Sensory Physiology Flashcards
1
Q
afferent division
A
All input, going in
2
Q
afferent divides into
A
- somatic sensory
- visceral sensory
- special sensory
3
Q
Somatic sensory
A
general senses:
- touch, pressure, temperature
- external environment
4
Q
visceral sensory
A
[glucose], osmolarity, O2, blood pressure
- internal environment
5
Q
special sensory
A
- taste, smell, vision, hearing, equilibrium
- external environment (special)
- –> limited to cranial nerves
6
Q
sensory receptors function
A
convert chemical/physical stimulus into nerve signal
7
Q
sensation
A
awareness of stimulus signal must reach CNS –> cerebral cortex
8
Q
sensory receptors
A
- specialized dendritic endings that detect stimulus on neuron
OR - receptor cell that talks to neuron
9
Q
sense organ
A
neurons and other tissue that enhance sensory response
ex: eye, ear
10
Q
thermoreceptors
A
temperature = warm or cold
11
Q
photoreceptors
A
photons of light
- detect light
- produce graded potentials
12
Q
nociceptors
A
pain (specialized chemoreceptors)
13
Q
chemoreceptors
A
chemicals = NTs, sugars, ions, amino acids. etc.
14
Q
mechanorecptors
A
physical deformation (stretch, pressure, touch)
15
Q
proprioceptors
A
body position and movement (muscles, tendons, joints)
- specialized mechanoreceptors
16
Q
receptor potential
A
stimulus opens ion channels on sensory neuron or sensory cell, which produces a graded potential
- analogous to local potentials
- same characteristics
- most EPSPs
- increase magnitude of stimulus = increase frequency of APs
17
Q
sensory coding
A
- intensity
- location
- duration
- type (modality)
18
Q
receptive field
A
area that leads to activation of a particular neuron
19
Q
stimulus intensity
A
determined by action potential frequency
stronger stimuli can also affect a larger area, which recruits additional afferent neurons –> send more signals
- increase summation of receptor potentials
- stronger stimulus = more ion channels
- open in neuron = more APs
20
Q
Weber-Fechner Principle
A
the greater the background stimulus, the greater an additional change must be for it to be detected
- ex: holding 30g weight can barely detect 1g change
- holding 300g weight can barely detect 10g change
- holding 30g weight would notice 10g change
21
Q
stimulus location
A
- precision with which we can locate a stimulus is determined by size and overlap of the receptive fields of afferent neurons
- smaller receptive field = more precise indication of location
- receptor density is greatest at center of the receptive field
- visceral organs have large receptive fields = hard to pinpoint stimulus
22
Q
one large receptive field
A
stimulus anywhere in receptive field activates same neuron
- back = about 7 cm –> cannot sense 2 touches <7 cm apart
23
Q
three small receptive fields
A
finger = about 1 mm –> can sense 2 touches > 1 mm apart
24
Q
high frequency of APs mean two things
A
- moderate stimulus at A
OR - strong stimulus at B
25
lateral inhibition
enhances the contrast between the center and periphery of a stimulated region to pinpoint location
26
what is the most important mechanism for to pinpoint a location?
lateral inhibition
27
inhibitory
decreases the number of APs from surrounding neurons
28
afferent neurons
- recruit inhibitory interneurons to decrease stimulus in adjacent neurons
- greatest inhibition will come from most stimulated neuron
29
examples of lateral inhibition
- pressing tip of pencil against finger
- hair movement
- retinal processing to increase visual acuity
- temp and pain pathways have poor lateral inhibition (difficult to pinpoint)
30
sensory adaptation
- despite continued stimulus, AP frequency decrease over time
- become less aware of stimulus
31
phasic
rapid adaptation
32
phasic example
smell, hair movement (clothes on skin, hot bath)
33
tonic
slow adaptation
34
tonic example
proprioceptors, pain
| - must be aware of body position at all times
35
stimulus type
different receptors have different designs, which make them preferentially sensitive to one stimulus modality
36
labeled line code
action potentials from each receptor then travel along unique pathways to a specific region of the CNS associated with that modality
ex: will "see" light if pressure on eyeball
37
sensory pathway
spinal cord --> thalamus --> cerebral cortex
38
decussate
cross L/R
39
auditory cortex
temporal lobe
40
somatosensory cortex
general senses to parietal lobe
41
taste cortex
parietal lobe
42
visual cortex
occipital lobe
43
olfactory cortex
info does NOT go thru thalamus first
| - temporal lobe
44
sensory interpretation
association areas of the cortex integrate and process sensory input into perception
45
factors that affect perception
1. receptor adaptation
2. emotions, personality, experience
3. filtering by the thalamus
4. damaged pathways (ex: phantom limb), drugs
5. remember weber-fechner principle
46
taste
- gustation
| - chemoreceptors
47
where are taste buds found?
