Somatosensory Ascending Pathway - Part I Flashcards
(105 cards)
1
Q
How do the mechanoreceptors encode the characteristics of the stimuli?
A
different mechanoreceptors respond to limited different modalities of stimuli
2
Q
What is the concentration of mitochondria in the stimuli detection area?
A
high!
3
Q
What is a specialized nerve ending?
A
receptive area
4
Q
What is an example of a specialized cell or neuron ?
A
- visual pathway (i.e. rods)
- hair cells for hearing, vestibular functions
5
Q
What are the two layers of receptors?
A
- microscopic (bigger)
- macroscopic (very small)
6
Q
What do microscopic receptors detect?
A
energy
- molecules interactive with the stimulants/energy
7
Q
What are the characteristics of macroscopic receptors?
A
- high concentration of mitochondria in the stimuli detection area
- specialized nerve ending
- specialized cell or neuron
8
Q
What mechanoreceptor does blood pressure?
A
- carotid sinus
9
Q
What chemoreceptor does oxygen concentration of blood?
A
- carotid body
10
Q
What do mechanoreceptors detect?
A
fine touch, vibration, stretch, etc
11
Q
What kind of receptor is for A-beta?
A
mechanoreceptor
12
Q
What do chemoreceptors detect?
A
taste, smell, pH, O2, etc.
- i.e. carotid body for O2 concentration
13
Q
What do thermoreceptors detect?
A
cold to hot, FLAVOR OF FOOD
14
Q
What do nociceptors detect?
A
noxious stimuli, pain
15
Q
What is another sensory receptor not usually mentioned?
A
electromagnetic waves
- FISH, know how to swim home
16
Q
Where does conscious localization project to?
A
S1
17
Q
Is somatotopy maintained with conscious localization?
A
yes
18
Q
What maintains the somatotopy?
A
- dorsal column (fine touch, vibration)
- lateral spinothalamic tract (sharp p!)
19
Q
Where does unconscious localization project to?
A
subcortical structures
- reticular formation, cerebellum, etc.
20
Q
What are other special sensations?
A
taste, smell, vision, hearing, vestibular
21
Q
Do we need the somatotopy for taste?
A
no
- cannot remember all tastes all the time, tongue detects
22
Q
Do we need the somatotopy for smell?
A
No
- nasal cavities
23
Q
Do we need the somatotopy for vision?
A
NO, have retinotopy
- reason we know whats on left and right, image is projected on retina
24
Q
Do we need the somatotopy for hearing?
A
NO, have tonotopy
- composes sound into different frequency, projects to A1, integrates, and decodes meaning of sounds
25
Why is the vestibular sensation important?
- body in space, integrate info in cerebral cortex
- BALANCE
26
What is the intensity of receptor potential measured in?
AMPLITUDE
- changes in the intensity of the stimuli
27
What is the intensity of action potentials measured in?
FREQUENCY
- receptor potential above the threshold
28
How many AP can happen in 1 second?
- with higher receptor potential higher AP, can have few to 1000s
29
When does the receptor potential stop?
when stimuli stops
30
Do we still have a baseline AP without stimuli?
Yes
- if you want to rob a bank you dont turn off your car
- helps us be ready/prepared for next function
31
What are lagging effects?
persistence of vision
32
Where is sensory memory most prominent?
visual system
33
What is an example of a slowly adapting static stimuli?
smell
- weird food, stink, but adapt and "less stink"
34
What kind of stimuli are you slowly adapting receptors for?
static stimuli
35
What kind of stimuli are rapidly adapting receptors for?
dynamic stimuli
36
What kind of adaptor is for pulling hair CONSTANTLY?
Slow adapting, static stimuli
37
What kind of adaptor do motor function need?
fast adapting (FA)
38
Which ascending and descending tracts run in the lateral funiculus?
Descending
- lateral corticospinal tract
- rubrospinal tract
- medullary reticulospinal tract
Ascending
- lateral spinothalamic tract
39
How are receptors transducted?
- stimulants/energy as neurotransmitters
- on receptor cells or nerve endings
40
Where is the receptor area for transduction of receptors?
post-synaptic membrane
41
What kind of receptors are on the post-synaptic membrane?
- ionotropic receptor
- metabotropic receptor
42
What are the effects of transduction of receptors?
- Excitatory: EPSP, depolarization
- Inhibitory: IPSP, hyperpolarization
43
What kind of channel is in the trigger zone?
voltage-gated sodium channel
44
What can be receptor/receptive areas?
cell or specialized area of nerve endings
45
Where does peripheral process occur?
outside of CNS
- conduct along axons
- CNS: brain stem or spinal cord
46
What is an examplie of a trigger zone?
like in a hillock
47
What happens in a trigger zone?
- rock in lake, waves spread everywhere
- changes to initiate AP
- spreads out, receptor potential intensity decreases = dissipation
48
What happens in the central process?
SHORT
- axons arrive to soma
- in CNS
49
What should we know about the cauda eqina?
- LONG
- axons get myelin sheath from oligodendrocytes (sensory and motor)
- MS affects cauda equine myelin sheath (is destroyed)
50
What are the two types of skin?
- hairless/glaborous
- Hairy
51
What kind of receptors are free nerve endings?
unimodal and polymodal receptors
52
What are the layers of cutaneous innervators?
