Somatosensory

Question 1

what is signal conduction in the nervous system?

Answer 1

conversion of external stimulus into electricity/chemical signals in the NS (occurs at level of sensory receptor)

Question 2

what happens when a sensory receptor is stimulated?

Answer 2

stimulus transduction into the NS (ex pressure receptor pushed down when you touch something)

Question 2

what is somatosensation?

Answer 2

provides us information about what is happening on the surface of our bodies and what is happening internally

Question 3

what are the two somatosensory pathways?

Answer 3

touch and position
pain/temperature

Question 4

what are mechanoreceptors?

Answer 4

senses light touch, pressure, vibration

Question 5

what are Meissner corpuscles’ stimulus and function?

Answer 5

dynamic deformation (skin motion, sensation of rubbing hand on table and feeling it)
very adaptive, rapid adaption

Question 6

what do Pacinian corpuscles detect and what their function?

Answer 6

vibration
rapid adaption

Question 7

what do merkel cells detect? what is their speed?

Answer 7

indentation depth (hod hand to sand paper and feel it)
slow adaption

Question 8

what do ruffini corpuscles detect?

Answer 8

stretch of the skin
slow adapt

Question 9

what are some things mechanoreceptors cancode?

Answer 9

intensity, duration, location and modality of the stimulus

Question 10

what mechanisms do mechanoreceptors use for intensity?

Answer 10

frequency code (how many action potentials are coming in from the sensory receptor being stimulated?)
population code (how many receptors are being stimulated)

Question 11

what is adaption of duration of a stimulus?

Answer 11

process of minimizing sensation of certain sensations (like your cloths touching your skin all day)

Question 12

what are slow adapting receptors good for?

Answer 12

touch discrimination and strech

Question 13

what are fast adapting receptors good for?

Answer 13

motion and vibration

Question 14

how do we encode for stimulus location?

Answer 14

somatic maps (similar to a dermatome)

Question 15

what are receptive fields?

Answer 15

vary in size and density across the body more receptors in close proximity makes more specific reception

Question 16

what is modality?

Answer 16

type or quantity of stimulus energy

Question 17

what is specificity in encoding of motility?

Answer 17

different stimuli are detected by and go through different pathways

Question 18

what is paresthesia?

Answer 18

usually painless and described as tingling or numbness skin crawling or itching (leg falling asleep when you sit on it wrong)

Question 18

what is probilistic receptor specificity?

Answer 18

most sensory receptors are optimally sensitive to singe stimulus energy

Question 19

what is anesthesia?

Answer 19

total loss of sensation

Question 20

what is hypoesthesia?

Answer 20

reduced sense of touch or sensation

Question 21

what pathway does info from touch travel on?

Answer 21

dorsal column / lateral lemniscus pathway

Question 22

where does somatosensory info of the face travel?

Answer 22

trigeminal system

Question 23

what pathway does pain/temp travel on?

Answer 23

anterolateral pathway / spinothalamic tract

Question 24

where are the cell bodies first order neurons of the DCMl pathway?

Answer 24

dorsal root ganglia of spinal nerve, axon enters dorsal spinal cord

Question 25

what dorsal columns does the DCMl pathway travel through and what is the difference between them?

Answer 25

fasciculus gracillis and cuneatis (C is upper bod, Gra is lower)

Question 26

where do the first order neurons of the DCM terminate?

Answer 26

nuc gracills or cuneatus of lower medulla

Question 27

In the DCMI, Axons of second order neurons ascend to the _____ and synapse onto third order neurons in the ________

Answer 27

thalamus ventral posterior lateral nucleus of the thalamus

Question 28

what are the second order neurons of DCMl called?

Answer 28

internal arcuate fibers (cross midline and travel as a path called medial lemniscus)

Question 29

DCML third order neurons project to the

Answer 29

primary somatosensory cortex in the parietal lobe

Question 30

what is the somatosensoy cortex also know as?

Answer 30

A1

Question 31

in the trigeminal system neuron 1 Receives projections from mechanoreceptors in face and oral cavity. THEN Travel to the _____ in the ____

Answer 31

Main Sensory Nucleus in the mid Pons

Question 32

in the trigeminal system Neuron #2 has Axons that project to _________

Answer 32

VPM of thalamus

Question 33

in the trigeminal system the third neurons project to

Answer 33

somatosensory cortex for perception of mechanical touch of face

Question 34

what is pain transmission called?

Answer 34

nociception

Question 35

what are nocieptors?

Answer 35

free nerve endings located in skin (superficial), bones, joints and blood vessels

Question 36

Transduction involves what?

Answer 36

ion channels on the thermoreceptor called Transient Receptor Potential (TRP) channels Opening of channels on nerve ending depolarizes or hyperpolarizes sensory neuron (Na+ or K+)

Question 36

what are thermal receptors?

