • hearing loss
  • pins and needles
  • numbness
  • pain (not always)
  • weakness
  • memory problems
  • odd behavior
  • mood changes
• peripheral nerve disorders


  carpal tunnel syndrome, sciatica, trauma, erb’s palsy, neuropathy, guillain barre syndrome, MND
• central nervous system disorders


  stroke, head injury, meningitis, cerebral palsy, MND