Chapter 14: Touch and Pain Flashcards
(117 cards)
1
Q
Epidermis:
A
the outer layer of the skin
2
Q
Dermis:
A
the inner layer of the skin, which also houses touch receptors
3
Q
Mechanoreceptors:
A
the sensory receptors in the skin that transduce physical movement on the skin into neural signals, which are sent to the brain
4
Q
SAI mechanoreceptors:
A
slow-adapting receptors using Merkel cells, with small receptive fields, densely packed near the surface of the skin
5
Q
SAII mechanoreceptors:
A
slow-adapting receptors using Ruffini endings, with large receptive fields, more widely distributed, deeper in the skin
6
Q
FAI mechanoreceptors:
A
fast-adapting receptors, with Meissner corpuscle endings and small receptive fields, densely packed near the surface of the skin
7
Q
FAII mechanoreceptors:
A
fast-adapting receptors with Pacinian corpuscle endings and large receptive fields, more widely distributed, deeper in the skin
8
Q
Meissner corpuscles:
A
specialized transduction cells
in FAI mechanoreceptors
9
Q
Pacinian corpuscles:
A
specialized transduction cells in FAII mechanoreceptors
10
Q
Merkel cells:
A
specialized transduction cells in SAI mechanoreceptors
11
Q
Ruffini endings:
A
specialized transduction cells in SAII mechanoreceptors
12
Q
Proprioception:
A
the perception of the movements and position of our limbs or in other words our perception or awareness of how our bodies are positioned. If one loses their proprioception system then one won’t be aware of how their limbs are moving and where it is in space.
13
Q
Muscle spindles:
A
receptors embedded in the muscles that sense information about muscle length and therefore muscle action
14
Q
Joint receptors:
A
receptors found in each joint that sense information about the angle of the joint
15
Q
What are the three cells that provide infromation about limb movement and position?
A
muscle spindles, joint receptors, and golgi tendon organs
16
Q
Golgi tendon organs:
A
receptors in the tendons that measure the force of a muscle’s contraction
It is important that the golgi tendon organs measure the force as it provides information of how many muscle fibers are used and how much more force has been applied by the muscle. This is important in order to be aware of how much force or strength is being applied when patting someone’s back or giving someone a handshake.
17
Q
Afferent fibers:
A
neural fibers that carry sensory information to the central nervous system
18
Q
Thermoreception:
A
the ability to sense changes in temperature on the skin
19
Q
Thermoreceptors:
A
the sensory receptors in the skin that signal information about the temperature as measured on the skin
– They respond to a range of skin temperatures from 63* to 109*
– Skin temperatures above 109* and below 64* are experienced as pain
20
Q
Cold fibers:
A
thermoreceptors that fire in response to colder (30 °C and below/86* and lower) temperatures as measured on the skin
At intermediate temperatures (between 86* and 97*) cold and warm fibers fire at steady state
21
Q
Warm fibers:
A
thermoreceptors that fire in response to warmer temperatures (above 36 °C/97* and higher) as measured on the skin
At intermediate temperatures (between 86* and 97*) cold and warm fibers fire at steady state
22
Q
Cold and warm fibers also fire when you
touch objects that are colder or warmer
than your skin temperature. T/F
A
T
23
Q
What is Paradoxical heat experience?
A
Warm fibers have a “secondary peak” –
also fire when exposed to very low
temperatures
Very cold things may feel burning hot or
painful
24
Q
Pain:
A
the perception and unpleasant experience of actual or threatened tissue damage
25
Nociceptive pain:
pain that develops from tissue damage that causes nociceptors in the skin to fire
26
Nociceptors:
sensory receptors in the skin that, when activated, cause us to feel pain; they are found in both the epidermis and the dermis
27
Tissue damage causes ____________ to fire
nociceptors
28
Nociceptors are divided into two main
types that are...
A-delta fibers; C-fibers
29
A-delta fibers:
myelinated nociceptors that conduct signals fast/rapidly and respond to both heat and pressure
Stinging, instant feeling of pain
30
C-fibers:
nonmyelinated/unmyelinated nociceptors that conduct signals more slowly or are slower.
