Module 6

Question 1

first-third order sensory neurons

Answer 1

first order: sensory receptor, receives sensation
second order: neuron between first and third
third order: takes second order neuron and transmitts signal to brain

Question 2

how is the location of a stimulation determined?

Answer 2

post central gyrus has a body map that maps onto what region of the cortex is activated

Question 2

what kind of information is transmitted in a sensory receptor?

Answer 2

modality, location, intensity, and duration

Question 3

what does the somatic sensory system detect?

Answer 3

external forces on the body, internal changes, and information about the position of limbs

Question 4

where are somatic sensory receptors?

Answer 4

skin, muscles, tendons, joints, viscera

Question 5

how is the amount of firing determined by senation?

Answer 5

more stretch leads to more action potentials (rate of firing is directly proportional to the magnitude of depolarization)

Question 6

Ia, II afferent axons

Answer 6

fast conductance, large diameter, lots of myelin
use: proprioception, muscle spindle (balance)

Question 7

Ab afferent axon

Answer 7

second most myelin
use: touch, merkel, meissner, pacinian, ruffini cells

Question 8

Ag afferent axons

Answer 8

slowish conductance
Use: pain and temperature

Question 9

C afferent axons

Answer 9

no myelin, slow conductance
Use: pain, temperature, itch

Question 10

what is two point discrimination?

Answer 10

the minimum distance to perceive two stimuli as distinct (smaller is better perception)

Question 11

what does it mean for a receptor to be slow to adapt?

Answer 11

it keeps firing when there is a continuous stimuli

Question 12

what is the mechanosensory pathway for?

Answer 12

touch, vibration, pressure

Question 13

meissner sensory receptors

Answer 13

Detect: movement across skin, slippage of textured objects
adapting: rapidly

corpuscle

Question 14

merkel sensory receptors

Answer 14

detect: edges, points, shapes, texture
adapting: slow
*low two point discrimination in fingertips

also detects pain, temp, no capsulation

Question 15

ruffini sensory receptors

Answer 15

detect: skin strech, hand shape
adapting: slow

corpuscle

Question 16

pacinian sensory receptors

Answer 16

detect: vibrations, tool use
adapting: rapidly

corpuscle

Question 17

conveying mechanosensory info to cortex from periphery afferent pathways

Answer 17

1. two pathways (upper and lower body, cudeate and gracile), end at dorsal column nuclei of medulla
2. jump over to other side, end at VPL nucleus of thalamus
3. end at primary somatosensory cortex (S1)

Question 18

mechanosensory info to cortex from face

Answer 18

1. trigeminal ganlion
2. projects to thalamus
3. VPM nucleus of thalamus

Question 19

what is the procioceptive pathway for?

Answer 19

position of limbs, body parts in space

Question 20

group 1A afferent axons

Answer 20

detect limb movement, muscle changing length

Question 21

group II afferent axons

Answer 21

detect static position (moving and stretching)

Question 22

axonal 1B afferent

Answer 22

measures tendon tension

Question 23

where do procioceptive pathways map to?

Answer 23

reflexes to cerebellum and cortex, everything else to dorsal column nuclei

Question 24

piezo

Answer 24

piezo 2 is usually more important in PNS
structure: two wings, if push down on plates or pull membrane, will open, more than 30 TM regions
use: mechanosensory and proprioceptive pathway
without: don’t respond to pressure, uncoordinated body movements

Question 25

what does the anterolateral pathway detect?

Answer 25

temperature, pain, and non-discriminative touch

Question 26

when do nociceptor’s respond?

Answer 26

when the temperature can lead to tissue damage (responds to higher temperatures than thermoceptors)

Question 27

Ag axons in anterolateral pathway?

Answer 27

for cool temperatures & sharp pain
project to laminae I and V

Question 28

C axons in anterolateral pathway?

Answer 28

for warm temperatures & burning pain
project to laminae I and II

Question 29

pathway of anterolateral pathway from peripheral axons

Answer 29

1. DRG axons terminate at dorsal horn of spinal cord, immediately synapse w 2nd order neurons
2. jump sides, descend spinal cord to VPL nucleus of thalamus
3. project to S1

Question 30

pathway of anterolateral pathway from face

Answer 30

1. to trigeminal nerve and terminate in SNTC
2. jump sides VPM of thalamus

Question 31

noxious stimuli

Answer 31

hot/ cold, tissue damaging

Question 32

receptors for temp

Answer 32

TRP

Question 33

receptors for chemicals

Answer 33

TRP, ASIC

Question 34

receptors for mechanical stimulation

Answer 34

TRP, ASIC, Piezo’s

Question 35

TRP family

Answer 35

chili: TRPV1 and TRPV2
nociceptors: TRPV1

Question 36

how does pruciception progress?

Answer 36

scratch –> prutigens (histamines and drugs)
ex. opioids lead to itch

Question 37

how does pain and itch override?

Answer 37

pain overrides itch (ex. slapping a mosquito bite)

Question 38

how to control mild pain?

Answer 38

target peripheral inflammation (progastines)

Question 39

how to control moderate to severe pain?

Answer 39

target nervous system

Question 40

gate theory of pain

Answer 40

activation of mechanoreceptors modulates transmission of nociceptive information (why counter pressure works)