Function (somatic) NS

• What is proprioception?

  The sensation of body position
• What are the classifications of sensory receptors?

  • Mechanoreceptors: touch, pressure, proprioception, hearing, balance
  • Chemoreceptors: smell and taste
  • Thermoreceptors: respond to temperature changes
  • Photoreceptors: vision
  • Nociceptors: pain from extreme stimuli

  
• What do mechanoreceptors respond to?

  Compression, bending, stretching of cells
• What do chemoreceptors detect?

  Chemicals attaching to receptors
• What is the function of thermoreceptors?

  Respond to changes in temperature
• What do photoreceptors respond to?

  Light for vision
• What do nociceptors detect?

  Extreme mechanical, chemical, or thermal stimuli
• Where are cutaneous receptors located?

  • Associated with the skin
• Where are visceroreceptors located?

  • Associated with organs
• Where are proprioceptors located?

  • Associated with joints and tendons
• What are free nerve endings?

  Simple sensory receptors scattered throughout the body
• What is the primary function of cold receptors?

  Detect cold temperatures
• How do Merkel disks function?

  Detect light touch and superficial pressure
• What do hair follicle receptors respond to?

  Slight bending of hair during light touch
• What is the function of Pacinian corpuscles?

  Detect deep cutaneous pressure and vibration

  
• Where are Meissner corpuscles distributed?

  Throughout dermal papillae
• What do Ruffini end organs respond to?

  Continuous touch or pressure
• What happens when a sensory receptor is stimulated?

  1. Generates a graded receptor potential
  2. If large enough, triggers an action potential
  3. Action potential travels to the CNS

  
• What is the difference between primary and secondary receptors?

  • Primary Receptors: Most common
  • Secondary Receptors: Sight, smell, taste, balance

  
• What is the process when a mechanoreceptor is stimulated?

  1. Pressure stimulus applied
  2. Generates a graded potential
  3. Reaches threshold, generates action potentials
  4. Propagated towards the CNS

  
• What occurs when a chemoreceptor is stimulated by saltiness?

  1. Generates a receptor potential
  2. Releases neurotransmitter into synaptic cleft
  3. Stimulates sensory neuron
  4. Generates action potentials towards the CNS
• What is the spinothalamic tract responsible for?

  • Pain, touch, pressure, itch, and tickle sensations
  • Major pathway for conscious perception of external stimuli

  
• What is the dorsal-column tract responsible for?

  • Proprioception, two-point determination, pressure
  • Different tracts for superior and inferior body parts

  
• What does the spinocerebellar tract do?

  • Responsible for proprioception in upper thoracic, lumbar, and lower limbs
  • Different tracts for anterior and posterior body regions

  
• How does the cerebral cortex modify sensations?

  • Reduces conscious perception
  • Passes down from brain to spinal cord
• What are neuromodulators?

  • Decrease frequency of action potentials
  • Examples: endorphins, enkephalins
• What are the two components of pain perception?

  Rapid and slowly propagated action potentials
• What is referred pain?

  Pain sensation in a different body area
• What is the primary somatosensory cortex responsible for?

  • Size reflective of number of neurons
  • Associated with sensory processing
• What is the primary motor cortex responsible for?

  • Responsible for voluntary movements
  • Involuntary functions are reflexes

  
• What are upper motor neurons?

  • Connect cerebral cortex to lower motor neurons
  • Can connect directly or through interneurons

  
• What are lower motor neurons?

  • Connect upper motor neurons to skeletal muscles
  • Axons extend from CNS into PNS

  
• What are the steps for voluntary movement?

  1. Cerebral cortex communicates with basal nuclei and cerebellum
  2. Upper motor neurons stimulated
  3. Lower motor neurons innervate skeletal muscles

  
• What do direct pathways control?

  • Speed and precision of movements
  • Includes corticospinal and corticobulbar tracts

  
• What do indirect pathways control?

  • Less precise movements of trunk and limbs
  • Synapse in intermediate nucleus

  
• What is the function of the rubrospinal tract?

  • Regulates fine motor control of upper limb muscles
• What is the function of the vestibulospinal tract?

  • Innervates extensor muscles for posture
• What is the function of the reticulospinal tract?

  • Maintains posture and balance
• What is the role of basal nuclei?

  • Planning, organizing, coordinating movements
  • Feedback loops with thalamus and cerebral cortex
• What is the role of the cerebellum?

  • Maintains muscle tone and balance
  • Coordinates eye movements and fine movements