Respond to pressure, extreme degrees of either heat or cold, and toxic chemicals
Chronic, throbbing pain. May be
delayed
31
Why does scratching relieve the itch
feeling?
– Scratching reduces itch because pain suppresses itching
– Ironically, itching reduces pain
32
Perception of ____ is related to pain, but different receptors.
itch
33
The brain’s response to painful stimulation is often to release ___________.
endorphins
– Frontal Lobe-takes into account situation
– Sends message to top of brainstem, and that sends inhibitory message through spinal cord down to where the pain is
located
34
Dorsal root ganglion:
a node on the spine where one finds nerve cells carrying signals from sensory organs toward the somatosensory areas of the brain
35
Dorsal root:
the end of the spinal nerve where sensory information enters the spinal cord
36
Ventral root:
the end of the spinal cord where motor information leaves the spinal cord
37
Dorsal:
in or toward the back of the body; in the head, it means at the top or toward the top
38
Ventral:
in or toward the front of the body; in the head, it means at the bottom or toward the bottom
39
Dorsal column–medial lemniscal pathway:
Carries info from mechanoreceptors and proprioceptors
a pathway for the mechanoreceptors (tactile perception) and proprioceptors (muscle position) that travels up the spinal column on the ipsilateral side and crosses to the contralateral side in the medulla
40
Ipsilateral:
literally, same (ipsi) side (lateral), meaning, in this context, that sensory information is on the same side of the nervous system as it entered
41
Contralateral:
literally, opposite (contra) side (lateral), meaning, in this context, that sensory information is on the side of the nervous system opposite the one from which it entered
42
Somatosensory cortex: an
area in the parietal lobe of
the cerebral cortex devoted
to processing the information
coming from the skin senses
in parietal lobe, devoted to processing information from skin senses
43
Ventral posterior nucleus of the thalamus:
an area in the thalamus that receives input from both the dorsal column–medial lemniscal pathway and the spinothalamic pathway
44
Spinothalamic pathway:
Carries info from the nociceptors and thermoreceptors
a pathway for the nociceptors (pain) and thermoreceptors (temperature) that travels up the contralateral side of the spinal column; does not synapse in the brain until the ventral posterior nucleus of the thalamus
45
Somatotopic map:
a feature whereby the skin of the body maps onto the surface of the primary somatosensory cortex in a systematic way
46
Homunculus:
a drawing of a human in which the proportions of the body parts match the relative sizes each body part has on the somatotopic map.
47
Brain can inhibit information from _____________.
nociceptors
48
Gate control theory:
a model that allows for top-down control of the pain signal coming up the spinal cord
– Downward pathway from brain to spinal column
– Activation can inhibit flow of info from nociceptors to brain
– Pain can be reduced or inhibited
49
Substantia gelatinosa:
the region in the dorsal horn where neurons meet
50
Dorsal horn:
an area of the spinal cord that receives input from nociceptors and feedback from the brain
51
Anterior cingulate cortex:
a region in the prefrontal lobe of the brain associated with the emotional experience of unpleasantness during pain perception
52
Endogenous opioids:
chemicals produced by the body that reduce pain throughout the body
53
Analgesia:
processes that act to reduce pain perception
54
Pruriceptors:
receptors in our skin that respond to mild irritants by producing itch sensations
perhaps mix of mechanorecptor and chemical receptor
– Possible interaction with histamines
* Goal may be to induce minor tissue damage to initiate immune system
– Or, scratch away the irritant
55
Haptic perception:
the active use of touch to identify objects
56
Exploratory procedures:
hand movements made in order to identify an object
57
Tactile agnosia:
an inability to identify objects by touch
58
Vestibular system:
the sensory system responsible for the perception of balance and acceleration, housed in the semicircular canals and otolith organs, both located adjacent to the inner ear
59
Semicircular canals:
three tubes located in the inner ear responsible for the signaling of head rotation
60
Otolith organs:
organs responsible for detecting acceleration of the head and identifying when the head is being held at a tilted angle
