Chapter 14 Flashcards

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1
Q

What is the breakdown of the somatosensory system?Include the three parts

A

1) Cutaneous senses
- >touch and pain

2) Proprioception
- >sense body position and limb position

3) Kinesthesis
- >movement of body and limbs

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2
Q

What is the heaviest organ of the body?

A

-the skin

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3
Q

What is the layer of dead skin cells? What layer is below it?

A
  • the layer of dead skin cells is the epidermis

- below it is the dermis

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4
Q

Where are mechanoreceptors found?

A

-in the dermis and the epidermis

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5
Q

What are Merkel receptors referred to? Do they have a large receptive field?

A
  • slowly adapting fiber
  • SA1 fibers
  • the nerve fiber fires continuously as long as the stimulus is on
  • have a small cutaneous receptive field

-involved with fine details, texture and shape

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6
Q

What are Meissner corpuscle receptor referred to? Do they have large receptive fields?

A
  • fast adapting fibers
  • RA1
  • the nerve fiber fires only when the stimulus is applied and when it is removed

-involved with handgrip control, and perceived motion across the skin

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7
Q

Describe the Ruffini cylinder

A
  • it is a mechanoreceptor
  • > fires to stretching
  • a SA2 fiber
  • deeper in the skin
  • > has a larger receptive field than Merkle and Meissner
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8
Q

Describe the Pacinian corpuscle

A
  • it is a mechanoreceptor
  • a RA2 fiber
  • deeper in the skin
  • responds to biration
  • fine texture moving across the fingers
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9
Q

Differentiate th emedial lemniscal pathway and the spinothalamic pathway

A
  • lemniscal pathway has large fibers
  • > carry signals related to proprioception and perceiving touch
  • spinothalamic pathway carries signals related to pain and temperature
  • > smaller fibers
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10
Q

Are there pain receptor in the brain

A

-no

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11
Q

What is the homunculus

A

-it shows the areas of the skin that project to areas of the brain

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12
Q

How does using a function more often contribute to its cortical organization

A
  • if a function is used more often

- >that area of the cortex becomes larger

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13
Q

What is the Braille characters used for

A
  • it is used by blind people to read
  • consists of a cell made up of one to six dots
  • different arrangements represents different letters of the alphabet
  • all of this depends on tactile detail perception
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14
Q

How does grating acuity relate to Merkel receptors and Paccinian receptors

A

-better acuity is associated with less spacing between Merkel receptors

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15
Q

How does the cortex relate to tactile acuity

A
  • there is a relationship between tactile acuity and the cortical homunculus
  • > the smaller the receptive field
  • > the less the overlap in the cortex
  • > so more firing of neurons in the cortex
  • eg; fingers have small receptive fields
  • > so the neurons in the cortex wouldn’t overlap and would fire separately
  • > can’t say the same for the receptive fields of an arm
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16
Q

Why does the Pacinian receptor respond to rapid vibrations but not constant stimulations

A
  • due to the corpuscle fibers
  • > they have a series of layers
  • > fluid between each layers
  • > transmits rapidly repeated pressure like vibrations
  • > does not transmit continuous pressure
  • therefore, the pacinian responds well
  • > at the beginning when a stimulus first fires
  • > and when the stimulus ends

-or it responds well to a vibration

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17
Q

What is surface texture

A

-it is the physical texture of a surface created by peaks and valleys

18
Q

What provides a more accurate assessment of surface texture? Touch or vision?

A

-touch

19
Q

Describe the duplex theory of texture perception

A
  • perception of texture depends on
  • > spatial cues
  • > temporal cues
20
Q

What are spatial cues

A
  • provided by large surface elements
  • > eg; bumps and grooves
  • > felt when the skin moves across surface elements
  • > feel different shapes, sizes and distribution of surface elements
21
Q

What are temporal cues

A
  • fingers moved across textured surface
  • > like fine sandpaper
  • > perception of fine texture that cannot be detected unless the fingers are moving across the surface

-fine textures sensation was due to the role of vibtation

22
Q

How does adapting the Pacinian corpuscle receptor affect our ability to tell the difference between two fine textures

A
  • it removes that ability

- Pacinian receptors play a huge role in temporal cues

23
Q

Contrast active touch with passive touch. What kind of perception do you engage in the active touch.

A

Active touch

  • > touch in which person actively explores an object
  • > with fingers and hands
  • > you engage in haptic perception
  • > experience the objects you are touching

Passive touch

  • > when touch stimuli are applied to the skin
  • > experience stimulation of the skin
24
Q

Describe the haptic perceptual system. What parts of the body work together in this system?

