Lecture 9 - Sensory Systems Flashcards
1
Q
What are the stimuli potentially available to animals and human and what type are they
A
Mechanical Chemical Photic Thermal Pain Kinestheia External stimuli
2
Q
What is receptor for chemical stimuli and what does it detect
A
Chemoreceptor
Taste, smell
3
Q
What is receptor for mechanical stimuli and what does it detect
A
Mechanoreceptors
Touch, hearing, balance and acceleration
4
Q
What is receptor for photic stimuli and what does it detect
A
Photoreceptors
Vision
5
Q
What is receptor for thermal stimuli and what does it detect
A
Thermoreceptors
Hot/cold
6
Q
What is receptor for pain stimuli and what does it detect
A
Nocireceptors Various ( chemical, mechanical etc )
7
Q
What is receptor for kinestheia stimuli and what does it detect
A
Proprioreceptors
Various ( muscle spindles etc )
8
Q
What does stimuli cause
A
Small depolarisation in receptor
9
Q
What are the types of internal stimuli
A
Mechanical - baroreceptors
Chemical - Blood O2, /CO2, glucose etc = control levels of respiration
10
Q
What are baroreceptors
A
Stretch receptors in the aoritc arch and cartoid body
11
Q
What are mechanoreceptors sensitive to
A
Diameter of arteries = informed of blood pressure
12
Q
What is magnetoreception and what animals use it and why
A
Animal like birds and fish percieve the Earth’s magnetic field
Used for navigation ( magnetoreception ) - allows them to migrate, know where abouts in world they are
13
Q
What non - human animals use mechanoreceptors and why
A
Aquatic animals such as fish and some amphibia have lateral lines ( side of fish ) to sense water movements
14
Q
What is electroreception and what animals use it and why
A
Sharks can detect fish buried in sea by detecting their electric fields - sense electricity/electrical signal - action potentials
- allows them to migrate, know where abouts in world they are
15
Q
What wavelength of light do we see
A
We see from about 400nm ( violet ) to 750nm ( red )
16
Q
What wavelength of light do animals see
A
Fish, birds and insects see UV
Snakes and beetles sensitive in infrared
17
Q
What are all these examples of
A
Sensory receptors - senses
18
Q
What is role of sensory receptors and what is the term called
A
Converting sensory stimulus to neurobiological activity
Transduction
19
Q
What is flow chart of stimulus to CNS
A
Stimulus - transduction - receptor potential - action potential - CNS
20
Q
What does a stimulus cause
A
Change in membrane permeability = receptor potential
21
Q
What is receptor potential result of
A
Change in membrane permeability
22
Q
What does receptor potential cause
A
Action potential - signal to CNS
23
Q
Where is action potential carried to
A
CNS
24
Q
What happens if threshold reached
A
Action potential ( opens Na+ channels - small depolarisation )
25
What is the same here
Receptor cell and sensory neuron
26
How many cells in each nostril that are sensitive to smelll
5 million
27
What happens to most sensory cells
Most Die eventually
28
What is receptor in smell and what is it
Olfactory receptor
| Sensory neuron - stimulated directly by odor molecule
29
What is stimuli in smell and what does it activate
Odour molecule
| Sensory neuron
30
What happens to the odour molecule
Dissolves in nasal mucus
Binds to receptors covering cilia on surface of bipolar olfactory neurons
Opens ion channels
Action potential in receptor - transmitted to brain ( cranial nerve )
31
What does cranial nerve do
Take information from nose to brain
32
What happens to olfactory receptors
Regenerate ( replaced ) by epithelial cells - turn into new sensory neurons
33
Summary of smell
Molecule to nose
Chemicals dissolve in mucus
Sensory cells = bipolar neurons - surface = cilia = increase SA. 2 processes coming out
Molecule onto protein receptor - Na channel - Na into bipolar neuron = action potential - CNS
34
What doesnt generate action potential
Specialised receptor cell
35
Which synapses generate action potential
