Neuro: Sensory Physiology Flashcards
(112 cards)
1
Q
define sensory receptor
A
neuronal specialization that allows transduction of physical stimuli into neural activity
2
Q
during transduction, a sensory receptor converts stimulus energy into ____
A
receptor potential
3
Q
a receptor potential is which type of potential?
A
graded
4
Q
if the the receptor potential reaches threshold for opening gated Na channels, a __ is generated
A
action potential
5
Q
information from sensory receptors is relayed to ___ by release and detection of __
A
interneurons ; neurotransmitters
6
Q
after the interneuron, information is processed and __ on its way to the __
A
integrated, cerebral cortex/subcortical area
7
Q
sensory receptors can be what 2 things?
A
- peripheral nerve endings of sensory neutron
2. specialized cells that synapse with sensory neutron
8
Q
t/f encapsulation of nerve ending changes the ability of the nerve ending to sense stimuli
A
true
9
Q
mechanoreceptors sense __
A
changes is stretch and pressure
10
Q
mechanoreceptors are located ___
A
skin, muscle, tendons, blood vessels
11
Q
thermoreceptors sense _
A
cold/warmth
12
Q
thermoreceptors are located __
A
skin
13
Q
photoreceptors sense __
A
light
14
Q
photoreceptors are located _
A
retina
15
Q
chemoreceptors are located
A
tongue and nose
16
Q
chemoreceptors sense _
A
certain chemical compounds
17
Q
nociceptors are located _
A
throughout the body
18
Q
nociceptors sense _
A
stimuli causing tissue damage
19
Q
what is the most unique class of receptors?
A
nociceptors
20
Q
nociceptors are polymodal, meaning __
A
they respond to a number of different stimuli
21
Q
t/f each receptor type is particular partial to one stimulus modality, but can be stimulated by other types if the stimulus is strong enough
A
true
22
Q
t/f all receptors of the primary sensory neurons respond tp the same stimulus modality
A
true
23
Q
define receptive field
A
area of body surface in which stimulus leads to activation of sensoryneuron
24
Q
stimulas location can be determined by neurons in the __ based on __
A
brain; which sensory receptors in the periphery have been activated
25
there is a ___ organization of sensory afferents in the cerebral cortex
topographical
26
acuity is based on receptive field __
size
27
what is acuity?
precision of stimulus location
28
the __ the size of the receptive field, the greater the acuity
smaller
29
the receptive field size is often determined by __
density of sensory neurons
30
what organization of sensory neurons would award the greater acuity?
high density of the same modality
31
how can acuity be acuity be measured?
2-point discrimination threshold
32
acuity is ___ by lateral inhibition
increased
33
what is lateral inhibition>
each sensory neutron can activate local inhibitory interneuron that inhibit nearby sensory neurons
34
receptive fields of adjacent sensory neurons of the same modality often __
overlap
35
when receptive fields overlap, a stimulus can activate both sensory neurons, but _
one more strongly than the other
36
where is the most effective location in a receptive field to apply stimulus?
center
37
stimulus intensity is encoded by what 2 things?
1. frequency of ap
| 2. # of sensory neurons activated
38
encoding stimulus intensity by frequency is called __
frequency coding
39
how can a weak stimulus manage to cause activation?
by landing in the middle of the receptive field
40
is it easier to find the site of stimulus for a week or string stimulus? why?
weak; because only sensory neutron that was directly applied will activate, weaker requires higher acuity because it can only activate one sensory neutron
41
what is the concept of adaption?
sensory receptors decrease sensitivity to stimulus of constant strength
42
in adaption, the frequency of ___ decreases
action potentials
43
sensory receptors can be either __ or __ adapting
slow/rapidly
44
rapidly adapting receptors are also called __
phasic receptors
45
slowly adapting receptors are also called _
tonic receptors
46
phasic receptors sgnal __
changes in stimulus intensity, either just onset or onset/offset
47
tonic receptors signal __
continued pressence of stimulus
48
in polyneuronal pathways, sensory neurons synapse onto __ neurons in the __ or __
second order ; brainstem and spinal cord
49
most sensory pathways ___
decussate (cross midline of the body)
50
stimulus on the right side of the body is processed in the __ side of the brain
left
51
what is converence>
higher order neutron receives inputs from multiple lower order neurons
52
what is divergence>
lower order neutron gives info to multiple higher order neurons
53
convergence and divergence allow for sensory ___
processing
54
what are labeled lines>
pathways dedicated to a specific stimulus modality
55
labelled lines carry ___ information to the ___ via the___
perceptive; cerebral cortex, thalamus
56
multimodal pathways oft have targets in the __ and often carry information on __, __ and _
subcortical area; pain, itch, temperature
57
neurons in the primary sensory cortex project into ___ areas for multimodal processing
associational cortical areas
58
in multimodal processing dome of the information targets subcortical areas that are responsible for __, __ and __
reflexes, arousal, and attention
59
what are the 6 types of somatosensory receptors on the body surface?