61
Endolymph:
fluid that fills the semicircular canals
62
Ampulla:
the structure at the base of each semicircular canal that contains the crista
63
Crista:
the structure in the ampulla of each semicircular canal that contains the receptors
64
Macula:
the structure in the otolith organs that contains the receptors
65
Vestibular complex:
a brain stem area that receives input from the vestibular nerve and sends the information to the forebrain
66
Parietal insular vestibular cortex:
an area in the parietal lobe that receives input from the vestibular nerve and is responsible for the perception of balance and orientation
67
Electroreception:
the ability to detect electric fields, seen in many species of fish
68
Passive electroreception:
the ability only to detect electric fields
69
Active electroreception:
the ability to generate electric fields and then detect disturbances or changes to those electric fields caused by external events
70
Ampullae of Lorenzini:
the organ that contains the hair cells that detect electric fields, used in passive electroreception
71
Tuberous receptor:
the organs that contain the hair cells that detect electric fields, used in active electroreception
72
Phantom limb syndrome:
continued but illusory sensory reception in a missing appendage
73
Phantom limb pain:
refers to experiencing pain in a limb that has been amputated
74
Visual capture
circumstances where visual input can dominate the input from other senses when they conflict
75
1-24
76
Which mechanoreceptors are critical for blind individuals who use braille?
SAI mechanoreceptors
77
Which mechanoreceptors are responsible for two-point thresholds?
SAI mechanoreceptors
78
Where are a few locations where we find a high density and low density of SAI mechanoreceptors?
the fingertips and the lips for high density
the back and legs for low density
79
Identifying an object through the sensation of touch is called ______.
haptic perception
80
Touch includes multiple sensory systems. T/F
True
81
The outer layer of skin is called the ______.
epidermis
82
The sensation of itch ______.
can be so intense that it is debilitating
83
Pruriceptors and nociceptors both ______.
synapse in the somatosensory cortex
84
The sensory system that monitors balance and acceleration is the ______ system.
vestibular
85
Most touch receptors reside in the dermis. T/F
true
86
When pruriceptors sense an irritant, they produce a sensation of ______.
itch
87
There are four individual pathways from the spinal column to the brain. T/F
False, there are two
88
Itchiness usually signals a serious underlying disorder. T/F
False
89
Why is the sense of touch called a "proximal" sense? What are examples of "distal senses"?
Touch is a proximal sense due to it requiring direct bodily contact and bodily movement. An example of distal sense is that of vision, audition, and olfaction since they all can work at a distance.
90
Describe the four types of mechanoreceptors.
The four types of mechanoreceptors are the SAI mechanoreceptors (Merkel Cells), the SAII mechanoreceptors (Ruffini endings), the FAI mechanoreceptors (Meissner corpuscles), and the FAII mechanoreceptors (Pacinian corpuscles).
The SAI and SAII are slow-adapting mechanoreceptors, while the FAI and the FAII are fast-adapting mechanoreceptors. The ones that have a Roman numeral I are those that have smaller receptive fields, while the II mechanoreceptors have larger receptive fields.
The SAI and SAII continuously respond to a touch, while FAI and FAII respond only when initially touched and the touch has ended.
SAI and FAI receptors are located close to the skin's surface, have small receptive fields, and are are densely packed of receptors. All the the characteristics that were previously stated is what gives them high spatial resolution, giving us the ability to detect where a stimulation is occurring.
In contrast the SAII and FAII receptors are located deeper in the skin, have larger receptive fields with more dispersed receptors. This results in their spatial resolution being less than the SAI and FAI mechanoreceptors. Despite them not being able to detect an exact location, they are highly sensitive to light touch.
91
What type of stimulation is the Meissner corpuscle known to detect?
heavy pressure
92
What type of stimulation is the Pacinian corpuscle known to detect?
Vibration
93
What type of stimulation is the Merkel disks known to detect?
