How Do We Touch & Feel Pain?

Question 1

transduction

Answer 1

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

Question 2

somatosensory system transduces

Answer 2

mechanical stimulation of skin
injury to skin
changes in temperature

Question 3

mechanosensation

Answer 3

touch, pressure, vibration

Question 4

nociception

Answer 4

pain, temperature

Question 5

sensory structures

Answer 5

epidermis
dermis
hypodermis

Question 6

epidermis

Answer 6

free nerve endings

Question 7

free nerve endings

Answer 7

detect pain & temperature

Question 8

receptors in the dermis

Answer 8

Merkel’s disc
Meissner’s corpuscle
Hair follicle receptor

Question 9

Merkel’s disc

Answer 9

fine (discriminative) touch

Question 10

Meissner’s corpuscle

Answer 10

light touch

Question 11

hair follicle receptor

Answer 11

touch

Question 12

hypodermis

Answer 12

Pacinian corpuscle
Ruffini’s ending

Question 13

Pacinian corpuscle

Answer 13

vibration, pressure

Question 14

Ruffini’s ending

Answer 14

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

Question 15

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

Answer 15

False
nociceptors, free nerve endings

Question 16

detecting pressure and vibration

Answer 16

Pacinian corpuscle

Question 17

cell bodies in Pacinian corpuscle located in:

Answer 17

dorsal root ganglia

Question 18

Pacinian cell has one axon that splits into 2

Answer 18

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

Question 19

steps of transduction in Pacinian corpuscles

Answer 19

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

Question 20

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

Answer 20

B. Postsynaptic potential

Question 21

What distinguishes different somatosensory receptor cells?

Answer 21

adaptation
receptive field

Question 22

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

Answer 22

• number of neurons activated
• number of action potentials
• pattern of action potentials

Question 23

a neuron can continue to fire action potentials or can

Answer 23

adapt

Question 24

adaptation

Answer 24

progressive loss of response to stimulus
allows detection of change

Question 25

fast-adapting receptors

Answer 25

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

Question 26

slow-adapting receptors

Answer 26

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

Question 27

receptive field

Answer 27

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

Question 28

each receptive field differs in

Answer 28

size, shape and response to type of stimulation

Question 29

each type of mechanosensation and receptive fields covers

Answer 29

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

Question 30

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

Answer 30

B. Merkel's discs

Question 31

dorsal column system pathway

Answer 31

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

Question 32

dorsal column system steps

Answer 32

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

Question 33

innervation of a Pacinian corpuscle

Answer 33

dorsal root ganglion unipolar cell

Question 34

dermatomes

Answer 34

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

Question 35

topographic maps

Answer 35

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

Question 36

somatosensory loss

Answer 36

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

Question 37

What is the purpose of pain?

Answer 37

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)

Question 38

pain generation

Answer 38

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

Question 39

free nerve endings detect

Answer 39

pain nociceptors=pain receptors

Question 40

nociception pathway

Answer 40

damaged cells release substances that excite free nerve endings

Question 41

substances that inhibit the synthesis of prostaglandins

Answer 41

aspirin, ibuprofen, and acetominophen

Question 42

cold/hot sensing fibers

Answer 42

C fibers Ab fibers Capsaicin menthol

Question 43

C fibers

Answer 43

unmyelinated warm and cold stimulus free nerve endings

Question 44

Ab fibers

Answer 44

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

Question 45

CMR1 receptors

Answer 45

can be stimulated by cold stimulus menthol

Question 46

TRPV1 receptors

Answer 46

capsaicin can be stimulated by warm stimulus

Question 47

damaged cells release these substances that excite free nerve endings

Answer 47

serotonin K+ prostaglandins leukotrienes

Question 48

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

Answer 48

inflammation

Question 49

action potential in pain fiber releases

Answer 49

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

Question 50

axons within the spinothalamic tract synapse in

Answer 50

thalamus

Question 51

thalamic neurons send axons to

Answer 51

somatosensory cortex

Question 52

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

Answer 52

B. Because C fibers are unmyelinated

Question 53

neuropathic/chronic pain

Answer 53

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

Question 54

microglia at injury site

Answer 54

release chemicals

Question 55

dorsal horn neurons can become

Answer 55

hyperexcitable, leading to chronic pain

Question 56

phantom limb pain

Answer 56

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