1. meissner's corpuscles
2. hair plexus
3. merkel's disks
4. Ruffini's corpuscles
5. pacinian corpuscles
6. free nerve endings
60
what is the modality of mess. corpuscles?
tough and dynamic pressure
61
where are mess corpuscles located?
glabrous skin (without hair)
62
what is the threshold for activation of mess corpuscles?
low
63
what is the modality of hair plexus?
touch dynamic pressure,
64
where are hair plexus located.
associated with hair follicles
65
what is the threshold for hair plexus?
low
66
what is the adaption type for mess corpuscles?
rapid
67
mess corpuscles are encapsulated by __ and located where in the skin
collagenous matrix; upper layer of the debris
68
how to hair plexi associate with hair follicles?
wrapping around them
69
ruffinis corpuscles are often located above __
joints
70
mechanoreceptors contain mechanically gated ion channels that mostly conduct __ and __ions
ca and na
71
deformation of ___ causes ion channel oping in mechanioreceprors
plasma membrane
72
how does encapsulation connective tissue influence adaption>
capsule elastically rebounds despite sustained stimulus, closing ion channels
73
thermoreceptors are what receptor type?
free nerve ending
74
thermoreceptors respond to temperature between __ and __
10 and 45
75
thermoreceptors contain __ channels that allow influx of ca and na
transient receptor potential
76
cold receptors can also be activated by what chemical compounds>
menthol
77
heat receptors can also be activated by what chemical compund>
camphor
78
what are the 3 types of nocireceptors?
1. mechanical
2. temp
3. polymodal
79
mechanical nocireceptor respond to
intense mechanical stimuli
80
thermal nocireceptors respond to __
temperature outside of 0-45 range
81
polymodal nocireceptors respond to _
intense mechanical and thermal stimuli, as well as chemicals released in tissues, such as histamine, prostaglandins, bradykinin and H+
82
mechanical and thermal nocireceptors are __ conducting via ___ fibres
fast; myelinated A sigma
83
polymodal nocireceptors are ___ conducting via __ fibres
slow; unmyelinated C
84
what is capsaicin?
chemical in chilli peppers that activates thermal nocireceptors
85
what causes referred pain?
projections of nocireceptors in skin and skeletal muscles and internal organs often converge onto the same second order neurons, causing somatic and visceral pain to be indistinguishable
86
give an example of referred pain
a myocardial infarction is felt as pain in left arm
87
what is hyperalgesia?
increased sensitivity of nocireceptors to pain
88
what causes hyperalgesia?
inflammation caused by the immune system
89
hyperalgesia is usually due to ___ sensitization
peripheral
90
what types of drugs can act as analgesics by preventing sensitization of nocireceptors?
anti-inflammatory, such as COX inhibitors
91
what is allodynia?
after an injury, perception of mechanical stimuli as painful
92
allodynia is due to __ sensitization
central
93
the central sensitization of allodynia is caused by
increased excitability of second-order neurons in the spinal cord
94
what is the endogenous analgesic system?
activation of certain brain centres (periductl grey, raphe Magnus) leading to suppression of pain
95
how does the endogenous analgesic system work?
descending pathways (midbrain to local inhibitory interneurons) suppress synaptic transmission from nocireceptors
96
what does the endogenous analgesic system release ?
opioids
97
opioid receptors are expressed on __ and __
nocireceptors and second-order nocioreceptive neurons
98
what is the premise of gate control of pain?
mechanical / temperature stimuli applied to a body area experiencing nocireceptive stimulus can reduce pain sensations
99
what is the proposed mechanism of gate control of pain?
mechanoreceptors and thermoreceptors activate local inhibitory interneurons that prevents release of NT (glutamate) that would cause pain sensation
100
the dorsal column pathway is a ___ pathway type
labelled line
101
the dorsal column pathway is also called the __
medial lemniscus
102
the dorsal column pathway conveys information of __, __, __ and ___
touch, pressure, vibration, and proprioception
103
what is proprioception?
sensory information from muscles, tendons and joints
104
describe the steps of the dorsal column pathways
primary sensory neuron to second order sensory neutron in brainstem to third order in thalamus to neurons in the primary sensory cortex
105
the dorsal column pathway decussates at the level of the __
brain stem (medulla)
106
the anterolateral pathway is also called the ___
spinothalamic pathway
107
the anterolateral pathway conveys information of ___, __ and __
temperature, pain, itch
108
describe the steps of the anterlateral pathway
primary sensory neuron to second order spinal cord neutron to third order thalamus neuron to primary sensory cortex
109
the anterolateral pathway decussates at the level of the
spinal cord
110
describe divergence in the anterolateral pathway
second order neutron also synapses onto neurons in the reticular formation(brain stem)
111
what is the impact of divergence in the anterolateral pathway?
alertness and arousal
112
t/f the anterolateral and dorsal pathways use the same thalamic neurons
fasle
