Crash Course PNS

• Peripheral nervous system


  Keeps the brain connected to the outside world
• Without the peripheral nervous system, the brain would become isolated and start to confuse its own thoughts for actual experiences
• Peripheral nervous system


  • Provides the central nervous system with information about the physical environment
  • Allows the brain to respond to the physical environment
• Types of sensory nerve receptors

  • Thermoreceptors
  • Photoreceptors
  • Chemoreceptors
  • Mechanoreceptors
  • Nociceptors
• Nociceptors


  Nerve receptors that fire only to indicate pain
• Pain signal through the nervous system

  1. Stimulating event

  2. Reception of signal by nociceptors

  3. Transmission of signal to spinal cord and brain

  4. Interpretation of signal by brain

  5. Motor response
• Action potential


  Electrical event that sends a signal along a neuron
• Synapses


  Connections between neurons where signals are transmitted either electrically or chemically
• Reflex arc


  The five steps the nervous system goes through to produce a reflex response
• Types of reflexes


  • Innate/intrinsic reflexes
  • Learned/acquired reflexes
• Reflex arcs


  • Stimulate some muscles while inhibiting others
  • Allow for immediate reactions without conscious processing in the brain
• Muscle and tendon spindles


  Receptors that sense stretching and generate reflex arcs to contract the muscle
• Pain signal processing in the brain

  1. Thalamus receives signal

  2. Somatosensory cortex identifies and localizes the pain

  3. Limbic system registers emotional suffering

  4. Frontal cortex assigns meaning to the pain