bio 11

  1. 4 types of receptors
    -"free-nerve endings

    - pacinian


  2. (types of receptor) Free nerve endings
    feels temperature and pain
  3. (types of receptor) Pacinian (3)
    -respond to displacement of the skin (pressure)

    -rapidly adapting

    - best suited for sensing  sudden change
  4. (types of receptor) Ruffini (2)
    -adapt slowly

    -best suited to signal gradual changes in skin stretch
  5. (types of receptor) Merkel
    -adapt slowly

    -best suited to signal gradual changes in skin indentation
  6. Topography (3)
    -orderly entry of dermatomes into the spinal cord

    -info from legs is maintain at a lower level

    -topography is maintained all way to the cortex
  7. (important features of pathway) steps from skin to brain
    • 1. info enters via dorsal root ganglion
    • 2. info projects to and synapses on to cells of dorsal column nuclei
    • 3. Contralateral projection to ventral posterior nucleus of thalamus
    • 4. primary somatosensory cortex
  8. (thalamus) Vision
    lateral geniculate nucleus
  9. (thalamus) Audition
    medial geniculate nucleus
  10. (thalamus) Gustation
    ventral posterior medial nucleus
  11. (thalamus) Somatosensation
    ventral posterior nucleus
  12. Homunculus
    "little man" on sensory map
  13. dorsolateral pathways
    Image Upload 2
  14. ventromedial pathways
    Image Upload 4
  15. reflex
    simplest interaction between sensory and motor systems
  16. the status of a muscle is monitored by two receptor systems which are?
    -tendon organs and muscle spindles
  17. Muscle spindles respond more when...
    muslce is stretched because they are in embedded in the muslce itself
  18. stretch reflexes
    when muscles or tendons get stretched there is often an immediate effort by the body to work against that stretch
  19. Withdrawal reflex (3)
    -touch something painful and withdraw immediately

    -motor neurons fire to contractmuscles based on sensory infor from your skin

    *similar to stretch reflexes

    -happens through activation of excitatory and inhibitory interneurons
  20. (withdrawal reflex) Antagonistic muscles
    -muscles that extend the limb and muscles to retract it

    *biceps and triceps
  21. (withdrawal reflex) Reciprocal innervation
    -exciting one muscle while inhibiting the other to make the process fast

    *antagonistic muscles have this
  22. Cortical neurons can also control...
    inhibitory interneurons and prevent reflexes from occuring

    *babinki reflex

    -we have "top down control" over everything
  23. Loss of cortical control...
    can lead to reflexes taking over
  24. Physical stimulus of Chemosensation

    *food, air, fluids
  25. For perception of taste the molecules that interact with...
    taste receptors are in food and drink
  26. For the perception of smell...
    the molecules are airborn
  27. whats does the gustatory system process?
    information about taste
  28. Taste perception begins with the interaction between...
    • molecules and taste receptors that lie within our oral cavity
    • *on the tongue
  29. 5 primary tastes of the gustatory system
    • - sweet
    • -salty
    • -sour
    • -bitter
    • -savory (umami)
  30. (gustatory receptors) tastes are first detetced by specialized receptors called...
    taste buds
  31. where are the taste buds located?
    • they are usually in clusters around papillae
    • *about 5o taste buds per papillae
  32. 4 different types of papillae
    • -fungiform
    • -foliate
    • -circumvallate
    • -filliform

    *they differ in their distribution on the tongue
  33. Image Upload 6
  34. taste buds are made up of...
    • multiple cells that are the taste receptors
    • Image Upload 8
  35. Image Upload 10
  36. taste recpetors react to different tastes
    Image Upload 12
  37. Salty, sour receptorss are activated directly via...
    ion channelsImage Upload 14
  38. (salt and sour receprtors) Na+ of NaCl passes through ion channel to...
    directly depolarize and activate "salty" taste receptor
  39. (salt and sour receptors) H+ of acids passes through ion channels, blocks K+ channels to...
    depolarize and actiivate sour taste receptor
  40. shape of sweet, bitter, or savory chemicals interacts with..
    • receptors on the taste receptor cell
    • *activates G-protein
  41. Each taste buds contains...
    • receptors of all types
    • *proportions vary though
  42. taste fibers seem to encode...
    one taste best  Image Upload 16
  43. 3 Take home message for taste buds preference.
    - activation of the specific receptor is the key

    - activation of that receptors nerve fiber is key

    • -evidence for implication:
    • if we could actiivate a bitter receptor with sugar, we'd experience the sensation of bitter
  44. Stimulation of taste receptors...
    activates taste nerves
  45. (taste nerves) Chorda tympani nerve
    • -innervates anterior 2/3 of tongue
    • *carries information

    Image Upload 18
  46. (taste nerves) Glossopharyngeal nerve
    • innervates posterior third of tongue 
    • *carries information

    Image Upload 20
  47. (taste nerves) Trigeminal nerve
    -codes somatosensory experience of taste
  48. Vision, audition, taste, and touch all use...
    different regions of the thalamus as a relay synapse on way to the cortex
  49. steps to central projections
    - from the tongue, taste efferents project to the rostral part of the nucleaus of solitary tract (NTS)

    -NTS neurons project to taste nucleus in the thalamus (ventral posterior medial, parvocellular)

    Image Upload 22
  50. 3 Individual differences
    -genetic differences in the expression of taste receptors

    • - great variety in the number of fungiform papillae between people
    • *within the fungiform papillae, there is a varibility in the number of "bitter" and pain receptors
  51. Supertaster
    • -better able to detect bitter, find bitter tastes more intense
    • *ability to supertaste is inherited
    • **taste receptor gene
  52. 2 Other difference that supertasters experience
    • - have more fungiform papillae
    • -have more pain receptors
  53. Influences that supertasters have on feeding behaviors
    • -children tend to prefer cereals, sweeter drinks
    • -dont like alcohol, coffee, bitter vegetables
    • -heat/pain from spicy food is more intense
  54. Flavor is comprised of...
    • -taste
    • -odor (olfactory)
    • -texture
    • -temperature
    • -spiciness
Card Set
bio 11
somatosensory and motor systems, chemosensation