Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PHGY 209 > CNS/sensory 3 - somatosensory > Flashcards

CNS/sensory 3 - somatosensory Flashcards

1
Q

what is somatic - bodily sensation mediated by

A

several types of receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

describe the types of receptors - what makes them different

A

specialized end organss that wrap around afferent in skin
allows you to be sensitive and encode to specific types of energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

describe touch

A

mehcanoreceptors with specialized end organs that surround nerve terminal
end organs allow only selective info to activate nerve terminal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what mediates touch at superficial layers

A

meissner’s corpuscle
merkel disk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what mediates touch at deep layers

A

pacinian corpuscle
ruffini endings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

describe meissner’s corpuscle

A

fluid filled structure enclosing nerve terminal
rapidly adapting
light stroking and fluttering (sensitive to light or weak stimulus energy and since rapidly adapting = sensitive to changes that occur via strokes or light vibrations)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

describe merkel disk

A

small epithelial cells surround nerve terminal
slowly adapting
pressure and texture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

describe pacinian corpuscle

A

large concentric capsules of connective tissue surround nerve terminal
rapidly adapting
strong vibrations (deep in skin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

describe ruffini endings

A

nerve endings wrap around spindle like structure
slowly adapting
Stretch and bending of skin - shape of object - can know this as you grab and touch object

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

describe proprioception

A

muscle spindles provide sense of static position and movement of limbs and body
part of somatosensory but closely related to motor control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what are mechanoreceptors activated by

A

stretching of cytoskeletal strands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

describe activation of mechanoreceptors

A

mechanical deformation causes membrane of afferent to be deformed and put pressure or tension on cytoskeletal strands
they pull = open ion channels = mechanical transduction process
mechanical opening of ion channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

describe temperature

A

thermoreceptors are free nerve endings
contain ion channels
Respond to different temperature ranges
can also open via chemical substances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

describe cold afferents

A

0-35 degrees c
Activated by menthol = casue ion channels to open, feels cold but skin not actually cold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

describe warm afferents

A

30-50 degrees c
Activated by capsaicin = chemical compound in chile peppers, can activate warm afferents, if too much = pain
activated by ethanol = makes you feel warm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what do extreme temperatures do

A

activate pain receptors
temps out of ranges = pain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

describe pain

A

nociceptors are free nerve endings
Contain ion channels that open in response to intense mechanical deformation, excessive temperature or chemicals - things that will/are producing tissue damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

pain afferents are

A

high modulated
enhanced - bottom up and suppressed - top down (can shut off pain)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

descrive visceral pain receptors

A

activated by inflammation
inside body = respond to intense mechanical problems inside you and you feel pain

20
Q

what are nociceptors enhanced by

A

many mediators

21
Q

give basic pathway of nociceptors

A

1=tissue damage
2=activate nociceptors - fire aps
3=substance p released in spinal cord (neurotransmitter released to 2nd order neurons)
4= info goes to brain = pain
5 = enhancement of surrounding nociceptors by injured tissue and afferent feedback onto mast cells
6 = dilation of blood vessels, red, inflamed, pain

22
Q

what is hyperalgesia

A

increased sensitivity to pain after injury = bottom up
happening by itself - out of your control - tells you damage is there and not to use it

23
Q

what causes hyperalgesia

A

release of substance p onto mast cells (release histamine) and dilates blood vessels
also cells rupture and release all kinds of stuff - bradykinin, 5-ht, prostaglandin, k+

24
Q

how is somatosensory info sent to brain - 2 ways

A

dorsal columns
anterolateral pathway

25
Q

what dorsal columns send info about

A

touch and proprioception

26
Q

describe dorsal columns pathway

A

light feather stimulus –> spinal nerve –> dorsal root ganglion –> enters dorsal root and goes up –> dorsal columns –> enters brainstem –> synapse on 2nd order neurons and crosses midline –> medial lemniscus (contralateral touch and proprio) –> thalamus –> somatosensory corext

27
Q

what does ipsilateral mean

A

same side
dorsal columns carry ipsilateral touch and proprio

28
Q

what does contralateral mean

A

opposite side of midline

29
Q

what do anterolateral pathways send info about

A

temp and pain

30
Q

describe anterolateral pathway

A

finger on candle –> spinal nerve –> dorsal root ganglion –> dorsal horn –> anterolateral column (spinothalamic), synapse on 2nd order neurons in segment and cross over around midline –> brainstem –> branches into reticular formation –> thalamus –> somatosensory cortex *receives contralateral info

31
Q

where is lesion if ipsilateral loss of touch and proprioception at and below the level of the lesion

A

dorsal column lesioned, just one = ipsilateral touch and proprio

32
Q

if left cervical dorsal columns lesioned - name symptoms

A

Loss of touch and proprioception perception starting at the left hand and proceeding down to the toes.
Touch and proprioception are normal on the right side of the body.
Pain and temperature perception are normal on both sides of the body.

33
Q

where is lesion if bilateral loss of touch and proprioception from bellybutton down to toes but pain and temp intact

A

both dorsal columns

34
Q

what happens in lesion right in middle of gray matter of spinal segment

A

Bilateral loss of pain and temperature in a thin strip at the level of my lower chest.
Touch and proprioception are intact.

35
Q

describe brown sequard lesion

A

loss of touch, proprioception, temp and pain on left side
loss of touch and proprioception and motor on left side
loss of temp and pain on right side
lesions =
damage anterolateral columns - temp and pain from contralateral side
Damage dorsal column = loss of touch and proprio at level of lesion and below on ipsilateral side
damage single spinal segment = dorsal root is blocked so all somatosensory info blocked on ipsilateral side
left hemisection of spinal cord = where lesions are

36
Q

describe somatosensory cortex

A

contralateral representation
has organized layout

37
Q

what is order from lateral to medial

A

head
arms
legs

38
Q

what has highest acuity

A

hands then head - face and lips
low acuity = back

39
Q

what does somatosensory cortex drawing show

A

how much area is taken up by portion of body is porprotional to number of afferents that innervate area
small receptive fields = many afferent = high acuity

40
Q

what happens if contralateral loss of all somatosensation corresponding to head

A

damage to lateral somatosensory cortex

41
Q

what is referred pain

A

visceral and somatic pain afferents commonly synapse on same neurons in spinal cord
perception of pain = on skin, but activation of pain afferent = inside body
synapse on same 2nd order neuron so body does not know where it comes from
brain usually assigns to skin
heart attacks commonly produce pain in left arm

42
Q

why does referred pain happen

A

labeled line code - brain knows modality and every location of afferents
has label
EXCEPT PAIN

43
Q

what do descending pathways do

A

regulate nociceptive information
top down

44
Q

describe descending pathways

A

periaqueductal gray matter (midbrain)
reticular formation (medulla)
dorsolateral funiculus - activates descending pathway
synapse on pain afferents = shut down pain, and substance p being released
analgesia

45
Q

how can pain be reduced

A

presynaptic inhibition

46
Q

describe reduction of pain through presynaptic inhibition

A

descending pathways from brainstem = release opiate neurotransmitters - presynaptic inhibition and inhibits substance p
same effect as morphine - site of action of opiates

PHGY 209 (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions