Exam 2 Flashcards
(146 cards)
1
Q
How do sensory receptors respond to stimuli?
A
Different types of stimuli activate the opening and closing of ion channels
the type of stimuli that activates ion channels for a receptor is dependent on the physical structure of the receptor, the depth, and the surrounding structures
2
Q
Types of tactile cutaneous receptors (4)
A
Meissner corpuscles
Pacinian Corpuscles
Ruffini Corpuscles
Merkel Cells
3
Q
Merkel Cells
A
tactile cutaneous receptor
responds to light touch
gives information entire time stimuli is present
A-beta axon
4
Q
Meissner corpuscle
A
tactile cutaneous receptor
responds to light touch (more precise stimulation)
gives information when stimuli is present and when it leaves
A-beta axon
5
Q
Pacinian Corpuscle
A
tactile cutaneous receptor
responds to pressure and vibration
A-beta axon
6
Q
Ruffini Corpuscle
A
tactile cutaneous receptor
responds to stretch
A-beta axon
7
Q
Muscle Spindle
A
Wound around mm fiber
stretch receptor
A-alpha axon
8
Q
Golgi Tendon Organ
A
between mm cells
respond to force generated by mm contraction
A-alpha axon
9
Q
What does stimulus intensity depend on?
A
Action potential firing rate
higher rate for deep pressure
10
Q
Receptors that do proprioception
A
mm spindles
golgi tendon organs
joint receptors
11
Q
What does the somatosensory system system do
A
Body sensation
guidance of movement
influence behavioral state
protection from immediate and possible danger
12
Q
Label line for somatosensory stimuli
A
encoded in label line based on modality, location, intensity, and duration
13
Q
Two-point discrimination
A
ability to discriminate one point from two-points of indentation
varies across body
smaller 2-point discrimination means better tactile acuity
14
Q
Joint receptors
A
know less about these
may help with detecting pain or fatigue or injury
15
Q
somatosensory pathway divergence
A
diverges to cortex and brainstem (brainstem divergence is how somatosensory can influence behavioral state
16
Q
Nociceptors
A
C or A-omega axons
pain
mechanically, chemically, thermally gated ion channels
can be polymodal
free nn endings
innervate skin, muscoloskeletal, meningial, and visceral structures
17
Q
Pruriceptors
A
C or A-omega axons
itch
mechanically, chemically, thermally gated ion channels
can be polymodal
free nn endings
innervate skin, muscoloskeletal, meningial, and visceral structures
18
Q
Axon classification
A
axons have different diameters and descriptions
smaller diameter the less myelination and slower conduction rate
19
Q
Axon classification biggest to smallest
A
A-alpha A-beta A-gamma A-omega C
20
Q
Sensory pathway impairment
A
Loss of sensory awareness and discrimination
sensory ataxia is incoordination of movement results from impaired conscious perception of body position/movement
21
Q
Sensory cortical impairment
A
difficulties perceiving somatosensory input
loss of perception of objects
22
Q
Brodmann’s area 1 and 3b
A
Rapid/slow adaptation to cutaneous reception
23
Q
Brodmann’s area 2
A
Deep receptors and joint receptors
24
Q
Brodmanns’ area 3a
A
muscle receptors
25
Does CNS sensitize to pain or inhibit pain?
Both
26
Reduction of pain
Can be physical: gated theory
| Can be pharmocological
27
Pain
unpleasant sensory and emotional experience
results from nociceptor activity and perception
ex// under anesthesia, pain receptors still fire but there is not perception
28
Divergence of pain pathway
reticular formation: activates neuromodal system
Periaqueductal grey: activation of analgesic response
Hypothalamus: activates autonomic response
29
Allodynia
stimulus should not be perceived painful but it is
30
Central analgesic system
pain input to the cortex and PAG initiates descending inhibition of pain fibers via serotonin, endorphins, or norepinephrine
31
Serotonin and pain
Inhibits neurons in dorsal horn
32
Endorphins and pain
targets metabotropic receptor for inhibition effects
33
Gate theory
separate pathway activated by physical stimulation that activates A-beta fiber that synapses onto interneuron which releases enkephalin that inhibits second order neuron in spinothalamic pathway (ex// rubbing hurt thumb after getting hit with hammer)
-pain stimulation message gets turned off at the source
34
Is the spine strong or flexible and why?