Synapses with sensory neuron
36
What is gustatory receptor
Specialised receptor cell involving specialised cells
37
Where are our 10,000 taste buds located
On raised papillae of tongue
38
What is receptor potential
When a receptor cell produces a small depolarisation only in sensory cell
39
How many cells is taste bud made of
60 cells
40
What does a small depolarisation trigger
Action potential in sensory neuron - CNS
41
What is the base of the receptor cell
Sensory neuron
42
What do the molecules/food do
Dissolves in saliva
| Latches onto protein receptors
43
What do different regions of the tongue respond to
The four different qualities that make up all tastes
| Sensitive to different ones
44
What does an accessory structure do
Modifies stimulus before it hits receptor cell and determines what receptor cell is sensitive to
45
Examples of accessory structures
Membrane ( hearing )
| Vestibular system e.g. hair
46
What are tactile receptors/receptor cells associated with
Accessory structures
47
What does function of sensory receptors of skin depend on
Nature of accessory structure
48
What is sound
Pressure waves in air / variations in air pressure ( perceived by cells in ear)
49
Transduction of ear
Ears turn sound into neurobiological signals the brain can interpret
50
What do ears turn sound into
neurobiological signals the brain can interpret
51
What produces pure sounds
Tuning fork
52
What is hearing
Turning sound into electrical activity within ear
53
When is air moved out
High pressure
54
When is air moved in
Low pressure
55
What happens when pressure makes membrane vibrate
Air pushed in and out
56
What does different notes produce
Different notes/objects - different frequencies
57
What do pure notes combine to form
More complex sounds ( sound quality )
58
Which notes are more frequent - higher or lower
Higher
59
Which notes are less frequent - higher or lower
Lower
60
What is acuity
Tell 2 sounds apart
61
What are most sounds
Not pure notes - combination of pure notes forming more complex sounds
62
What are the 3 regions of ear
- Outer ear
- Middle ear
- Inner ear
63
What does outer ear consist of
Ear canal
64
What does middle ear consist of
Stapes
Incus
Malleus
Ear drum
65
What does inner ear consist of
Cochlea
| Semicircular canal
66
Where is pinna found
Outer ear
67
What is role of pinna
Serves to channel sound into the external auditory meatus ( tube - you stick your finger in )
Takes sound to tympanic membrane
68
What is tympanic membrane
Ear drum
69
What happens when sound impinges on tympanic membrane
Vibrates
| These vibrations are transferred by middle ear to cause movement of oval window - movement of fluid in inner ear
70
What happens to tympanic membrane in areas of high pressure
It moves in
71
What happens to tympanic membrane in areas of low pressure
It moves out
72
What happens during beginning of transduction
Turns changes in air pressure into movement of tympanic membrane
73
What do you need to convert movement of tympanic membrane into and why is this hard
Fluid movement in inner ear
| Harder than in air because fluid is resistant to movement
74
What is oval window
Junction to inner ear
75
What is middle ear filled with
Air
76
What are the 3 bones in the middle ear
- Malleus
- Incus
- Stapus
77
What do the 3 bones of middle ear do
Transfer vibration of tympanic membrane to the oval window
78
What does the Eustacean tube do
Connect the middle of ear to the Nasopharynx =equalises pressure of middle ear to atmospheric pressure
79
What is nasopharynx
Back of throat
80
What can 2 muscles do and how is this done
Freeze the bones of the middle ear = protects against loud sounds = turns off hearing.
When muscles contract = stops being transmitted - ossicles held solid - cant transfer vibrations
81
What is size of pressure changes in sound
Tiny
82
What do pressure changes in sound result in
Very small vibrations of tympanic membrane, however....
