T3.4 central nervous system

• Central nervous system


  • Comprised by brain and spinal cord, encased by bones of skull and vertebral column
  • Meninges and cerebrospinal fluid (CSF) protect brain and spinal cord
  • Blood-brain barrier act as additional protector of brain
  • Responsible for integrating, processing and coordination sensory data and motor commands
  • Communicates with rest of body via peripheral nervous system
• Gray matter


  Site of integration and processing
• White matter


  Highways for signal to travel down
• Main parts of the brain

  • Cerebrum
  • Diencephalon
  • Brainstem (includes medulla, pons and midbrain)
  • Cerebellum
• Cerebrum


  • Made up of two hemispheres
  • Most superficial known as cortex and is gray matter
  • Cortex - main site of information processing and understanding
• Lobes of the cerebrum

  • Frontal lobe
  • Parietal lobe
  • Temporal lobe
  • Occipital lobe
  • Insula
• Frontal lobe


  • Important for voluntary movement, higher level executive functions
• Parietal lobe


  • Important for processing somatosensory (sensory input) information
• Temporal lobe


  • Important for receiving and interpreting sound and language
• Occipital lobe


  • Important for receiving and interpreting visual information
• Insula


  • Important for receiving and interpreting taste (gustatory) and sensory information from our organs
• Basal nuclei


  • Involved in motor control, initiate and fine tune motor skills, when dysfunction result in visible conditions e.g. Parkinson's disease and Huntington's disease
• Diencephalon


  • Deeper structures of brain that are important in maintaining homeostasis. Help regulate unconscious control of bodily function (temp, fluid balance, sleep/wake cycles). Include thalamus, hypothalamus and epithalamus
• Brainstem


  • Sits below cerebrum and above spinal cord. Maintains breathing rate and depth, heart rate and rhythm, coughing, vision, reflexes, swallowing
• Parts of the brainstem

  • Midbrain
  • Pons
  • Medulla oblongata
• Midbrain


  • Helps control subconscious/ automatic muscle activity; coordinates automatic eye movements with visual/auditory stimuli; coordinates automatic head movements with auditory stimuli. Visual/ auditory reflex
• Pons


  • Functional link between cerebrum and cerebellum; contains part of the respiratory (pneumotaxic) centre
• Medulla oblongata


  • Continuation of spinal cord; contains cardiovascular and respiratory centres also reflex centres for coughing, sneezing and swallowing
• Protective mechanisms for the brain

  • Meninges - layers of tissue surrounding the brain itself (pia mater, arachnoid mater and dura mater)
  • Blood brain barrier (BBB) - a physical barrier that limits the movement of substances from our systemic circulation into the cerebral circulation
  • Cerebral spinal fluid (CSF) - a fluid produced in the brain that continually circulate around the brain and spinal cord to deliver nutrients and remove waste
• Spinal cord


  • Extension of brain from medulla oblangata of brain through to inferior border of L1 vertebra and protected by relatively longer vertebral column and spinal cord meninges
  • Spinal nerves extend from spinal cord to innervate various muscles and glands throughout body
  • Function as a pathway for sensory and motor signals to flow and from the brain
  • Initiate spinal reflexes which are rapid reactions to stimulus mediated by spinal cord, rather than the brain
• Sensory pathways


  Info about our internal or external environment need to travel to our brain if want to become aware of it. e.g. fine touch, proprioception, pain, temperature
• Fine touch and proprioception

  Travel via same pathway called dorsal column medial lemniscus pathway. Use three-neuron system
• Motor pathways


  1. Conscious movement of our limbs begins in our primary motor cortex within our frontal lobe

  2. Help of basal nuclei and cerebellum send motor signal down spinal cord where it will exit and travel via peripheral nerves to muscle/s that we want to move

  3. Motor neurons involved, two-way neuron system comprised of upper motor neuron and lower motor neuron