Sensory Physiology (Topic 9) Flashcards
1
Q
What are the two parts of a sensory pathway? (2)
A
- sensory receptor
- afferent neural pathway
2
Q
What does a sensory recpetor do? (2)
A
receive stimuli for external or internal environment
3
Q
What does the afferent neural pathway do? (2)
A
conducts information from the receptor to the CNS
4
Q
What is sensory information? (2)
A
any stimuli detected by the body, regardless of awareness
5
Q
What is sensation? (2)
A
sensory information that reaches consciousness
- Ex: temperature
6
Q
What is perception? (2)
A
the awareness of a sensation or understanding of its meaning
- Can be affected by experience/emotions
7
Q
What do sensory receptors generate? (3)
A
graded potentials (called receptor potentials) in response to a stimulus.
8
Q
What are the 5 types of sensory receptors and the type of stimulus they respond to? (3)
A
- Mechanoreceptors: physical change
- Thermoreceptors: heat
- Photoreceptors: light
- Chemoreceptors: chemical
- Nociceptors: pain
9
Q
What is a stimulus? (3)
A
energy or chemical that activates receptor
10
Q
What is sensory transduction? (3)
A
transformation of environmental stimuli into electrical (neural response)
11
Q
What are receptor cells missing? What do they still have? (4)
A
- missing voltage-gated sodium and potassium channels
- but has voltage-gated calcium channels
12
Q
What kind of potential do receptor cells have? (4)
A
graded potentials only
(b/c no V-G Na+ and K+ channels)
13
Q
What happens if positive ions flow into the cell? (4)
A
depolarization of the membrane
14
Q
What does calcium do? (4)
A
stimulate SNARE proteins
15
Q
Go over slide 4
A
mechanisms yay
16
Q
Is touch one cell or two? (4)
A
one
17
Q
Is taste one cell or two? (4)
A
two
18
Q
Go over slide 5
A
so tired lol
19
Q
How is the amount of neurotransmitter released affected by the strength of the stimulus? (5)
A
more is released with a greater stimulus
20
Q
What is a sensory unit? (6)
A
single afferent neuron with its receptive terminals
21
Q
What is the receptive field? (6)
A
area or volume monitored by a sensory unit
- Small field = high resolution
22
Q
What is modality? (6)
A
stimulus type
- ex: taste
23
Q
What is a sub modality? (6)
A
a subcategory of a type of stimulus
ex: salty, sweet, bitter, sour, umami
24
Q
T/F Most receptors are specialized for a modality or sub modality? (6)
A
true
25
T/F Very strong stimuli may produce response on any receptor? Give an Example (6)
True
- getting hit in the head too hard and seeing flashes of lights (photoreceptors are responding instead cause it was so strong)
26
Do pain receptors detect modalities? If so how, if not what do they detect? (6)
Pain receptors don't detect a single modality, they detect a strength of stimulus that might cause harm to the body
27
How do we distinguish a strong stimulus from a weak one? (7)
By stimulus intensity (stronger graded potential, causes for more action potentials)
28
What is recruitment? (7)
Stronger stimuli usually affect a larger area stimulating more receptors.
29
What are labeled lines? (8)
signals travel along distinct pathways from receptor to CNS
30
How do we determine the location of a stimulus? (8)
Through labeled lines`
31
How do we determine the location of a stimulus? (8)
Through labeled lines`
32
What is acuity? (8)
precision with which we distinguish multiple stimuli
33
What does acuity depend on? (8)
- the size of the receptive field
- amount of convergence (more convergence/less acuity)
34
Why are your lips more sensitive than your back? (8)
- a single neuron covers a smaller area (small receptive field/higher acuity)
- a single neuron covers a larger area (large receptive field/lower acuity)
35
Go over slide 9
mhm
36
What is the purpose of lateral inhibition? (10)
it is to increase acuity when you have overlapping receptive fields
37
What do neighbor receptors do to each other? (10)
inhibit each other
38
What does improving localization do to acuity? (10)
increases acuity
39
What do descending pathways do? (11)
inhibit sensory pathways
39
What do descending pathways do? (11)
inhibit sensory pathways
40
What are descending pathways composed of? (11)
interneurons
41
Where are descending pathways located? (11)
central nervous system
42
Examples of descending pathways (11)
pain pathways (Input is always inhibited to some degree)
43
Compare and contrast descending and efferent pathways (11)
Compare:
- both start at the CNS (brain) and travel away from it
Contrast:
- Descending never leaves the CNS to go to the PNS
- descending inhibits responses
- Efferent Moves from the CNS to the PNS
- Efferent targets an effector to make a response
44
T/F the sensory areas of the cortex have specific ascending pathways (12)
true
45
Ascending pathways of the cortex move where? (12)
- Pass to brainstem & thalamus
- Then to specific areas of cerebral cortex.