strong and flexible to bear weight and move without collapsing
35
Filium terminale
anchors to coccyx, extension of pia mater
| anchors caudal SC so it stays straight
36
Dorsal roots
central axons of sensory neurons in dorsal root ganglion
37
Ventral roots
motor fibers exiting motor/sympathetic cells in ventral/lateral horns
38
What does the proportion of white to gray matter in the spinal cord mean?
Helps identify segment of spinal cord
some areas have more gray matter than others
Ex// cervial and lumbar enlargements
39
Spinal cord meninges
3 meningeal layers
dura only has meningeal later and not periostial layer
pia thickens to give off dentate ligament (filium terminae)
40
Dermatome
area of skin innervated by single spinal nerve
41
Describe the spinal cord's blood supply
anterior spinal artery and two posterolateral spinal arteries connected by corona artery all along length
form circle around SC
42
Which level does the spinal CORD end at?
around L2-L3
still nerves but no longer in cord
cauda equina
43
What are separate areas of cord marked by a pair of spinal nerves called?
Spinal segments
44
How many pairs of SC nerves are there?
31 (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal)
45
Organize roots, rootlets, and nerves
Dorsal rootlets -> dorsal root
Ventral rootlets-> ventral root
Ventral root + dorsal root-> spinal nerve
46
Myotome
mm innervated by a nerve root
| some mm innervated by multiple segments
47
What is a key mm?
can test these mm to assess specific spinal segment
48
Motor unit
LMN and all the fibers it innervates
49
y-motor neuron
LMN innervating mm spindles to regulate sensitivity for sensing mm contractions during voluntary movement
keeps it tight so mm spindles are sensitive to stretch
50
Corticospinal tract divisions
90%=decussating fibers (lateral CST) cross midline in medulla
10%=uncrossed (Medial CST)
51
Spinal interneurons
located in gray matter
can be glutamatergic (excitatory) or GABA/Glycinergic (inhibitory)
usually stay in segment, axons don't travel
52
What are LMN alpha neurons?
LMN ARE alpha motor neurons
innervate skeletal mm
organized nuclei in anterior horn of SC
release ACh
53
Stretch reflex (Circuit, stimulus, response)
Circuit= 2 neurons
Stim= stretch
Result= contraction
Function=maintain upright posture in load conditions
Extra: negative feedback (respons eliminates stim); single segment; strongest in antigravity mm (extensors) and weakly extend to synergist mm
54
Reciprocal Inhibition (circuit, stimulus, response)
```
Circuit= disynaptic, 3 neurons
Stim= stretch
Response= relaxation in antagonist mm
```
Extra: reciprocal to stretch reflex
55
Withdrawal reflex (circuit, stimulus, response)
```
Circuit= 4 neurons, interneurons
Stim= pain in periphery
Response= pull limb away from stim
```
Extra: extent of involvement is proportionate to intensity of stimulus; extends to multiple SC levels
56
Crossed extension
produces contralateral contraction of antigravity mm
inhibits contralateral flexors
maintain upright posture during contralateral flexion reaction
Paired with withdrawal reflex
57
Is homeostasis a set number or a range?