Light touch
94
What type of stimulation is the Ruffini endings known to detect?
skin stretch
95
Describe the difference between slow-adapting and fast-adapting mechanoreceptors. How is each important for perceiving different aspects of the perceptual world?
Slow-adapting mechanoreceptors produce a steady response to the whole duration of stimulation, whereas the fast-adapting mechanoreceptors only produce a response when the stimulation starts and then when it stops.
Slow-adapting mechanoreceptors are important for us to know whether there is a continuous stimulation occurring, and fast-adapting mechanoreceptors are important for us to detect sudden changes on our skin.
96
Why is it likely that animals, such as ourselves, evolved to have two separate systems, one for detecting cold and one for detecting heat? What advantages does that have over just one system that detects temperatures on a continuous scale, like a thermometer?
97
Describe the differemce between A-delta fibers and C-fibers. How does each contribute to the perception of pain?
98
What is the somatosensory cortex? Where is it and what is its primary function?
It is located in the parietal lobe of the brain specifically in the postcentral gyrus. Its primary function is to process sensory infromation from the body including touch, pressure, temperature, and pain it creates a map of the body where different regions correspond to different body parts.
99
How is the somatosensory cortex organized?
Topographically, meaning body parts or represented in specific areas, the amount of cortical space dedicated to a body part corresponds to its sensitivity.
100
How do endogenous opiods work?
They naturally produce chemicals in the brain that bind the opiod receptors. They inhibit the transmission of pain signals in the spinal cord and brain reducing pain perceptions. They also contribute to feelings of well-being or euphoria.
101
What type of receptor is responsible for feeling "itch"?
Pruriceptors, these are located in the skin and inform us of any chemical or bodily change on the skin. Histamines also are responsible for most itches or something like a mosquito bite, where for us the reaction of getting bit by a mosquito is an itch that these receptors tell our brain about.
102
What is "haptic" perception? How is it different from simple touch perception?
103
Neuron clusters:
lots of cell bodies clustered together
In CNS called “Nucleus”
In PNS called “Ganglion”
104
Sensory neuron cell bodies are located _________ the spinal cord.
outside and they are called "dorsal root ganglia"
105
Motor neauron cell bodies are located __________ the spinal cord.
inside, in gray matter , ventral roots carry motor info away from spinal cord
106
Gray matter is located in the _________ of the spinal cord.
center
107
Gray matter is...
densely packed with cell bodies and dendrites
108
Where is white matter located?
on the sides of gray matter
109
What does white matter consist of?
consists of mostly myelinated axons
110
What is the Bell-Magendie law?
States that:
* Dorsal roots (back axon bundles) enter the spinal cord carrying info from sensory organs (e.g. skin);
* Ventral roots (front axon bundles) exit the spinal cord carrying motor information to muscles and glands
111
What are the two neural pathways once in spinal column?
1) spinothalamic pathway
2) dorsal column-medial lemniscal pathway
112
The primary somatosensory cortex (S1) receives input from both the ______________________ pathway and the _____________________
dorsal column- medial lemniscal
spinothalamic pathway
113
S1 contains a _________________ of the body, in which the skin of the body maps onto the surface of S1 in a systematic way
somatotopic map
114
The map is distorted in that areas of the body for which we need greater sensitivity (e.g., hands, mouth) have greater ______________ than for areas of the body for which we do not need as high sensitivity (e.g., back, legs)
representation
115
How is the suborganization of the somatosensory cortex?
S1 is divided into three regions
– Area 1 receives input from the mechanoreceptors
– Area 2 receives input from the proprioceptors
– Area 3a receives input from the proprioceptors and nociceptors
– Area 3b receives input from the nociceptors and mechanoreceptors
116
How can we distinguish our senses?
they have distinct pathways, and are kept separate. very organized
117
After the three regions of the somatosensory cortex, where do these areas send information to, to the secondary somatosensory cortex? (S2)
"What" channel or ventral system for identifying objects
"where" channel is in the posterior partietal cortex and premotor cortex in frontal lobe
