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NS-1 > Sensory Physiology > Flashcards

Sensory Physiology Flashcards

1
Q

What do Aalpha afferent neurons do?

A

large and fast

supply primary muscle spindles, golgi tendon organs

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2
Q

What do Abeta afferent fibers do?

A

secondary muscle spindles

skin mechanoreceptors

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3
Q

What do Aa motor fibers supply?

A

extrafusal sk m fibers

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4
Q

What do Agamma fibers supply?

A

intrafusal fibers

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5
Q

What do B motor fibers supply?

A

preganglionic autonomic fibers

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6
Q

What do c motor fibers supply?

A

postganglionic autonomic fibers

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7
Q

What is a generator potential and how does it vary?

A

somatosensory’s response to a stimulus

small with weak stim

strong stim –> large generator potential –> action potential

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8
Q

What is the significance of the thalamus in sensory systems?

A

info from all sensory systems except olfactory are relayed through the thalamus on way to cerebral cortex

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9
Q

What is convergence?

A

branches of 2 different primary afferents synapse on one secondary

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10
Q

What is divergence?

A

one primary neuron has 2 branches that synapse on 2 different secondaries

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11
Q

What are the 2 ways to get a strong stimulus?

A

all branches of one afferent or branches from multiple afferents converging

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12
Q

How do the number of active receptors change with intensity of stimulus?

A

increase in number w/ intensity

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13
Q

What is receptor adaptation?

A

when a stimulus persists unchanged for several min w/out change in position or amplitude –> neural response diminishes and sensation is lost

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14
Q

What are slow adapting and rapidly adapting receptors?

A

slow adapting: responde to prolonged and constant stim

rapidly adapting: only active at beginning or end of stimulus - when intensity increases or decreases

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15
Q

What are the rapidly adapting receptors and what they sense?

A

meissner corpuslce - tap, flutter

hair follicle receptor (can also be SA) - motion, direction

pacinian corpuscle - vibration

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16
Q

What are the slowly adapting receptors and what they sense?

A

hair follicle (can also be RA) - motion, direction

merkel disk - touch, pressure

ruffini corpuscle - skin stretch

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17
Q

What is the relationship btw tactile and acuity and receptive fields

A

acuity highest in smallest fields (lips)

acuity lowest in largest fields (back)

18
Q

What is the relationship btw convergence and tactile acuity?

A

more convergence –> less acuity

19
Q

What is pre-synaptic inhibition?

A

powerful form of inhibitory control

diminished excitatory signal: GABA –> Cl influx –> hyperpolarization –> less NT release

20
Q

How does presynaptic inhibition help you?

A

helps the brain not get overwhelmed –> can localize signal betters

21
Q

Are somatotopic maps fixed?

A

no

continual imput can magnify its map

restricted input decreases part of cortex devoted to that region

22
Q

What layers of the cortex are enlarged in sensory cortexes?

A

3 and 4 –> main site of axons from the thalamus

23
Q

How are neurons arranged in regard to depth?

A

neurons stacked above and below are very similar

columns side by side are different (explains homunculus) - usually same part of body, but different sensory modality

24
Q

Where is the primary somatosensory cortex

A

post-central gyrus

first stop for most cutaneous senses

25
Q

Where is the secondary somatosensory cortex?

A

in wal of sylvian fissure

receives input from S1 –> compares btw objects, diff tactile sensations and det whether something becomes a memory

26
Q

What is the PTO?

A

parieto-temporal-occipital association cortex

input from multiple places –> high level interpretation of sensory inputs

27
Q

What does S1 send projections to?

A

back to subcortical structures

usually thalamus

descending axons > ascending

permits focusing activities

28
Q

What do cortico-cortico projections do?

A

est parallel paths of sensation

allows for simultaneous processing

can be ipsi or contra

29
Q

What are corticofugal signals?

A

cortex –> lower relay

controls intensity of sensory sensitivity

typically inhibitory

30
Q

What is the doctrine of specific nerve energies?

A

no matter where along the afferent path is stim, sensation will occur and will arise from origin of sensation

31
Q

What type of pain does Adelta encode?

A

quick pain

32
Q

What type of pain do C fibers encode?

A

slow pain

33
Q

What are the different modes of nociception?

A

thermal

mechanical

chemical

receptors can be polymodal

can be silent and then turned on

34
Q

What are the 2 types of free nerve endings?

A

peptidergic: express substance P, CGRP, responsive to NGF most visceral afferents, 1/2 of cutaneous afferents

non-peptidergic: no neuropeptides, responsive to GDNF, 1/2 of cutaneous afferents

35
Q

What are TRP receptors?

A

sense noxious stimuli

ligand-gated non-selective cation channels

activated in response to temp (menthol, capsaicin)

36
Q

What do C and Adelta use as NTs?

A

C = EAA and SP/CGRP

Adelta = EAA

37
Q

What is descending inhibition?

A

signals from higher brain that dampens pain input

PAG stim by opiates, EAA, and cannabinoids –> locus coeruleus and raphe nucleus –> 5HT and NE –> dorsal horn –> activate inh interneurons –> opiates –> reduction of SP from C fiber –> reduces nociception

38
Q

What is the gate control theory of pain?

A

C fiber to 2ndary neuron and also to interneuron that inhibits 2ndary neuron to reduce pain signals

w/ strong pain - C fiber releases glycine –> inhibits interneuron –> EAA to secondary nerve –> pain

Abeta fiber can also stimulate the interneuron at the same time –> inhibits secondary neuron

(like when you rub your finger when you smash it)

39
Q

What is sub-threshold inflammation?

A

not apparent on histology but still causes pain

bradykinin involved

40
Q

What parts of the cortex are important in processing pain?

A

S1 and S2 - localization

insular cortex - integrates all signals, damage causes asymbolia

41
Q

What does the amygdala do in pain?

A

emotional component

42
Q

What do the hypothalamus and medulla do in pain?

A

visceral input w/ autonomic nerves –> hypothalamus and medulla –> physio changes

NS-1 (50 decks)

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