Nervous system

• Central nervous system


  Brain and spinal cord
• Peripheral nervous system


  Somatic and autonomic
• Functional divisions of the peripheral nervous system

  • Autonomic - sympathetic and parasympathetic
  • Somatic - sensory and motor
• Structural organs of the central nervous system (CNS)

  • Brain - interprets information and decides on appropriate action, responsible for "complex" decisions
  • Spinal Cord - delicate cable of nerve fibers that stretches from the base of the brain to the lower back, connects the brain to the rest of the body, receives information from the peripheral nervous system and conveys message to brain, controls reflex action & information transmission
• Key functions of the CNS

  • To receive information (input)
  • Integrate/interpret information based on past experiences (processing)
  • Guide actions (output)
• Peripheral Nervous System (PNS)

  Consists of all neurons outside the CNS, Relay sensory information to the CNS, Carry motor information from the CNS to muscles and organs via the spinal cord
• Functions of the PNS

  • Somatic - carries out all voluntary movement that requires conscious thought
  • Autonomic - carries out automatic movement (e.g. breathing, heart beating, stomach churning)
• Autonomic Nervous System


  • Sympathetic - Prepares the body for vigorous activity, Dominant when highly aroused or when reacting to threat or danger (fight or flight response)
  • Parasympathetic - Reverses the effects of the Sympathetic NS by returning the body's internal systems to its natural level, Dominant during 'homeostasis'
• Somatic Nervous System


  • Sensory Neurons (Afferent/IN) - Transmits messages from the body and senses to the CNS via the spinal cord
  • Motor Neurons (Efferent/OUT) - Sends commands from the CNS to concerned body part (muscles, organs, glands)
• The Human Brain


  • Weighs 1300 - 1400 g, Made up of about 100 billion neurons, "the most complex living structure on the universe"
• Brain's outer appearance


  • Folds and crevices - increase the surface area of the cerebral cortex
• Top view - outer brain

  • Cerebral Cortex
  • Cerebellum
  • Brainstem
• Cerebral Cortex


  The brain's outer covering where information is stored
• White Matter


  The brain's neural pathways that connect the different parts of grey matter as well as other inner structures
• Corpus Callosum


  A thick band of fat-insulated fibers that allows the two hemispheres to communicate with each other
• Function of the Spinal Cord

  • Transmit messages from sensory neurons to the brain (afferent pathway)
  • Send messages from the brain to motor neurons for performing voluntary and involuntary responses
  • Regulate/control the reflex response
• Reflex response


  An automatic, involuntary reaction to a stimulus
• Four Lobes of the Brain

  • Frontal - higher order mental abilities like reasoning, planning, decision making, also contains the motor cortex, LEFT frontal lobe contains Broca's area that is responsible for speech & language
  • Parietal - contains the sensory cortex (primary sensory area) where bodily sensations are registered
  • Occipital - primary visual area of the cerebral cortex
  • Temporal - contain the primary auditory cortex, LEFT temporal lobe contains Wernicke's area that enables language comprehension