Lecture 6 Flashcards
Name the somatic sensory receptor:
Location
nonhairy skin close to surface (fingertips, lips, eyelids, nipples, and external genitalia).
Function
motion detection, grip control
Meissner’s corp
Meissner Corp:
what is the adaptation?
Receptor Field size?
Nerve Fiber type
Rapid (Phasic)
Small most precise
ABx
Name the somatic sensory receptor:
Stimuli
skin motion, low frequency vibration
Meissner Corp:
Name the somatic sensory receptor:
Location
tip of epidermal ridges
Function
form and texture perception
Merkel Disc (nonneuronal)
Name the somatic sensory receptor:
Stimuli
edges, points, corners, curvature
Merkel disc
Merkel Disc:
what is the adaptation?
Receptor Field size?
Nerve Fiber type
slow (tonic)
small
type AB
Pacinian Corpuscle
what is the adaptation?
Receptor Field size?
Nerve Fiber type
very rapid (Phasic)
large
AB
Name the somatic sensory receptor:
Location
dermis and deeper tissues
Function
perception of distant events through transmitted vibrations; tool use
Pacinian
Name the somatic sensory receptor:
Stimuli
vibration (250 Hz is optimal)
Pacinian
Name the somatic sensory receptor:
Location
dermis
Function
tangential force; hand shape; motion detection
Ruffini corp
Name the somatic sensory receptor:
Stimuli
Skin stretch
Ruffini
Ruffini Corpuscle:
what is the adaptation?
Receptor Field size?
Nerve Fiber type
slow (tonic)
large
AB
Free nerve endings (myelinated)
what is the adaptation?
Receptor Field size?
Nerve Fiber type
slow
AB
Free nerve endings (unmyelinated)
what is the adaptation?
Receptor Field size?
Nerve Fiber type
Type C
Name the somatic sensory receptor:’
Location
Surface of body and elsewhere
Function/stimulus
Noxious stimuli, pain, temperature
Free nerve ending (myelinated)
Name the somatic sensory receptor:
Function/stimulus
pain, temperature, itch
Free nerve ending (unmyelinated)
Nociception: Neospinothalamic Tract
What fiber?
NT?
1st order goes to:
2nd crosses:
3rd order goes to:
Adelta
Glutamate
SC
2nd order neuron decussates and passes to the brain in the anterolateral columns.
3rd order neurons go to the cortex.
Does convergence or divergence help to localize sharp pain?
Convergence
Fast pain transmitted through what tract?
Neospinothalamic
Slow pain transmitted through what tract?
Palepspinothalamic tract
Nociception: Paleospinothalamic Tract:
Fibers:
NT:
1st orger goes to:
2nd order:
3rd order goes to:
C fiber
Substance P
SC
2nd order neuron crosses immediately to the opposite side and passes to the brain in the anterolateral columns.
3rd to cortex
**poor localization
Endogenous Analgesia System:
Periaqueductal gray area (midbrain)
Electro stimulation shown to inhibit nociception
Enkephalin Neuron
Serotonergic Neurons
Why are these important?
beta-endorphin, met-enkephalin, leu-enkephalin, dynorphin
Major endogenous opiates
Where are Enkephalins and dynorphin found?
Brain stem and spinal cord
Where are Beta-endorphin found?
found in hypothalamus and pituitary
T/F: Viscera (organs) have few pain fibers
True
T/F: Localized organ damage causes very severe pain
FALSE: Localized organ damage causes very little pain
What is the mechanism of reffered pain? (Viscera pain)
Intermingling of second order neurons in dorsal horn of S.C.
Pain information from the orofacial region is conveyed into the CNS via the ___ and ____
Trigeminospinothalamic Tract and the Trigeminoreticular Tract
T/F: Stimulation of tooth pulp by any kind of stimulus results in a painful sensation.
True
Do teeth have large or small receptor fields?
Large; each of these fibers has extensive branching, such that each afferent nerve innervates multiple teeth…. poor locaalization
Odontoblasts have long processes that are located in the _____ and their cell body is on the surface of the ___
dentinal tubule; dental pulp.
Hypotheses for Dental Nociception:
Cold/Hot
Activation of free nerve endings in dental tube
Neural Theory
Hypotheses for Dental Nociception:
Cold/Hot, Pressure
Fluid displacement activates mechanoreceptors in nerve endings of dentin or pulp.
Hydrodynamicx Theory
Hypotheses for Dental Nociception:
Noxious stimuli
Odontoblasts are excited and transduce the signal to nearby nerve cells
Odontoblast Transducer Theory
dental pulp are predominantly _____________. Dentinal pain is described as ____________.
C fibers
aching pain (Adelta and AB)
Stress can _____ (inc/dec) pain threshold, produce analgesia
increase
Analgesia blocked by opioid antagonist, ____
naloxone (narcan).
Endogenous opioid peptides important in analgesia:
Enkephalins - Tyr-Gly-Gly-Phe-Met(or Leu).
Dynorphins - 13 amino acid peptide.
ß-endorphin - 31 amino acids
“Pain from a non-painful stimulus”
Allodynia –
– “Increased sensitivity to painful stimuli”
hyperalgesia
– “Exaggerated & prolonged pain response”
Hyperpathia
T/F: One type of taste per cell
True
Name the 5 TRCs (possible 6th is fatty)
sweet, salty, sour, bitter, umami
Taste Pathway:
1st Neuron:
2nd:
1⁰ neuron – projects to medulla
2⁰ neuron communicates with thalamus
Population coding – gustatory cortex compares ___ signals
converging
Sweet and Umami (nutritious); Bitter (toxic?),
Stimulus:
Receptor:
Stimulus: chemical ligand
Receptor: GPCR, g-protein gustducin
Sweet and Umami (nutritious); Bitter (toxic?),
signal transduction:
Signal Transduction – resulting in ↑Ca2+.
Signal molecule – in bitter RTCs ATP released via channels
Salty and Sour (pH balance?)
Stimulus:
Receptor:
Stimulus Na+ and H+, respectively
Receptor channels allow ions influx and depolarize TRC
Salty and sour:
signal transduction:
Exocytosis:
Signal Transduction – resulting in ↑Ca2+.
Exocytosis serotonin
Add olfaction?
add
Senory Function: Proprioception
Receptor type:
Muscle spindle
Senory Function: Touch
Receptor type:
Merkel, meissner, pacinian, and ruffini
The somatosensory Cortex is Located in the _____
postcentral gyrus
