Cutaneous senses - chapter 15

Question 1

what are the cutaneous senses

Answer 1

everything we feel through the skin

Question 2

what happened to Ian Waterman

Answer 2

due to an autoimmune reaction, he lost the ability to feel skin sensations

Question 3

what were some of Waterman’s disabilities

Answer 3

could not grasp objects, could not sense the position of his limbs

Question 4

what sensations did Waterman still have

Answer 4

pain and differences in temperature

Question 5

what are the 3 parts of the somatosensory system

Answer 5

cutaneous senses, proprioception, and kinesthesis

Question 6

what are the cutaneous senses

Answer 6

perception of touch and pain from skin stimulation

Question 7

what is proprioception

Answer 7

awareness of where your body is in space (position of limbs)

Question 8

what is kinesthesis

Answer 8

ability to sense movement of the body and limbs

Question 9

what is the heaviest organ in the body

Answer 9

skin

Question 10

what are the 3 layers of the skin (outermost to innermost)

Answer 10

epidermis, dermis, hypodermis

Question 11

what are mechanoreceptors

Answer 11

receptors that respond to mechanical stimulation (pressure, stretching, vibration, etc.)

Question 12

which two mechanoreceptors are located close to the surface of the skin

Answer 12

Merkel and Meissner

Question 13

do the Merkel and Meissner receptors have small or large receptive fields

Answer 13

small because they are located to close to the skin’s surface

Question 14

what is the cutaneous receptive field

Answer 14

area of the skin that when stimulated influences the firing of neurons

Question 15

what kind of fibre is the Merkel receptor

Answer 15

slowly adapting fibre (SA1)

Question 16

what is the Merkel receptor’s response to stimulation

Answer 16

constant firing until stimulus is removed (SA1)

Question 17

what kind of nerve fibre is the Meissner receptor

Answer 17

rapidly adapting fibre (RA1)

Question 18

what is the Meissner receptor’s response to stimulation?

Answer 18

it fires once the stimulus is first applied and when it’s removed

Question 19

what is the Merkel receptor perceptually responsible for

Answer 19

sensing fine details, shape, and texture

Question 20

what is the Meissner receptor perceptually responsible for

Answer 20

controlling hand-grip and perceiving motion across the skin

Question 21

what 2 mechanoreceptors are located deep in the skin

Answer 21

Ruffini cylinder and Pacinian corpuscle

Question 22

what is the similarity between the Merkel receptor and the Ruffini cylinder

Answer 22

they are both slowly adapting fibres (ruffini cylinder = SA2 and they both constantly fire to stimulation

Question 23

what is the similarity between the Pacinian corpuscle and the Meissner receptor

Answer 23

both rapidly adapting fibre (Pacinian corpuscle = RA2) and they both fire only when the stimulus is first applied and removed

Question 24

do the Ruffini cylinder and the Pacinian cylinder have small or large receptive fields

Answer 24

large because they are located deep in the skin

Question 25

what is the Ruffini cylinder perceptually responsible for

Answer 25

perceiving stretching of the skin

Question 26

what is the Pacinian corpuscle perceptually responsible for

Answer 26

sensing rapid vibrations and fine texture

Question 27

signals from the body are transmitted where first

Answer 27

the spinal cord

Question 28

how many segments does the spinal cord have

Answer 28

31

Question 29

how does the spinal cord receive signals

Answer 29

the dorsal root

Question 30

signals from the spinal cord are transmitted to the brain along which 2 major pathways

Answer 30

medial lemniscal pathway and spinothalamic pathway

Question 31

what kind of fibres does the medial lemniscal pathway have and what kind of signals does it carry

Answer 31

this pathway has large fibres (high speed) and they carry signals related to proprioception and touch

Question 32

what kind of fibres does the spinothalamic pathway have and what kind of signals does it carry

Answer 32

small fibres and they carry signals related to pain and temp

Question 33

which pathway from the spinal cord to the brain was damaged in Ian Waterman's case

Answer 33

the medial lemniscal pathway

Question 34

what happens to the fibres from both pathways in their journey from the spinal cord to the brain

Answer 34

they cross over (contralaterally) and synapse in the thalamus

Question 35

what part of the thalamus do fibres from the cutaneous senses synapse in

Answer 35

ventrolateral nucleus

Question 36

what are the 2 areas that receive signals from the thalamus and which lobe are they located in

Answer 36

primary somatosensory cortex (S1) and secondary somatosensory cortex (S2) located in the parietal lobe

Question 37

what is an important characteristic of the somatosensory cortex

Answer 37

it is organized into maps that correspond to locations on the body

Question 38

what is the Jacksonian march

Answer 38

Hughlings Jackson observed that in some seizures it starts in one place and spreads to neighbouring body parts until the whole body is affected (progressed in an orderly manner)

Question 39

what is the homunculus and what does it represent

Answer 39

it is a body map of the cortex that shows adjacent parts of the skin project onto adjacent parts of the brain and some areas of the skin are represented by disproportionately large brain areas

Question 40

what is tactile acuity

Answer 40

the capacity to detect details of stimuli presented to the skin

Question 41

what is the two-point threshold

Answer 41

the minimum separation between 2 points on the skin for them to be perceived as two points

Question 42

how is grating acuity measured

Answer 42

by pressing a grooved stimulus onto the skin and asking the person to indicate the orientation of the grating

Question 43

what is raised pattern identification

Answer 43

pushing raised patterns (ex: letters) onto the skin and seeing the smallest-sized pattern/letter that can be identified

Question 44

there is a high density of which receptor in the fingertips

Answer 44

Merkel receptor (details)

Question 45

which mechanoreceptor is primarily responsible for sensing vibration

Answer 45

Pacinian corpuscle

Question 46

which theory did Katz (1925) propose

Answer 46

the duplex theory of texture perception

Question 47

what is the duplex theory of texture perception

Answer 47

our perception of texture depends on spatial and temporal cues

Question 48

what are spatial cues

Answer 48

relatively large spatial elements that can be felt when skin moves against it and when the skin is pressed on the elements

Question 49

give an example of spatial cues

Answer 49

braille

Question 50

what are temporal cues

Answer 50

fine texture (vibrations) can only be detected when our fingers are moving along its surface

Question 51

give an example of temporal cues

Answer 51

sandpaper

Question 52

what is active touch

Answer 52

touch where a person actively explores an object with their fingers/hands

Question 53

what is passive touch

Answer 53

when touch stimuli is applied to the skin

Question 54

what is haptic perception

Answer 54

perception where you explore 3-D objects with your fingers/hands (active touch)

Question 55

haptic perception involves which 3 systems

Answer 55

sensory(detecting touch sensations on fingers), motor(moving fingers/hands), and cognitive (thinking about the info provided from sensory and motor systems)