Range; to keep range brain needs a lot of info
gets info from sensory receptors which gets funneled to hypothalamus (olfactory, visual, limbic, visceral, neuromodulatory)
58
hypothalamus
anterior and ventral to thalamus
| homeostasis and complex behaviors (reproduction, circadian rhythms)
59
Efferents from HT
neuroendocrine system (pituitary) and autonomic nervous system
60
What is the hypothalamus made of?
collection of 11 principal nuclei and each nuclei receives different information and directs responses
61
Posterior pituitary
Extension of brain
| direct release of neuropeptides into blood
62
Anterior pituitary
part of endocrine system
| influenced by hypothalamus to release hormones into blood
63
What are the three branches of the autonomic nervous system?
sympathetic
parasympathetic
enteric
64
Sympathetic nervous system
Fight or flight
moment-to-moment blood supply, body temp, viscera regulation, metabolism
12 thoracic segments and upper 2 lumbar segments
65
Parasympathetic nervous system
rest and digest
energy conservation, lower heart activity, digestion, increase secretion
gray matter of brainstem (CN II, VII, IX, X) and middle 3 segments of sacral cord
66
Adrenergic portions of ANS
Sympathetic nervous system: 2" order neurons release adrenaline onto target organs
67
Cholinergic portions of ANS
Sympathetic nervous system: 1" neuron releases ACh on 2' neurons
Parasympathetic nervous system: 1" neuron releases ACh on 2"; 2" release ACh on target organs
68
Target organs of the sympathetic nervous system
```
Adrenal gland
pupil/eyelid
secretory glands
bronchial mm
heart and blood vessels
smooth mm
sweat glands
```
69
Target organs of the parasympathetic nervous system
```
From brainstem:
pupil
lacrimal glands
salivary glands
heart
respiratory structures
GI
From SC:
bladder
bowel
sex organs
```
70
visceral afferent pathways
median forebrain bundle
| projections from nucleus of solitary tract
71
Enteric nervous system
```
automatic and self-regulating
influenced by CNS
located along walls of gut
3 neuron structure: sensory->interneuron->motor
use neuromodulatory neurotransmitters
```
72
Neuroendocrine system
hormones
| chemical messenger secreted into blood
73
What do neuroendocrine hormones do?
long term ongoing functions of the body
growth, development, metabolism
regulation of internal env
at cell level: influence rate of enzymatic reactions, active transport of molecules across membranes, gene expression, and protein synthesis
74
Anterior pituitary hormone release process
hormones synthesized in anterior pituitary influenced by trophic factors produced in HT
trophic factor is released into hyopthalamic-hypopseal tract
75
Posterior pituitary hormone release process
hormones synthesized by neurons in hypothalamus and released directly into blood from post pit
regulate water balance, labor/delivery, lactation, sexual arousal
76
Bladder function
sensory input from s2-s4 spinothalamic and DCML pathways
motor control: cortical/subcortical perception (direct to urinate or hold)
somatic s2-s4 (urethral sphincter, pelvic floor)
Parasymp NS S2-s4 (bladder contraction and urethral relaxation)
SNS: t11-L1 (bladder relaxation and urethral contraction)
77
Bowel function
sensory input s2-s4 spinothalamic and DCML pathways
motor control:
cortical perception
somatic s2-s4 (pelvic floor and external anal sphincter)
Parasym NS s2-s4 (internal anal sphincter, colon, rectum)
CN X (gut distal to splenic fixture)
78
Sexual function
sensory input: primary sensation modalities, cognitive/affective influences, s2-s4 spinothalamic/DCML
Motor output
cortical/subcortical
somatic s2-s4 (ejaculation)
Parasymp s2-s4 (lubrication and erection)
SNS T11-L1 (vaginal wall, erectile/anti-erectile, ejaculation)
79
Spinal shock
temporary loss of motor and sensation reflexes below level of injury
acute phase
flaccid paralysis, arreflexia, loss of bladder function
80
How do you know when spinal shock is over?
when reflexes at lowest SC level start to come back
81
What is the presentation of a spinal cord injury?
| think UMN and LMN pathologies
At the level of damage we would see LMN pathologies but traveling downward would see UMN pathologies
82
Acute tx of SCI
CT/x-ray to assess
immobilization
steroid meds to decrease swelling and block formation of free radicals
modest systemic hypothermia
83
What are the 4 key principles of SC repair?