lingual papillae
48
how many taste buds in the mouth and throat
3,000-10,000
49
vallate papillae
about 250 taste buds each
50
fungiform papillae
about 3-5 taste buds each
51
filiform papillae
- sense texture
| - mechanoreceptor
52
primary taste senstations
- sweet
- sour
- salty
- bitter
- umami
53
sweet
sugars
54
sour
acids
55
salty
Na+/K+
56
bitter
alkaloids
57
umami
amino acids
58
physiology of taste
1. dissolved food molecule
2. chemoreceptor activated on taste cell
3. NT released onto sensory neuron
4. CNs VII, IX, X take info thru thalamus to gustatory cortex (parietal lobe)
- rapid adaptation
59
basal cell
stem cells replace taste cells every 7-10 days
60
perception of taste influenced by:
- differential activation of 5 receptor types
- smell (80%)
- sight
- texture
- temperature
- other substances in foods (ex: that stimulate pain)
- -> ex: spices, peppers
61
physiology of smell
1. odorant molecule dissolved in mucus of olfactory epithelium
2. odorant receptor on olfactory cell (neuron) activated (1 of 1000 types)
3. labeled line thru olfactory bulb
- rapid adaptation (phasic receptors)
62
perception of smell influenced by:
- attentiveness
- hunger
- gender
- age
- experience
63
cochlea
hearing
64
vestibular branch
equilibrium
65
sound waves
audible vibration of molecules
66
frequency
pitch
- cycles of movement per second
- determined by region of basilar membrane displaced = pitch
67
amplitude
loudness
| - magnitude of movement of basilar membrane = increased number of APs
68
physiology of hearing
1. tympanic membrane deflects, "vibrates"
2. middle ear bones move
3. membrane in oval window moves
4. basilar membrane moves by sound vibrations
5. tectorial membrane doesn't move --> hair cells pushed against tectorial membrane
6. sterocilia bend against tectorial membrane tip links pull ion channels open (K+)
7. K+ flows in to depolarize cell
8. Voltage gated Ca+2 channels open
9. NT released onto CN VIII (cochlear nerve)
69
three fluid-filled chambers in the ear
- scala vestibuli
- cochlear duct
- scala tympani
70
what contains endolymph?
cochlear duct
71
what contains perilymph
- scala vestibuli
| - scala tympani
72
perilymph
similar to CSF
73
endolymph
- high in K+
- low in Na+
- K+ higher than CSF of hair cells
- -> only place in the body this occurs
74
tectorial membrane
stationary
75
hair cells
- mechanoreceptors
- easily damaged by intensity noises (concerts, jet engine, construction equipment)
- can also be damaged by chronic exposure to low intensity
76
primary auditory cortex
temporal lobe
77
inferior collculus
midbrain (reflexive movements of head)
78
how many tastes can a human distinguish?
about 10,000
79
how many sounds can a human distinguish?
about 400,000
80
how many tastes can a human distinguish?
perceive hundreds
81
static equilibrium
perception of orientation of head when stationary
82
dynamic equilibrium
perception of motion/acceleration
83
types of dynamic equilibrium
- linear acceleration
| - angular acceleration
84
linear acceleration
change in velocity in straight line
85
angular acceleration
- "rotational equilibrium"
| - change of rate of rotation
86
vestibule
- utricle
| - saccule
87
utricle
horizontal plane
88
saccule
vertical plane
89
utricle and saccule
Brain interprets orientation of head by comparing input from both:
- -- static equilibrium
- -- linear acceleration
90
otoliths
ear stones
91
where are otoliths?