46
olfactory pathways bypass _____ and go directly to ____ _____ & _____ _____ (12)
- thalamus
- olfactory complex & limbic system
47
What does the Somatosensory cortex have? (12)
Information from somatic receptors – skin, skeletal muscle, tendons & joints
48
Where do most cortex pathways cross to? (12)
the opposite side of the brain
49
What are association areas? (12)
- Site of complex integration
- arousal, attention, memory, language
Ex. Visual/Somatosensory
50
What are general senses? (13)
- Touch and pressure
- Sense of posture and movement
- Temperature
- Pain
51
What are somatic sensations? (13)
from the skin, muscles, bones, tendons and joints
52
What are visceral sensations? (13)
from the organs. Usually have few receptors
53
What are special senses? (13)
- sight
- smell
- hearing
- balance
- taste
54
What type of receptors are touch and pressure receptors? (14)
mechanoreceptors
ex: hair bending, pressure, vibrations, touch
55
Characteristics of touch and pressure receptors (14)
- Neuron ending are linked to a capsule containing collagen fibers (highly specialized)
- Receptor fields vary:
Small: provide precise information
Large: may be whole finger or large part of palm. Signal info about skin stretch or joint movement
56
What type of receptors are posture and movement receptors? (15)
- Muscle spindle stretch receptors
- Mechanoreceptors in joints, tendons, ligament, skin
57
What plays a role in balance? (15)
vision and vestibular (balance) receptors
58
What is kinesthesia? (15)
sense of movement of a joint
59
What is proprioception? (15)
sense of posture
60
Characteristics of temperature receptors (16)
- Small neurons with little of no myelination
- Free nerve endings
- Sensors are ion channels in the axon terminals
- Transient Receptor Potential (TRP) proteins
- Various TRPs that open at a range of temperatures.
61
What are pain receptors stimulated by? (17)
Free axon-terminal unmyelinated nociceptors stimulated by extreme deformation, temperature or chemicals associated with cell damage
62
What are pain receptors stimulated by? (17)
Free axon-terminal unmyelinated nociceptors stimulated by extreme deformation, temperature or chemicals associated with cell damage
63
How do opiates inhibit pain receptors? (17)
- inhibits neurotransmitter release
- antagonist to the pathway
- causes hyperpolarization
64
What does endogenous vs exogenous mean? (17)
- made by the body
- taken into the body
65
How do opiates work? (17)
works by mimicking our naturally occurring neurotransmitters.
66
What is referred pain? (18)
- Brain does not distinguish stimuli coming from visceral and somatic branches of the same spinal nerve.
- Feel pain from an internal organ as another area of the surface of the body.
-( ex: pain in left arm during a heart attack)
67
What is the anterolateral pathway? (19)
- synapse occurs in the spinal chord
- pain, temperature
68
What is the dorsal column pathway? (19)
- synapse occurs in the brainstem
- touch, pressure, position, movement
69
Characteristics of the somatosensory pathway (19)
- Stimuli arrive to the cerebral cortex through at least 2 neurons
- One synapse occurs in the thalamus
70
Compare and contrast anterolateral and dorsal column pathway (19)
Similarities:
- both pathways for general senses that end in the somatosensory cortex
- 3 cells involved (neuron)
- 2 synapses (interneurons)
- Both start on the right side and end on the left side of the brain.