1. protecting surviving nn cells from more damage
2. replace damaged nn cells
3. sitmulate regrowth of axons and target connections
4. retraining neural circuits to restore body functions
84
What are therapy goals for SCI in acute care?
```
ROM
OOB
Positioning
Education
Respiration
Skin
```
85
What are therapy goals for SCI during inpatient rehab?
```
ROM
OOB
Positioning
Education
Respiration
Skin
Mobility
ADL
strength
home modifications
family and patient education
wheelchair
bracing
```
86
Cauda equina syndrome
injury to lumbosacral nn roots
arreflexic bowel and or bladder
variable mm involvement in LE but LMN paralysis/arreflexia and variable sensation loss in LE
87
Dorsal root lesion
complete sensory loss in corresponding dermatome
88
Ventral root lesion
LMN paralysis
89
Segmental lesion
LMN paralysis and complete sensory loss
90
Vertical tract lesion
LMN paralysis at lesion level
complete sensory loss in corresponding dermatome
UMN paresis of ipsilateral MM below lesion
contralateral loss of pain/temperature sensation 1-2 levels below lesion
ipsilateral loss of discriminative touch and proprioception at and below lesion
91
Syringomyelia
dilated, glial-lined cavity in SC=central cord syndromes
92
central cord syndrome
cervical cord is the most common site
loss of pain/temperature related to crossing fibers
weak in arm mm with atrophy and hyporeflexia
may occur as a late sequelea to trauma
93
Anterior cord syndrome
```
hyperflexion
ex// MS, "SC stroke"
loss of pain and temperature sensation
UMN paralysis below lesion
LMN paralysis at involved levels
```
94
Posterior cord syndrome
trauma, tumor, MS, "SC stroke"
loss of conscious proprioception and discriminative touch
rare
95
Conus medullaris syndrome
sacral cord injury
arreflexia in bladder and bowel
LE motor varies-reflects LMN below and at lesion
LE sensory loss
96
If there is a lesion at or above C4 what would you need to breathe?
artificial support
97
If there is a lesion at or above T6 what would you need to breathe?
fine breathing in normal conditions but may need assistance
98
If there is a lesion at or above T12 would breathing be affected?
no
99
At what level do complete lesions result in ANS dysfunction and what does it cause?
T5/6
autonomic dysreflexia
poor thermoregulation
postural low BP
100
Is there any part of the brain outside of the skull?
Yes, the eyes
101
Anterior chamber of the eye
filled with aqueous humor (secreted by ciliary body) that is produced and drained at the same rate
102
What happens if too much aqueous humor is produced and not drained quickly enough?
Can increase intraocular pressure and lead to glaucoma
103
Poterior chamber of the eye
filled with vitreous humor
fills space behind lens
maintains shape
suspended with collagenous fibers
104
Do you produce more vitreous humor?
No, amount born with is the amount you have forever
105
Lens movements
can be flattened by ciliary mm relaxation- for seeing distance
when ciliary mm contracts the ciliary fibers relax and the lens rounds- good for close vision
106
Iris
dilates in low light (sympathetic)
| constricts in bright light (parasympathetic)
107
Focus/teaming
convergence=eyes point to target
accomodation= lens change
constriction= pupil sharpens focus
108
Cataracts
affect lens
protein build-up causes clouding
tx= surgery, anti-glare eyewear, env adjustments
109
Central vision
```
cones (color)
high acuity
low convergence
needs light
"what" pathway
```
110
peripheral vision
```
rods
lower acuity
more convergence
dim light
"where" pathway
```
111
Where does visual information processing begin?