embedded in gelatinous fluid
| - when head position is changed, fluid bends hair cells
92
semicircular ducts
- angular acceleration (rotational equilibrium)
- detect rotation in 3 different planes
- -- "yes"
- -- "no"
- -- "lateral"
93
vestibuloobular reflex (VOR)
rotate in equal/opposite direction to "keep eye on target"
94
light
- electromagnetic radiation
- visible light (400-700nm)
- detected by photoreceptors
- -> rods and cones
95
neutral tunic contains
- retina
| - fovea centralis
96
retina
photoreceptors
97
fovea centralis
increased concentration of photoreceptors
- image focused here
- high concentration of cones
98
fibrous tunic contains
- sclera
| - cornea
99
sclera
connective tissue outer layer
100
cornea
clear anterior surface
| - bends light rays most
101
vascular tunic contains
- choroid
- iris
- ciliary muscle
102
choroid
pigmented vascular layer
103
iris
muscles control diameter of pupil
104
ciliary muscle
change shape of lens
105
rest of the eye
movement and focusing imaging
106
tunics
fluid-filled ball
107
refraction
light bends
108
lens
fine tunes
| - can change shape with ciliary muscles to focus light on retina
109
accommodation
change curvature of lens to focus on near objects
- shape of lens controlled by ciliary muscle
- -> parasympathetic control
110
distant vision
- ciliary muscle relaxed
- suspensory ligament taut
- lens thins
111
near vision
- ciliary muscle contracted
- suspensory ligament relaxed
- lens thickens
112
pupillary constriction
to help focus light rays, the iris changes the pupil size to regulate amount of light that enters the eye
- makes edges of image clearer
113
pupil dilated
sympathetic effect
114
pupil constricted
parasympathetic effect
115
myopia
nearsightedness
| - can't see objects far away clear
116
nearsightedness
eyeball too long
117
nearsightedness corrected
concave lens diverges light rays
118
hyperopia
farsightedness
| - can't see objects close up
119
farsightedness
eyeball too short
120
farsightedness corrected
convex lens converges light rays
121
optic disc
- blind spot
- no photoreceptors here
- where axons converge to become optic nerve (lots of blood flow)
122
visual filling
brain "fills in" information based on background
123
pigment epithelium
absorbs stray light
| - no reflection
124
bipolar cell
produce graded potentials
| - no action potentials
125
horizontal / amacrine cell
modify signal using lateral inhibitor to enhance contrast
126
ganglion cell
- action potentials
- axons of ganglion cells from optic nerve (CN II)
- true neurons
127
rods
- respond in dim light
- located in periphery (alert us to motion)
- high sensitivity
- low acuity
- no color vision (black and white)
128
cones
- respond in bright light
- dense around fovea
- high acuity (sharp image)
- low sensitivity
- color vision
129
outer segment of rod/cones
contains photopigments
130
inner segment of rod/cones
organelles
131
night vision
many rods converge to stimulate one ganglion cell
- large receptive field
- up to 100 rods / bipolar cells
132
spatial summation of night vision
- increase sensitivity
| - decreased resolution
133
day vision
each cone has a 'private line' to the brain
- small receptive field
- increased resolution
- decreased sensitivity
- NO summation
134
photopigments: rods
rhodopsin
135
photopigments: cones
photopsins
136
cone has 1 of 3 types of photopsin:
- S (blue) cone
- M (green) cone
- L (red) cone
137
blue light
benefiting during daylight hours
- boost attention, reaction times, and mood
- suppressed melatonin for about twice as long as green light and shifted circadian rhythms by twice as long
138
what color should the numbers be for an alarm color?
red
139
red light
has the least power to shift circadian rhythm and suppress melatonin
140
signaling in the dark process
1. cGMP is high --> cation channels open
- rod cell is depolarized
2. glutamate is released onto bipolar cell (IPSP)
3. bipolar cell hyperpolarizes
4. no excitatory neurotransmitter released onto ganglion cell
5. No action potentials to brain
141
rhodopsin
GPCR (opsin) + retinal (form of Vitamin A)
142
retinal
light sensor
143
visual signal transduction pathway
1. rhodopsin absorbs photon of light
2. Cis-retinal isomerize to trans-retinal
- - causes conformational change in opsin
3. opsin triggers reaction cascade that breaks down cGMP
144
signaling in the light process
4. cGMP levels falls --> cation channels close
- - rod cells hyperpolarizes
5. no glutamate is released onto bipolar cell
6. bipolar cell depolarizes
7. excitatory neurotransmitter released onto ganglion cell
8. action potentials to brain via CN II
145
dark adaptation
when moving from bright light to dark
- rhodopsin was bleached in light
- takes about 5 min to regenerate 50% of bleached rhodopsin
- 20-30 min for max sensitivity
146
light adaptation
- when moving from dark to bright light
- rods all become bleached because image is too bright
- poor contrast
- adaptation occurs quickly
147
lateral inhibition
- horizontal cells
| - amacrine cells
148
ON bipolar cells
- depolarize (no glutamate from rods)
| - release NT --> stimulate ganglion cell to have AP
149
OFF bipolar cells
- hyperpolarize (and glutamate)
- no NT release
- no AP ganglion cell