- both second synapse in the thalamus
- cross to other side of body after the first synapse
- both sensory pathways (afferent)
Differences:
- first synapse in different locations (ant.= in spinal cord/ dorsal.= in brainstem)
- ant.= pain and temp
- dorsal= touch, pressure, movement
71
What modalities are processed in the somatosensory cortex? (20)
72
Why does more of the somatosensory cortex focus on lips than your elbow? (20)
- higher acuity
- more labeled lines
- more important to know what's going to your mouth than elbow
73
What are the two components of the eyes? (21)
- an optical component
- a neural component
74
What does the optical component of the eye do? (21)
Focuses the visual image onto
the receptor cells
75
What does the neural component of the eye do? (21)
Transforms visual image into a
patter of graded and action
potentials
76
What type of energy is light? (21)
electromagnetic
77
What defines color and what is it? (21)
wavelength: the distance from peak to peak
78
What are the only wavelengths we can detect? (21)
Visible light (a range of the spectrum)
79
What is the anatomy of the eye? (22)
three-layered fluid-filled ball
- sclera
- cornea
- choroid
- iris
- ciliary muscle and zonular fibers
- retina
- fluids
80
What is the sclera? (22)
tough & white (opaque) provides structure & points for
muscle attachment
81
What is the cornea? (22)
clear; lets the light enter
82
What is the choroid? (22)
Dark, pigmented at the
back of the eye
* Absorbs “extra” light
83
What is the iris? (22)
- Gives eye color
* Muscles of iris determine
size of pupil
84
What do the Ciliary muscle & Zonular fibers do? (22)
Work to together to alter shape of the lens
85
What is the retina made of? (22)
Neurons & photoreceptors
86
where is aqueous humor found? (23)
between iris and cornea
87
where is vitreous humor found? (23)
jelly-like substance between lens & retina
88
What are features of the retina? (23)
– Macula lutea -> area
free of blood vessels
– Fovea centralis -> pit
within the macula; high
density of cones for
visual acuity
– Optic disc -> neurons
exit the eye as the optic
nerve; no receptors in
this area
89
What is refraction? (24)
When a light wave crosses
from air to a denser
medium (like your cornea
and lens), the wave bends.
90
Where do light waves converge? (24)
on the retina
91
Why is an image formed upside down and what does the brain do to correct it? (24)
Because of refraction, the image is formed upside down on the retina. The brain restores perception
to proper orientation.
92
Objects in the center of the field of view are focused on what? (24)
fovea centralis
93
Why is the shape of the lens changed? (25)
so that focus is on the retina
94
in focus vs out of focus (muscles and lens) (25)
in focus (far):
- relaxed muscles, tension on fibers, flattened lens, light rays are nearly parallel
in focus (near):
contracted muscles, slackened fibers, rounded lens, near object with accommodation
out of focus:
- relaxed muscles, light rays from near object diverge
95
What is presbyopia? (26)
lens loses elasticity
96
What is a cataract? (26)
changes in lens color/opacity
97
What is glaucoma? (26)
retinal cells are damaged due to increased
pressure
98
What is myopia? (26)
Nearsighted = distant objects hard to see
99
What is hyperopia? (26)
Farsighted = close objects hard to see
100
What vision defects are common in older adults and those with health risks? (26)
- presbyopia
- cataracts
- glaucoma
101
What vision defects are common in people of all ages and are due to eye shape? (26)
- myopia
- hyperopia
- astigmatism
102
What are rods? (26)
photoreceptors that are extremely sensitive and work in low light
103
What are cones? (26)
photoreceptors responsible for color and only work in bright light
104
What does pigment epithelium and choroid do? (26)
absorbs the light that has passed the receptors
105
Why is it important that the light in the back of your light gets absorbed? (26)
receptors would be constantly triggered and we wouldn't be able to see
106
Where are receptors located in the eye? (26)
back of the retina
107
What do pigments do? (27)
absorb light
108
What do photoreceptors contain? (27)
photopigments that absorb light
109
What photopigments are in rods? (27)
rhodopsin
110
What photopigments are in cones? (27)
3 unique photopigments
111
What are photopigments composed of? (27)
membrane-bound proteins (opsin)
112
What does opsin surround? (27)
a light-sensitive molecule called retinal
113
Why is opsin more sensitive to a different portion of the spectrum? (27)
each opsin binds to retinal in a different way
114
What is phototransduction? (28)
taking a light stimulus into an electrical signal
115
What happens when you step from bright sunlight to a darkened room? Why?
116
At rest (no light) what is the potential of the cell? (28)
depolarized (-35mV)
117
In response to light, what is the potential of the cell? (28)
hyperpolarized (-70mV)
118
Wat does guanylyl cyclase do? (28)
Takes GTP and turns it into cyclic GMP
119
Why are photoreceptor cells generally depolarized? (28)
cGMP activates cation channels that bring in positive ions, making membrane potential more positive
120
What does cGMP phosphodiesterase do? (28)
converts cGMP to GMP
121
How does light hyperpolarize the cell? (28)
- light strikes retinal
- opsin changes and activates transducin
- cGMP-phosphodiesterase activates and changes cGMP to GMP
- cation channels close due to lack of cGMP
- cell potential hyperpolarizes (-70mV)
122
T/F when struck by light, a photoreceptor hyperpolarizes (28)
True
123
What kind of potential do photoreceptors and bipolar cells have? (29)
- only graded potentials b/c they do not have voltage-gated channels
124
What cells are the first in the neural pathway with action potentials? (29)
ganglion cells
125
What forms the optic nerve? (31)
the axons of ganglion
126
What gives us binocular vision? (31)
2 optic nerves meet at the optic chiasm where some fibers cross
127
What’s the advantage of binocular vision? (31)
depth perception
128
What is sound? (32)
Energy transferred through a medium (gas, liquid, or solid) causes the molecules to vibrate
129
Does sound occur in a vacuum? (32)
no, there are no particles to vibrate
130
What is the zone of compression? (32)
where molecules are more dense
131
What is the zone of rarefaction? (32)
where molecules are less dense
132
What does amplitude affect? (32)
loudness
133
What would make the sound of a tuning fork louder? (32)
the bigger the difference between the zone of compression and rarefaction, the tall your wave (higher the amplitude)
- (Difference in pressures between zones of compression and rarefaction)!!!
