Touch (II)

Question 1

labeled lines

Answer 1

the brain recognizes the senses as distinct because their action potentials travel along separate nerve tracts

Question 2

sensory transduction

Answer 2

Conversion of energy from stimulus into a change in membrane potential in a receptor cell

Question 3

receptor (generator) potential

Answer 3

• local change in membrane

- analogous to EPSPs

Question 4

free nerve endigs

Answer 4

pain and temperature

Question 5

merkel’s disc

Answer 5

• somatosensory cell

- touch

Question 6

meissner’s corpuscle

Answer 6

• somatosensory cell

- touch

Question 7

hair follicle receptor

Answer 7

• somatosensory cell

- touch

Question 8

pacinian corpuscle

Answer 8

• somatosensory cell

- vibration and pressure

Question 9

ruffini corpuscle

Answer 9

• somatosensory cell

- stretch

Question 10

proprioceptors

Answer 10

• mechanoreceptors found in tendons
• provide information about changes in muscle tension
• force and position
• “self receptors”

Question 11

sensory events are encoded as _____

Answer 11

streams of action potentials

Question 12

the intensity of a stimulus can be represented by…

Answer 12

the number and thresholds of activated cells

Question 13

stimuli stretching cell membranes opens….

Answer 13

sodium channels which creates a graded generator potential. if this exceeds the firing threshold, an action potential is generated

Question 14

somatosensory system

Answer 14

• determines whether body sensations arise from outside or within the body
• not just in your skin
• surrounds visceral organs

Question 15

how is a stimulus’ location determined?

Answer 15

based on an orderly map like (somatotopically) representation of the position of the activated receptors

Question 16

receptive field

Answer 16

the area within which the presence of a stimulus will alter a sensory neuron’s firing rate.

Question 17

divisions of the spinal cord

Answer 17

cervical
thoracic
lumbar
sacral

Question 18

cervical

Answer 18

neck, arms, shoulders

Question 19

thoracic

Answer 19

trunk

Question 20

lumbar

Answer 20

lower back
front of legs
feet

Question 21

sacral

Answer 21

back of legs/feet

Question 22

dermatome

Answer 22

• region of skin innervated by a particular spinal nerve

- organized by structure

Question 23

what travels in the dorsal column of the spinal cord?

Answer 23

touch and proprioception

pain

Question 24

how does motor information leave the spinal cord?

Answer 24

ventral root

Question 25

dorsal root ganglion

Answer 25

- unipolar neuron cell bodies are outside of the spinal cord | - afferent

Question 26

afferent nerve fibers

Answer 26

carries sensory information into spinal cord

Question 27

dorsal column system/pathway

Answer 27

- delivers touch and proprioception information to brain (soft, rough, vibrating) - doesn't tell you about temperature or pain

Question 28

primary somatosensory cortex

Answer 28

- S1 | - in post central gyrus (in parietal lobe)

Question 29

primary somatosensory cortex

Answer 29

- S1 - in postcentral gyrus (in parietal lobe) - receives touch information from the opposite side of the body - S1 cells arranged as sensory homunculus

Question 30

secondary sensory cortex

Answer 30

- S2 | - receives direct projections from S1

Question 31

where do the S1 axons extend to?

Answer 31

- motor cortex | - sensory association cortices

Question 32

what is the S2 implicated in

Answer 32

tactile learning and memory

Question 33

polymodal neurons

Answer 33

neurons processing information from multiple sensory modalities

Question 34

nociceptors

Answer 34

- peripheral receptors on free nerve endings | - respond to painful stimuli

Question 35

first (Early) pain

Answer 35

- sharp, stinging initial pain feeling | - ex: stubbed your toe

Question 36

how is the first/early pain relayed?

Answer 36

by myelinated A delta axon fibers

Question 37

second (later) pain

Answer 37

- dull, throbbing, lingering pain | - dull pain until the tissue is repaired

Question 38

how is the second/later pain relayed?

Answer 38

by unmyelinated C fibers

Question 39

how are the affective and motivational aspects of second pain mediated?

Answer 39

- by a complex pathway that reaches integrative centers in limbic areas

Question 40

insular cortex (insula)

Answer 40

important pain region

Question 41

periaquaductal gray (PAG)

Answer 41

- important pain region - pain off center - receives info from S1 and S2

Question 42

prefrontal cortex

Answer 42

- long term emotional implications - judgement and decision making - pain

Question 43

anterior cingulate & insulate cortex

Answer 43

- long term emotional consequences - unpleasantness - social rejection - pain

Question 44

primary & secondary somatosensory cortex

Answer 44

- location - intensity - qualities of pain

Question 45

how can pain be modified

Answer 45

- competing tactile sensation, emotion, and cognition

Question 46

what does PAG activation release (via connections with medulla)

Answer 46

endogenous opioids in spinal cord to shut down pain

Question 47

when is the PAG activated?

Answer 47

in threatening situations (momentary reduction in pain increases survival)

Question 48

gate control theory

Answer 48

pain asserts that non-painful input closes the nerve "gates" to painful input, which prevents pain sensation from traveling to the central nervous syst

Question 49

small nerve fibers

Answer 49

- pain axons | - C and A delta fibers

Question 50

large nerve fibers

Answer 50

- touch axons - directly related to brain - shut down ability for pain signals to reach brain

Question 51

placebo response

Answer 51

- expectation of relief from prefrontal cortex - induces release of endogenous opioids in some individuals - increased activity in PAG & prefrontal cortex