Answer 36

free nerve endings in the skin that respond to warmth or coolness (detect in diff temp ranges, work best at middle of each receptors range)

Question 37

what does the TRPV2 receptor detect?

Answer 37

noxious heat above 125

Question 38

what does TRPV1 detect?

Answer 38

heat/capsaicin above 109

Question 38

what does TRPV4 detect?

Answer 38

warmth (body heat and blood temp) above 77

Question 39

what does TRPV3 detect?

Answer 39

warmth above 88

Question 40

what des TRPM8 detect?

Answer 40

temps below 82

Question 41

what does TRPA1 detect?

Answer 41

noxious cold below 64

Question 42

what are the two clinical states of pain?

Answer 42

physiological pain (ex pain from injury) neuropathic pain (cause pain from non pain events)

Question 43

what is neuropathic pain?

Answer 43

result from injury to the peripheral or central nervous system that causes permanent changes in circuit sensitivity and CNS connections.

Question 44

where is ceII body of the first order neuron of Anterolateral/ Spinothalamic Pathway

Answer 44

dorsal root ganglia just outside the spinal cord

Question 45

The whole dendrite/axon extension is what kind of fiber?

Answer 45

myelinated AD fiber or an unmyelinated C fiber

Question 46

in the aI/st The axon extends from the cell body in the DRG into the :

Answer 46

dorsal horn of the spinal cord, then travel approx. two vertebral levels

Question 47

Anterolateral/Spinothalamic Pathway, The first order neuron then synapses with secondary neurons in the _________

Answer 47

substantia gelatinosa of Rolando

Question 48

Anterolateral/Spinothalamic Pathway, The spinothalamic tract has somatotopic organization. meaning...

Answer 48

Its cervical, thoracic, lumbar, and sacral components are arranged from most medial to most lateral respectively

Question 49

Anterolateral/Spinothalamic Pathway, The axons decussate to the other side of the spinal cord via the anterior white commissure to the _________

Answer 49

anterolateral corner of the spinal cord.

Question 50

Anterolateral/Spinothalamic Pathway The axons of the second order neurons terminate in the________ and synapse onto third order neurons. From there, signals go to the primary somatosensory cortex, cingulate cortex, and insular cortex.

Answer 50

ventral posteriorlateral thalamus

Question 51

in the trigeminal path nerves synapse with second order neurons that mostly decussate and ascend in the ventral trigeminal thalamic tract to the _________________ to synapse with third order neurons to the face area of the SS cortex

Answer 51

ventral posterior medial nucleus of the thalamus

Question 52

what is the pain matrix in central processing?

Answer 52

many higher order centers of the brain receive pain input at the same time and are able to react based on it

Question 53

what role does S1 play in the pain matrix?

Answer 53

S1 informs pain intensity, modality, and location, but other brain region activities are more closely correlated to the experience of pain

Question 54

what does the anterior cingulate cortex do in pain processing?

Answer 54

part of the limbic system involved in emotional learning

Question 55

what does the insula do in pain processing?

Answer 55

self-awareness, sense of self in pain, sense of visceral pain (gastric distension)

Question 56

what does the prefrontal cortex do in pain processing?

Answer 56

anticipation of pain Activated during placebo effect with PAG

Question 57

what does periaqueductal grey do for pain processing?

Answer 57

important site of endogenous pain inhibition

Question 58

what is the PAG?

Answer 58

hub of pain inhibition PAG stimulates noradrenergic, serotonergic, and opioidergic producing sites, e.g. locus coeruleus (LC), raphe nucleus, and RVM respectively

Question 59

what is allodynia?

Answer 59

pain produced by normally non painful stimui

Question 60

what is hyperalgesia?

Answer 60

heightened response to a pain (hot water feels extra hot when sunburnt)

Question 61

what is Peripheral sensitization?

Answer 61

Peripheral sensitization is a reduction in threshold and an increase in responsiveness of the peripheral ends of nociceptors (due to action of chems)

Question 62

how does Peripheral sensitization work?

Answer 62

-These chemicals can bind to receptors on the distal peripheral nerves and depolarize them closer to threshold -Persistent stimulation can also lead to an increase in Na+ channel number and subtype, and TRP channels, resulting in stronger depolarization events

Question 63

what is Central sensitization

Answer 63

Central sensitization is an increase in the excitability of neurons within the central nervous system, either due to peripheral or central nerve damage and inflammation

Question 64

how does Central sensitization happen?

Answer 64

A burst of activity in nociceptors alters the strength of synaptic connections between the nociceptor and the neurons of the spinal cord (hyperalgesia) * Low-threshold sensory fibers activated by light touch begin to activate neurons in the spinal cord that normally only respond to noxious stimuli (allodynia)