134
What is sound measured in? (33)
decibels (dB)
- a logarithmic scale
135
What determines pitch? (34)
the waves frequency
- (higher frequency = higher pitch)
136
What is frequency measured in? (34)
hertz (Hz; cycles/second)
137
What is the range of human hearing? (34)
20-20,000 Hz
138
What are the steps of sound transmission? (35)
1- entrance of sounds wave into external auditory canal
2- transmission from tympanic membrane through the middle ear to the cochlea (inner ear)
3- membrane of oval window moves
4- movement of basilar membrane
139
What transfers the vibrations to the oval window, the membrane-covered opening of the scala vestibuli? (36)
three bones
140
What is the cochlea? (37)
spiral-shaped, fluid-filled space in temporal bone
141
What is the cochlear duct? (37)
membranous tube filled w/ endolymph
142
On either side of the duct, compartments are filled with ___ (37)
perilymph
143
What causes the basilar membrane to vibrate? (37)
pressure differences
144
What are the organs of corti? (40)
- sit on the basilar membrane
- contain hair cells (mechanoreceptors)
- embedded in the endolymph
145
What is the cranial nerve made of? (40)
Axons of afferent neurons join to form a branch
146
How are sounds of different pitches distinguished? (41)
waves with different frequencies stimulate the basilar membrane at different places; activating different hair cells (diff. hair cells= diff. labeled lines = diff. places in cortex)
147
How are sounds of different loudness distinguished? (41)
stereocilia bend more
- if bent more -> more potassium goes in -> more graded depolarization -> more NT released -> more graded in afferent neuron -> more action potentials
(higher amplitude = more action potentials)
148
What are the ear hair cells called? (41)
stereocilia
149
What happens when stereocilia bend? (41)
potassium channels open and flow IN to the cell
150
What is the vestibular apparatus? (42)
Connected series of endolymph-filled membranous tubes
151
What are the components of the vestibular system? (42)
- 3 semicircular canals
- Utricle
- Saccule
152
What are the receptors of the vestibular system? (42)
hair cells
153
What detects rotation of the head along three axes? (43)
three semicircular canals
154
What are the receptors of the semicircular canals? (43)
- Receptor cells have stereocilia encapsulated in the cupula
- cupula bends -> bends the stereocilia
(fluid pressure causes bending of the hair)
155
What provides information about linear acceleration
(up & down; back & forth)? (45)
utricle and saccule
156
What are hair cells covered in? (45)
gelatinous material embedded with calcium carbonate crystals
157
What does the utricle respond to? (45)
Hair cell stand upright
- Respond to bending (tipping your head) or horizontal accelerations
158
What does the saccule respond to? (45)
Hair cells stand at right angles
- Respond to moving from lying to standing and vertical accelerations
159
Where are taste buds found? (46)
the walls of the lingual papillae
160
What are the basic types of taste receptors? (46)
sweet, salty, bitter, sour, umami
161
Where do olfactory receptor neurons lie? (47)
lie in the olfactory epithelium, in the upper part of the nasal cavity
162
Where must odorants pass in order to be detected? (47)
must pass through the air and dissolve into the mucus layer to be detected.
163
What do olfactory receptors have? (48)
one enlarged dendrite with nonmotile cilia.
164
What do the cilia of olfactory receptors contain? (48)
The cilia contain the receptor proteins that provide the binding sites for odor molecules.
165
How many types of odorant receptors does each cell have? (48)
only one
166
How many types of odorant receptors do humans have? (48)
about 400
167
What forms the olfactory nerve? (48)
The axons of the neurons form the olfactory nerve (cranial nerve)
