piri somatosensation Flashcards
what are the nonencapsulated types of receptors
nociceptors and pain receptors
pacinian
highly sensitive to vibration, located in the dermis, textures, fast adapting
meissner
small receptor field, fast adapting, most common in glabrous skin, low frequency vibration/skin motion
A beta receptors
transmit tactile information
A alpha fibers
A delta fibers
DOUBLE CHECK:initial fast transmission of pain (type 1 low threshold temperature and type 2 low threshold mechanical and chemical)
-myelinated fibers
C fibers
responds to all pain, subtype preferences for heat, chemical etc
-unmyelinated
what region of the cortex receives most somatosensory information
3b
what is the medial lemniscus pathway and what information does it carry
-pseudunipolar somatosensory touch receptor cells go through the dorsal root ganglion and extend up the medial dorsal root column.
-in the medulla, these first order pseudounipolar cells synapse with the dorsal column nuclei.
-the second order dorsal column nuclei decussate in the midbrain and synapse in the VPL thalamus.
-VPL thalamus third order neurons terminate in the somatosensory cortex 1 and 2.
this pathway conveys tactile information about touch, pressure, vibration
what is the spinothalamic/anterolateral pathway and what kind of information does in convey
-the spinothalamic pathway conveys information about nociception and temperature
-pseudounipolar ganglion cells from the periphery extend through the dorsal ganglion to the laminae 1/5. They decussate. Then these second order neurons project to the brainstem.
-From the brainstem, 3rd order extend to the thalamus.
trigeminal pathway
-pseudounipolar neurons project from the periphery to the principal trigeminal nuclei
-second order neurons extend from the trigeminal nuclei to the ventral posterior medial nuclei of the thalamus. These decussate.
-third order neurons extend from the thalamus to the somatosensory cortex
-conveys tactile information about the face
what cranial nerves travel along the trigeminal pathway
cranial nerves 7, 9, 10
which section of the laminae receive both cutaneous and nociceptive (multimodal) information
laminae 5
type 1 a delta fibers
respond to mechanical and chemical stimulation
type 2 a delta fibers
respond to temperature stimulation
where does integration in the somatosensory cortex take place
posterior parietal cortex,
what is integrated in the somatosensory cortex
streams of somatic sensation information, visual stimuli, and movement planning
gracile tract
axons of neurons which carry information about somatosensation in the lower body, gracile column nuclei located in the dorsal column nuclei
cuneate tract
axons of neurons which carry information about somatosensation in the upper body, cuneate column nuclei located in the dorsal column nuclei
what cranial nerve carries information about the face
nerve 10
what happens as a result of a lesion to the PPC
agnosia (inability to recognize objects)
phantom limb syndrome
what are the components of inflammatory soup
bradykinin (depolarizes nociceptors), prostoglandins(increases sensitivity of nociceptors to other stimuli), substance P(causes the release of histimine), 5HT, H+
hyperalgesia
release of too much inflammatory soup
what is the importance of the descending somatosensory pathway
still unclear but mostly to regulate and refine the ascending pathways
how do opioids work
they suppress the release of glutamate and also cause the inhibition of postsynaptic neurons in the spinothalamic pathway
what is the visceral pain pathway
-peripheral first order pseudounipolar cells synapse with axons in the intermediate gray region of the spinal cord
-second order axons extend from the intermediate gray region near the gracile nuclei in the dorsal column
-third order neurons decussate along the medial lemniscus to the VPN in thalamus
-fourth order neurons extend from the thalamus to the insular cortex
the visceral pathway carries information about visceral (internal) pain
what happens when you eat a hot pepper
capsaicin, a compound in peppers, acts as a ligand for the VR-1 temperature receptor
-this receptor is opened and the temperature sensitive cell is activated
what fibers are cold receptors coupled with
a delta and c
what fibers are hot receptors coupled with
c fibers