- free nerve endings (EVERYWHERE)
- Meissner corpuscle
- Merkel cell
- Ruffini corpuscle
- Pacinian corpsule
53
Where is hairless/glabrous skin found?
palm/sole/lip
54
What are free nerve endings in?
EVERY BODY PART
- epidermis
55
What are the 4 cutaneous mechanoreceptors?
1. Meissner corpuscle
2. Merkel cell
3. Ruffini corpuscle
4. Pacinian corpsule
56
What cutaneous receptors are unimodal?
- merkel cell
- Ruffini corpuscle
- Pacinian corpuscle
57
Where is hairy skin found?
EVERYWHERE but palm,lip, and sole
58
What kind of mechanoreceptor is not in hairy skin?
Meissner corpuscle
59
How many mechanoreceptors are in hairy skin?
still 4
60
Where are meissner corpuscles located?
Hairless skin only
61
What do meissner corpuscles detect?
flutter/vibration of small amplitude
62
What common sensation is done by the meissner corpuscles?
numbness/tingling
63
What do free nerve endings detect?
pain and crude touch
64
Why does a paper cut that does not draw blood still hurt?
free nerve endings in epidermis
- no blood vessels, but FNE = p!
65
What kind of pain fibers are in the free nerve endings?
C- fibers and A-delta
66
Are C-fibers myelinated?
NO = SLOW
67
Are A-delta fibers myelinated?
poorly myelinated, SLOW
68
What do merkel cells detect?
complex and fine touch, percieving edges and stereognosis
69
What is sterognosis?
know structure without seeing it using only feeling
- paper bag in NMSK
70
What is the function of hair follicle receptors?
fine touch and movement
- hairy skin only (duh)
- ex. cat whisker, detects movement
71
What do ruffini endings detect?
stretch sensation in skin
- somatic!
- A- beta (SA)
72
What do pacinian corpuscles detect?
various functions including vibration in skin (higher amplitude than meissner)
73
Where are pacinian corpuslce slocated?
strictly, not in skin; whole body
74
What is a receptive field?
area innervated by one single axonal terminal
75
What is unique about receptive fields?
smaller and more disciminative
76
Where are fine touch/2-point discrimination highest?
in fingers, lips, sole
77
Where are fine touch/2-point discrimination fields located?
around the glabrous/hairless skin
78
What kind of mechanoreceptors are for fine touch/2-point discrimination?
- UNIMODAL
* meissner corpuscle and Merkel Cell
79
When performing 2 point discrimination test, what are you testing?
Ability to differentiate two points in a receptive field
- Meissner
- Merkle
80
Which mechanoreceptors are in the glabrous/hairless skin?
- Meissner corpuscle
- Merkle cell
- Ruffini endings
- Pacinian corpuscle
81
What are the two types of skeletal muscle fibers?
- extrafusal
- intrafusal
82
What are extrafusal muscle cells innervated by?
alpha motor neuron
83
What do intrafusal muscle cells form?
muscle spindle
84
What innervates the muscle spindle?
gamma motor neuron
85
What are the two types of fibers in the muscle spindle?
nuclear bad and nuclear chain fibers
86
What are intrafusal cells innervated by simultaneously?
- sensory neurons
87
What type of sensory neurons innervate the intrafusal muscle cells?
- Type Ia (Aα)/ II (Aβ)
FAST, highly myelinated
88
What do the type Ia (Aα)/ II (Aβ) sensory neurons that innervate intrafusal muscle fibers detect?
proprioception and motor information
89
What sensory neurons innervate nuclear bag and chain fibers in the muscle spindle?
Type II (Aβ)
90
What are the mechanoreceptors for intrafusal muscle cells?
like ruffini endsings
91
What kind of translator is the muscle spindle?
MOTOR TO SENSORY
- translates motor functions to sensory feedback
92
Where is the golgi tendon organ located at?
musculotendinous junction
93
What is the golgi tendon organ innervated by?
Type Ib (Aα), Ruffini-like sensory neurons
- FAST
94
Why do we feel pain in muscles and tendons too?
free nerve endings
95
What kind of sensory neurons innervate the joint capsule?
Aα
96
What kind of nerve endings are in the joint capsule?
- ruffini-type endings
- pacinian-type endings
97
What does the joint capsule need to do?
detect change of body in space ASAP to maintain balance
98
What is the frequency of vibration for a tuning fork test?
128 Hz
99
What kind of nerve endings are being tested during a tuning fork test around joints?
pacinian type endings
100
What kind of channel is PIEZ02?
modality-gated sodium ion channel
101
What kind of terminals does PIEZ02 have?
both markel cell and axonal terminal
(A beta)
102
How does a PIEZ02 initiate an RP?
stretches open PIEZ02 and induces the receptor potential
- both merkel and axon terminal of A beta axons stretch above a specific amplitude of stimuli results in a resting potential
103
What should we know about the stimuli with PIEZ02?
- stimuli with different intensities
- Receptor potential to action potential
- weak can cause a receptor potential
- strong can make it above, initiate AP, open PIEZ02 channels and allow NA+ ions to flow in
104
What are the 2 types of free nerve endings in the skin?
1. c-fiber for diffuse pain; myelinated = fast
2. A-delta (Aδ) for first, sharp pain; poorly myelinated
105
Which nerves innervate the intrafusal muscle fibers?
γ motor neuron: Aβ
Ia: Aα
II: Aβ
Free nerve endings: Aδ and C-fiber
