Neurophys

• What are the basic functions of the nervous system?

  Detection of stimuli, processing information, and transmission of decisions to effectors
• How does the nervous system transmit information to the CNS?

  Via afferent (ascending) sensory neurons

  
• What is the role of interneurons in the nervous system?

  Processing information and decision making

  
• What do efferent neurons do?

  Transmit decisions to effectors
• What is the sequence of electrical signals in neurons?

  Graded potentials -> Trigger zone -> Action potentials -> Propagation

  
• Where is the Ascending Reticular Activating Formation (ARAS) located?

  Within the thalamus

  
• What is the function of the ARAS?

  Receives input from all sensory systems and filters information

  
• What happens if there is a lesion in the ARAS?

  It can result in a coma, with the cortex not awake

  
• What type of root is the dorsal root of the spinal cord?

  Sensory
• What type of root is the ventral root of the spinal cord?

  Motor
• What is the spinal nerve classified as?

  Mixed
• What spinal cord segments are connected to every forelimb and hind limb nerve?

  2 to 5 spinal cord segments
• What spinal segments are associated with the lumbosacral plexus?

  L4-S2

  
• What spinal segments are associated with the brachial plexus?

  C6-T2

  
• What is the role of the first-order sensory neuron?

  To detect stimuli via sensory receptors
• How do sensory receptors transduce stimuli?

  By responding to one type of energy per neuron
• What type of energy do mechanoreceptors respond to?

  Mechanical energy (stretch)
• What type of energy do chemoreceptors respond to?

  Chemical energy (ligand binding)
• What type of energy do thermoreceptors respond to?

  Thermal energy
• What is the process of signal transduction in mechanoreceptors?

  Stimulus of channel -> Ionic flow -> Depolarization -> Graded Potential
• Where are the cell bodies of first-order sensory neurons located?

  In the dorsal gray horn for sensory neurons
• What happens to the signal received from the first-order neuron?

  It is transmitted to the second-order neurons via synaptic transmission
• Where do second-order neurons enter after receiving signals?

  They enter the white matter and ascend in tracts
• What is the location of the cell bodies for second-order neurons?

  In the thalamus/ARAS
• What do third-order neurons do?

  Project onto the somatosensory cortex for signal processing
• What is adaptation in sensory receptors?

  It is when the signal strength declines over time
• What is the pathway for sensory signals from the periphery to the cortex?

  1st order neuron -> spinal nerve -> 2nd order neuron in DGH -> spinal tract -> 3rd order neuron in ARAS -> cortex
• How do CN 1 and CN 2 differ from other cranial nerves in their pathway?

  They do not go to the brainstem but to their receptive brain regions
• What is the function of the sensory cortex?

  Perception of sensory information
• What is the localization principle in the sensory cortex?

  Every 3rd order neuron terminates in a designated location of the cortex
• What is the significance of the cortical map?

  It shows point-to-point mapping of body parts to specific cortex locations
• What is the somato-sensory map or homunculus?

  It represents the disproportionate representation of body parts with more sensory receptors
• How is pain defined?

  As an unpleasant sensory and emotional experience associated with tissue damage
• What is nociceptor stimulation?

  It is the transduction of pain stimuli via ionic channel stimulation

  
• What is the difference between first and second pain?

  First pain is sharp and localized, while second pain is dull and diffuse
• What triggers first pain?

  Initial mechanical force of injury or excess heat/cold
• What fibers are associated with first pain?

  A delta fibers
• What neurotransmitter is released during first pain?

  Glutamate
• What triggers second pain?

  Tissue damage leading to the release of intracellular chemicals
• What fibers are associated with second pain?

  C fibers