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PHYSIOLOGY SEMESTER 2 > lecture 4,5 & 6 General Sensory Mechanisms > Flashcards

lecture 4,5 & 6 General Sensory Mechanisms Flashcards

1
Q

what do type of endings do mechanoreceptors include

A

both free and encapsulated endings receiving tactile sensibilities

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2
Q

what are included in expanded tip endings of mechanoreceptors

A

merkel’s discs

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3
Q

what are included in encapsulated endings of mechanoreceptors

A

meissner’s corpuscles
kraus’ corpuscles
pacinian corpuscles

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4
Q

what is an example of a spray endings in mechanoreceptors

A

ruffini’s corpuscles

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5
Q

what are mechanoreceptors involved in

A

hearing: sound receptors of cochlea
equilibrium: vestibular receptors
arterial pressure: baroreceptors

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6
Q

define nocireceptors

A

free nerve endings responding to pain

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7
Q

define electromagnetic receptors

A

include rods and cones of the eye for vision

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8
Q

what do chemoreceptors sense

A

taste, smell, arterial oxygen, osmolarity, blood CO2, blood glucose, amino acids, and fatty acids

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9
Q

define differential sensitivity

A

each type of receptor is highly sensitive to one type of stimulus and is almost non responsive to other types

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10
Q

define modality

A

each of the principal types of sensation

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11
Q

define labeled line principle

A

specificity of nerve fibers for transmitting only one modality of sensation

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12
Q

what are the 4 mechanisms of stimulation for receptors

A

mechanical deformation,
application of a chemical,
temperature change,
electromagnetic radiation

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13
Q

what are characteristics of tonic receptors

A

slow adapting,
detect continuous stimulus strength,
transmit impulses as long as stimulus is present

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14
Q

what are types of tonic receptors

A

muscle spindles, golgi tendon organs, macula and vestibular receptors, baroreceptors, chemoreceptors

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15
Q

what are characteristics of phasic receptors

A

rapidly adapting,
do NOT transmit a continuous signal,
stimulated only when stimulus strength changes,
transmit information regarding rate of change

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16
Q

describe type A nerve fibers

A

large and medium sized myelinated fibers of spinal nerves

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17
Q

describe type C nerve fibers

A

small, unmyelinated fibers,
conduct signals at low velocity,
make up more than half of all sensory fibers in most peripheral nerves and all postganglionic autonomic fibers

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18
Q

what type of nerve fibers are in all postganglionic autonomic fibers

A

type C

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19
Q

describe group 1a nerve fibers

A

fibers from annulospiral endings of muscle spindles

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20
Q

describe group 1b nerve fibers

A

fibers from golgi tendon organs

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21
Q

describe group II nerve fibers

A

from cutaneous tactile receptors and flower-spray

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22
Q

describe group III nerve fibers

A

carry temperature, crude touch and pricking pain

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23
Q

describe group IV nerve fibers

A

carry pain, itch, temperature and crude touch

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24
Q

what group of nerve fibers is not Type A

A

group IV

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25
Q

define receptor field

A

in spatial summation, the entire cluster of nerve endings from one pain fiber covers this area of skin

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26
Q

define stimulatory field of neuronal pool

A

neuronal area within the pool stimulated by each incoming nerve fibers

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27
Q

where do the terminals of the stimulatory field of a neuronal pool lie

A

lie on the nearest neuron it its field

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28
Q

define discharge zone of neuronal pool

A

includes all the output fibers stimulated by the incoming fiber

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29
Q

describe diverging neuronal pathways

A
  • may result in amplification of initial signal

* may allow transmission of original signal to separate areas

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30
Q

describe converging neuronal pathways

A
  • multiple input fibers converge onto a single output neuron

* input fibers may be from a single source or from multiple separate sources

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31
Q

what are reverberatory circuits caused by

A

positive feedback within neuron circuit

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32
Q

define reverberatory circuits

A

also called oscillatory circuits: a circuit once stimulated that may discharge repetitively for a long time

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33
Q

define somatic senses

A

collect sensory info from all over the body

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34
Q

what are the types of somatic senses

A

mechanoreceptive, thermoreceptive, pain

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35
Q

define special senses

A

vision, hearing, smell, taste, and equilibrium

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36
Q

where do exteroreceptive sensations come from

A

from the surface of the body

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37
Q

what does proprioceptive sensations refer to

A

physical state of the body: position sensations, muscle and tendon sensations, pressure sensations, equilibrium

38
Q

define deep sensations

A

deep pressure, pain and vibrations

39
Q

define mechanoreceptive somatic senses

A

include both tactile and position senses that are stimulated by mechanical displacement of some tissue of the body

40
Q

describe primary sensory neurons

A

from external receptors,
travel through dorsal roots of spinal cord,
synapse with secondary neurons

41
Q

describe secondary neurons

A

make up tracts in spinal cord and brainstem,
usually terminate in thalamus,
synapse with tertiary neurons

42
Q

describe tertiary neurons

A

from thalamus to primary sensory cortex,

travel through internal capsule

43
Q

what ascending pathways are for conscious perception

A

spinothalamic and medial lemniscal

44
Q

what ascending pathways are for unconscious perception

A

spinocerebellar,
spino-olivary,
spinotectal,
spinoreticular

45
Q

what do lateral spinothalamic tracts carry

A

pain and temperature

46
Q

where doe primary fibers of lateral spinothalamic tract ascend/descend

A

1-2 spinal cord segments before synapses with secondary fibers

47
Q

where do the secondary axons of the lateral spinothalamic tract decussate

A

through anterior gray and white commissures

48
Q

what do the secondary fiber collateral that project to reticular formation (lateral spinothalamic tract) stimulate

