How Do We Touch & Feel Pain? Flashcards

1
Q

transduction

A

conversion of one signal-> NT binds receptor-> EPSP

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2
Q

somatosensory system transduces

A

mechanical stimulation of skin
injury to skin
changes in temperature

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3
Q

mechanosensation

A

touch, pressure, vibration

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4
Q

nociception

A

pain, temperature

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5
Q

sensory structures

A

epidermis
dermis
hypodermis

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6
Q

epidermis

A

free nerve endings

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7
Q

free nerve endings

A

detect pain & temperature

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8
Q

receptors in the dermis

A

Merkel’s disc
Meissner’s corpuscle
Hair follicle receptor

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9
Q

Merkel’s disc

A

fine (discriminative) touch

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10
Q

Meissner’s corpuscle

A

light touch

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11
Q

hair follicle receptor

A

touch

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12
Q

hypodermis

A

Pacinian corpuscle
Ruffini’s ending

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13
Q

Pacinian corpuscle

A

vibration, pressure

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14
Q

Ruffini’s ending

A

stretch
ex. bump on your head- can feel your skin stretching

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15
Q

The same cell can detect vibrations and pain?
True or false

A

False
nociceptors, free nerve endings

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16
Q

detecting pressure and vibration

A

Pacinian corpuscle

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17
Q

cell bodies in Pacinian corpuscle located in:

A

dorsal root ganglia

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18
Q

Pacinian cell has one axon that splits into 2

A

one end leads to corpuscle in skin
other end into the dorsal spinal cord

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19
Q

steps of transduction in Pacinian corpuscles

A
  1. mechanical stimulus stretches corpuscle membrane
  2. Na+ channels open and corpuscle depolarizes (called receptor potential)
  3. if threshold potential reached- an action potential is generated
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20
Q

What is a receptor potential most similar to?
A. Action potential
B. Postsynaptic potential

A

B. Postsynaptic potential

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21
Q

What distinguishes different somatosensory receptor cells?

A

adaptation
receptive field

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22
Q

How do we distinguish between stimuli? (strength, time period)?

A
  • number of neurons activated
  • number of action potentials
  • pattern of action potentials
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23
Q

a neuron can continue to fire action potentials or can

A

adapt

24
Q

adaptation

A

progressive loss of response to stimulus
allows detection of change

25
Q

fast-adapting receptors

A

Pacinian corpuscle
Meissner’s corpuscle
can tell when it changes- will change action potential

26
Q

slow-adapting receptors

A

Merkel’s discs
Ruffini’s ending
is activated for quite a while

27
Q

receptive field

A

is area where a stimulus will alter a single neuron’s activity

28
Q

each receptive field differs in

A

size, shape and response to type of stimulation

29
Q

each type of mechanosensation and receptive fields covers

A

entire expanse of skin
can have multiple different neuron types because the receptive fields overlap

30
Q

Which receptor cell will be most helpful in reading Braille letters?
A. Meissner’s corpuscle
B. Merkel’s discs
C. Ruffini’s ending
D. Pacinian corpuscle

A

B. Merkel’s discs

31
Q

dorsal column system pathway

A

spinal cord->brainstem->thalamus->primary sensory cortical areas

32
Q

dorsal column system steps

A
  1. somatosensory receptor cells send axons into spinal cord
  2. join the dorsal column and synapse in dorsal column nuclei in medulla
  3. medulla axons cross midline and synapse in thalamus- left medulla to right medulla, vice versa
  4. thalamic cells relay somatosensory cortex in the parietal lobe
33
Q

innervation of a Pacinian corpuscle

A

dorsal root ganglion
unipolar cell

34
Q

dermatomes

A

touch is mapped by the dermatome and which place the touch is placed
cervical- 8
thoracic- 12
lumbar- 5
sacral- 5
inputs from dermatomes are segregated at all levels

35
Q

topographic maps

A

primary somatosensory cortex (SI) has homunculus map
most sensory places have most representation

36
Q

somatosensory loss

A

if youre not using a somatosensory or body part or sense might end up getting reorganized and used for something else
ex. amputations

37
Q

What is the purpose of pain?

A
  1. acute pain causes us to move to prevent further injury
  2. chronic pain may cause us to rest and heal
  3. pain can be a social cue for others (babies cry after they call over)
38
Q

pain generation

A

when mechanical pressure on the skin causes tissue damage
bleeding, swelling, tissue damage
high temperature, burns
chemical damage

39
Q

free nerve endings detect

A

pain
nociceptors=pain receptors

40
Q

nociception pathway

A

damaged cells release substances that excite free nerve endings

41
Q

substances that inhibit the synthesis of prostaglandins

A

aspirin, ibuprofen, and acetominophen

42
Q

cold/hot sensing fibers

A

C fibers
Ab fibers
Capsaicin
menthol

43
Q

C fibers

A

unmyelinated
warm and cold stimulus free nerve endings

44
Q

Ab fibers

A

myelinated- pain information flies up to spinal cord
respond to really hot stimuli
important for reflex

45
Q

CMR1 receptors

A

can be stimulated by cold stimulus
menthol

46
Q

TRPV1 receptors

A

capsaicin
can be stimulated by warm stimulus

47
Q

damaged cells release these substances that excite free nerve endings

A

serotonin
K+
prostaglandins
leukotrienes

48
Q

action potential can also excite other blood vessels and other cells to produce

A

inflammation

49
Q

action potential in pain fiber releases

A

glutamate and substance P (neuromodulator) in the dorsal horn of spinal cord
the dorsal horn cells then sends the information across the midline and up to the thalamus

50
Q

axons within the spinothalamic tract synapse in

A

thalamus

51
Q

thalamic neurons send axons to

A

somatosensory cortex

52
Q

When you eat a chili pepper, why does it take a few seconds for
you to feel the heat?
A. Because C fibers are myelinated
B. Because C fibers are unmyelinated
C. Because A-delta fibers are myelinated
D. Because A-delta fibers are unmyelinated

A

B. Because C fibers are unmyelinated

53
Q

neuropathic/chronic pain

A

may be due to inappropriate signaling of pain by neurons
even though pain has gone away- still signals free nerve endings
free fibers are more sensitive and generate action potentials more easily

54
Q

microglia at injury site

A

release chemicals

55
Q

dorsal horn neurons can become

A

hyperexcitable, leading to chronic pain

56
Q

phantom limb pain

A

feels like neuropathic pain
misinterpreted signals
cortical reorganization does not match the dermatome
signals are coming in distorted causing to feel pain in the missing limb