A

-it is when the sensory system, the motor system and the cognitive systems work all together

25
Q

What are exploratory procedures

A
  • people use a number of distinctive movements
  • > when they are involved in the process of active touching
  • these distinc movements are exploratory procedures
26
Q

What kind of receptive fields do ventral posterior thalamus neurons respond to

A

-they respond to center surround receptive fields

27
Q

What kind of receptive fields have been found in the somatosensory cortex of monkeys

A
  • center-surround
  • others that respond more to specialized stimulation of the skin
  • > eg; neurons that respond to specific orientations
  • > neurons that respond to movement across the skin in a specified direction
  • > neurons that respond to monkeys grasping a specific objects
28
Q

How does attention affect cortical responding?

A

Without attention or being distracted

  • > the stimulation of receptors may trigger a response
  • > but the size of the response can be affected by the processes such as attention, thinking and other actions of the perceiver
  • attention influences what stimuli stimulate the receptors
  • it also stimulates the processing that occurs once the receptors are stimulated
29
Q

How does watching someone else be touched affect the somatosensory cortex?

A

-it activates areas in the somatosensory cortex of the observesr that would also be activated in the somatosensory cortex of the person actually being touched

30
Q

What are the three types of pain? Describe them

A

1) Inflammatory Pain
- >damage to tissue
- >tumor cells
- >inflammation of joints

2) Neuropathic Pain
- >caused by lesions or damage to the nervous system
- >eg; carpal tunnel syndrome

3) Nociceptive pain
- >activation in the receptors called nociceptors
- >responds to tissue damage or potential damage

31
Q

Describe the direct pathway model of pain

A
  • pain occurs when nociceptor receptors in the skin are stimulated
  • > send their signals directly from the skin to the brain
  • > but not all pain arises from damage to the skin

-cannot explain phantom limbs

32
Q

Describe Phantom Limbs

A
  • pain occurs without any transmission from receptor to brain
  • > occurs with people who have had limb amputations
  • signals are still sent from part of the limb that remains gone
  • > cutting the nerves that used to transmit signals from the limb to the brain does not eliminate the phantom limb or the pain
33
Q

Describe the gate control model to pain

A
  • pain signals enter the spinal cord from the body
  • > then move from the spinal cord to the brain
  • > there are additional pathways that influence the signal from the spinal cord to the brain
  • > these additional pathways can act as a gate

-note the dorsal horn of the spinal cord controls the pain coming up to the spinal cord

34
Q

How does input occur to the gate control system along three pathways

A

1) Nociceptor
- >fibers from nociceptors activate a circuit consisting entirely of excitatory synapses
- >send excitatory signals to the transmission cells
- >excitatory signals in the dorsal horn open the gate
- >increase the firing of transmission cells

2) Mechanoreceptors
- >nonpainful tactile stimulation
- >signals from these receptors reach the innhibitory neurons in the dorsal horn
- >inhibitory signals are then sent to transmission cells
- >this closes the gate
- >decreases the firing of transmission cells

3) Central control
- >fibers
- >carry signals down from the cortex
- >activity coming down from the brain closes the gate
- >decreases transmission cells activity

35
Q

What is the placebo effect

A
  • decrease in pain from a substance that has no pharmacological effect
  • > patient believes that the substance is effective therapy
  • > decrease in pain from a positive efffect
36
Q

What is the nocebo effect

A
  • negative placebo effect
  • negative expectation instructions
  • > results in negative effect
37
Q

Can attention be used to distract an individual from a sense of pain

A
  • yes

- >for example, burn victims using virtual reality techniques

38
Q

Can emotions play a role in pain

A
  • yes
  • > more positive emotions=less perception of pain
  • > eg; looking at pleasant pictures and not being reminded that your whole god damn hand is in a bucket of ice
  • > same experiment occurred with shocks

-there is also evidence that listening to positive music can decrease the sensation of pain

39
Q

Describe the multimodal nature of pain

A
  • pain is a sensory and emotional experience
  • > proven by how people describe pain
  • sensory= throbbing, prickly, hot, or dull
  • emotional=torturing, annoying, frightful or sickening
  • changes with sensory component is involved in the somatosensory cortex
  • changes in the emotional aspect is involved in the anterior cingulate cortex
40
Q

How does nalaxone work

A
  • it attaches to same receptor sites as heroin
  • > because it has a similar structure
  • > therefore, preventing heroin from binding to those receptors
  • it can increase pain
  • > as it prevents the binding of opioids
  • > it also decreases the analgesic effect of placebos
41
Q

What are endorphins

A
  • naturally occuring morphine

- >endogenous morphine

42
Q

Is the placebo effect related to endorphin release?

A
  • yes
  • > because increasing nalaxone decreased this effect
  • the brain can signal specific areas in the body where there will be pain
  • > therefore, release endorphins in these areas
  • > creating th eplacebo effect