A

wakefulness and consciousness

49
Q

what do tertiary fibers of the lateral spinothalamic tract form

A

part of internal capsule

50
Q

what sensations does the anterior spinothalamic tract carry

A

light touch (crude touch), pressure, tickle, itch

51
Q

where do the primary neurons of the anterior spinothalamic tract ascend

A

8-10 spinal cord segments before synapses with secondary neurons

52
Q

where do tertiary fibers of the anterior spinothalamic tract ascend

A

through internal capsule to primary sensory cortex

53
Q

what sensations does the medial lemniscus system carry

A

for 2 point sensation (fine touch), pressure and vibration

54
Q

where do the primary fibers synapse with secondary neurons in the medial meniscus system

A

medulla

55
Q

where do fibers of fasciculus gracilis synapse in

A

nucleus gracilis

56
Q

what do the fibers of fasciculus gracilis synapse in nucleus gracilis convey (medial lemniscus system)

A

convey sensations from below mid thoracic level

57
Q

what do the fibers of fasciculus cuneatus synapse in nucleus cuneatus convey

A

sensations from above mid thoracic level; also conveys proprioceptive sensations from arms to cerebellum

58
Q

what is the primary somatosensory area made up of

A

Brodmann’s areas 1, 2, and 3

59
Q

what is the somatosensory association area made up of

A

Brodmann’s areas 5 and 7

60
Q

where does somatosensory area 2 receive signals from

A

brain stem, transmitted upward from both sides of the body, secondarily from somatosensory area 1, and other sensory areas of the body (including visual and auditory)

61
Q

what do layers 1 and 2 of the somatosensory cortex do

A

receive input signals from lower brain centers

62
Q

what do layers 2 and 3 of the somatosensory cortex do

A

send info through corpus callosum to opposite hemisphere

63
Q

what do layers 5 and 6 of the somatosensory cortex do

A

large neurons in layer 5 project to distant areas (basal nuclei, brain stem, spinal cord) and axons from layer 6 project to thalamus

64
Q

where do primary sensory neurons originate

A

from peripheral receptors

65
Q

how do primary sensory neurons enter the spinal cord

A

via dorsal roots of spinal (cranial) nerves

66
Q

where do primary sensory neurons synapse with secondary neurons

A

spinal cord

67
Q

where do secondary sensory neurons synapse with tertiary sensory neurons

A

thalamus

68
Q

why is lateral inhibition important for 2 point discrimination touch

A

important in blocking the lateral spread of excitatory signals, thereby increasing the degree of contrast in the cerebral cortex

69
Q

where does lateral inhibition occur

A

(at each synaptic level): dorsal column nuclei, ventrobasal nuclei of thalamus, somatosensory cortex

70
Q

where do axons from the lower limbs travel (for dorsal column-medial lemniscal pathway)

A

travel in the medial portions of the 2 dorsal columns in areas called fasciculus gracilis

71
Q

where do the axons from the upper limbs travel (for dorsal column-medial lemniscal pathway)

A

in the lateral portions of the 2 dorsal columns (each of these areas is called fasciculus cuneatus)

72
Q

where do the axons in the fasciculus gracilis synapse in the lower medulla?

A

nucleus gracilis

73
Q

where do the axons in the fasciculus cuneatus synapse in the lower medulla?

A

nucleus cuneatus

74
Q

what paired tracts do the secondary neurons travel through the brain stem as in the dorsal column-medial lemniscal pathway

A

medial lemniscus

75
Q

what type of fibers typically carry fast pain

A

type A delta

76
Q

where do pain fibers of fast pain typically terminate

A

lamina A (lamina marginalis) of the dorsal horns of the spinal cord

77
Q

where do the pain fibers of slow pain typically terminate

A

layers 2 and 3 (substantial gelatinosa) of the dorsal horns of the spinal cord

78
Q

what type of fibers is slow chronic pain typically carried on

A

C type fibers

79
Q

what tract do the fast pain fibers make up

A

neospinaothalamic tracts

80
Q

what tract do the slow pain fibers make up

A

paleospinothalamic

81
Q

what neurotransmitter do fast pain fibers (type A-dalta) use

A

glutamate

82
Q

what neurotransmitter do type C fibers use

A

glutamate and substance P

83
Q

when does brown-sequard syndrome occur

A

when there is a hemisection of the spinal cord

84
Q

what are the 3 components of the analgesia system

A
  • periaquaductal gray and periventricular regions of the brainstem and 3rd ventricle
  • raphe magnus nucleus and reticular nuclei in medulla
  • pain inhibitory complex in dorsal horns of spinal cords
85
Q

what are the 3 types of receptors that discriminate thermal gradation

A

cold, warmth, pain

86
Q

describe warmth nerve endings

A

free nerve endings and mainly transmitted over C-type fibers

87
Q

describe cold receptors

A
  • 3-10 times as numerous as warm nerve receptors;

* small type A-delta myelinated endings

88
Q

when does referred pain occur

A

when visceral pain fibers are stimulated and stimulate some of the pain fibers that conduct pain signals from the skin

89
Q

how is all visceral pain from the thoracic and abdominal cavities tranmissted

A

via type C pain fibers

90
Q

what are headaches the result of

A

pain referred to the surface of the head from deep head structures

PHYSIOLOGY SEMESTER 2 (20 decks)

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