The retina
112
Macular degeneration dry type
```
90%
no new vessels
loss of pigment epithelium
atrophy of retina
gradual loss
```
113
Macular degeneration wet type
growth factor stim
neovascularization
leaks and bleeds
sudden onset
114
Macular degeneration tx
dietary supplements
low vision approaches
implement mini telescopes
anti-VEGF meds for wet type
115
Lateral geniculate nucleus
layered by eye and pathway type
magnocellular LGN= dorsal stream
parvocellular LGN= ventral stream
116
Visual perception
transforms light patterns on retina into interpretation of 3D whole
initial grouping into figure and ground
attentive processing: comparing features to stored data base and arriving at conclusions
117
Binding
deciding what goes with what
| preattentive processing: parallel encoding of elemental properties
118
Optokinetic reflex
when stimulus moves, eyes automatically track it
| need cerebellar functioning
119
Saccades
brief movements to bring target image onto fovea
120
vestibulocular reflex
focus on stimulus when head moves
| need cerebellar functioning
121
smooth pursuit
steady movement used to track moving visual target on the fovea
122
what does the vestibular system do?
monitor head position in space
in ear
provides reference for somatosensory and visual system
influence balance, posture, eye position, movement, alertness
123
How does the vestibular division monitor head position?
activation of haircells (stereocillia) that project into endolymph layer
motion of head moves endolymph which opens iion channels and allow K+ to enter which depolarizes hair cells
124
Where are haircells located?
semicircular canals (ampullary cupula at base) and otolithic system
125
Otolithic system
utricle (horizontal acceleration) and saccule (vertical acceleration)
126
Structure of vestibular system
bone->perilymph (similar to CSF)->membranous labyrinth->endolymph (High K+)
127
Name the separate vestibular nuclei and the directions of their projections
Superior (rostral)
Lateral (cerebellum and SC as vestibulospinal tract)
Medial (cerebellum and SC as vestibulospinal tract)
Spinal (cerebellum and SC as vestibulospinal tract)
128
Tip Link
stereocilia connected through tip links
| when larger stereocilia moves, the tip link opens and allows depolarizing
129
Which structure does rotational acceleration?
Semicircular canals
130
Which structure does linear acceleration and static head position/gravity?
Otolithic system
131
What does the anterior canal detect?
forward and lateral movememt
132
What does the horizontal canal detect?
circular motion
133
What does the posterior canal detect?
Backward and lateral movement
134
Superior vestibular nucleus
to thalamus then to cortex for conscious perception
to reticular formation for alertness/autonomic function
to CN nuclei (III, IV, VI) for vestibuloocular reflex
135
Vestibuloocular reflex
eye movement equal and opposite to head movement
136
Medial vestibulospinal tract
descends to LMN that innervates neck flexors and extensors
bilateral; stabalize head in space
vestibulocervical reflex
137
Vestibulocervical reflex
keeps head vertical with respect to gravity
138
Lateral vestibulospinal tract
descends, ipsilateral
synapses to LMN in cervical and lumbar SC and extensor mm
stabilizes center of gravity
139
Vestibulospinal reflexes
maintain upright posture
140
ankle strategy
going on tip of toes or heels to keep from stepping forward
141
Vestibular disorder symptoms
vertigo, dizziness, nystagmus, unsteadiness
142
Treatment of vestibular disorders
address cause
compensate with other senses
habituation
143
Peripheral vestibular disorders
damage to vestibular organs and nn
| sudden onset vertigo, nausea, worsened with head movement, evoked nystagmus, may involve cochlear nn
144
Examples of peripheral vestibular disorders
neuritis, labyrinthitis, Menier's disease, benign paroxysmal positional vertigo
145
Central vestibular disorders
damage to vestibular nuclei, cerebellum, midbrain, cortex
affect integration and processing
slower onset, may have vertigo/dizziness, not position affected, maybe nystagmus
146
Examples of central vestibular disorders
```
MS
Stroke
Tumor
Cerebellar degeneration
lower Blood sugar
ischemia
```