| vibrations of tympanic membrane must cause fluid movement in inner ear - requires much greater pressure change
83
What is role of middle ear
Amplify movement of tympanic ( sound ) membrane - acts as impedance matching device
Takes small vibrations of tympanic membrane and turns it into large vibrations of oval window
84
What are 2 ways to amplify movement of tympanic membrane
1. Pressure on tympanic membrane is spread over a large SA. The area of the oval window is much smaller, concentrating pressure = more effective ( bigger movements )
2. Middle ear ossicle acts as a lever system = small movements amplified
85
What happens as atmospheric pressure lowers
Tympanic membrane bows out - curves in in higher pressure
86
What does the valsalva membrane do
Equalises pressure in middle ear and atmosphere
87
What does Eustacean tube do and why
Equalises pressure
| Want pressure outside ear to be same as pressure inside ear otherwise tympanic membrane won't work properly
88
What does inner ear do
Subserves both auditory and vestibular functions
| Bony systems of tubes
89
What does inner ear consist of
Bony labyrinth filled with perilymph ( fluid ) suspended in which a membranous labyrinth containing endolymph
90
Endolymph
- Fluid
| - Lots of K+
91
What is inner ear divided into
Cochlea ( coiled )
Vestibule ( bony )
3 semi - circular canals
92
What is coiled cochlea
Snailed like structure ( hearing )
93
What is vestibule
Containing membranous saccule and utricle ( vestibular )
94
Semi circular canals
Orientated in 3 planes of space - coming of membranous sacs
95
What is ampulla
Where the semi - circular canals join onto utricle = swelling
96
How is cochela divided
Internally by membranes that run length of cochlea
97
What is cochlea divided into
- Upper chamber - Scala Vestibule
- Lower chamber - Scala tympani
- Third chamber - Scala media
98
What contains organ of corti
Scala media
99
What is scala media filled with
Endolymph
100
What is Scala Vestibule and Scala tympani filled with
Perilymph
101
Where do Scala Vestibule and Scala tympani join
Helicotrema - tip of cochlea
102
What happens when stapes is pushed in
Movement of perilymph in scala vestibule - transferred to scala tympani = causes round window to bulge out
103
What does vestibular membrane do
Seperates scala vestibule from scala media
104
What does organ of corti sit on and what does that do
Basement membrane
| Divides scala media from scala tympani
105
What is organ of corti
4 rows of hair cells ( cells with cilia on top - sensory cells) resting on basilar membrane
106
What is on top of cilia and what is it known as
Tectorial membrane
| Accessory structure
107
What is the cilia on top known as
Stereocilia
108
What are stereocilia on surface of hair cells embedded into
Gelatinous membrane - tectorial membrane = accessory structure ( on top of cilia )
109
What are the superficial stereocilia
Sensory receptors, innervated by sensory neurons
110
What does sensory neuron do
Produce action potential
111
What does sensory cell cause
Small depolarisation
112
Which part of membrane vibrates most to high frequencies and why
Basilar membrane
| Smaller and more taut near stapes
113
What kind of frequencies are produced further from stapes
Wider and looser
114
What responds to lower frequencies
Basilar membrane
115
What kind of frequencies are produced closer to stapes
Higher frequencies
116
Do points on basilar membrane vibrate at same frequencies
No - different
117
What happens to stereocilia at rest
Embedded in tectorial membrane - unbent - sensory neurons firing few actions potentials
118
What happens when basilar membrane rise/go up and why
Stereocilia bent
| Due to mass of tectorial membrane
119
Why does basilar membrane rise
Due to travelling wave initiated by a sound
120
What happens when basilar membrane falls/goes down and why
Stereocilia also subject to shearing force but in opposite direction
121
Why does stereocilia bend
Due to hair cells pushed against heavy accessory structure
122
What does bending of hair cells cause
Receptor potential
123
What happens if stereocilia is bent one way
They depolarise, firing rate of action potential increases, basement membrane goes up
124
What happens if stereocilia is bent other way
They hyperpolairse, firing rate of action potential decreases, basement membrane goes down
125
Why do these cells work
Cilia are stuck in accessory structure - if not there - they'd just go up and down - never stimulated
126
What are stereocilia bathed in
Endolymph
127
What happens when stereocilia is bent
Opens K+ channels = K+ enters hair cell down its conc gradient and depolarises it
Depolarisation
128
Summary of depolarisation hair cell
Basement membrane up - cilia bends - opens K+ channels = K+ flows in hair cell - depolarises
129
How are cilia attached
By threads and the bending physically opens up ion channel
130
Role of outer ear
Collects the sound and channels it to the tympanic membrane = vibrates
131
Role of middle ear
Amplifies the sound
| Vibrations from tympanic membrane to oval wind
132
Role of inner ear
Low frequency sound stimulate hair cells distant from the stapes, while high frequency sounds stimulate hair cells close to the stapes. The pattern of hair cells stimulated allows the brain to ‘interpret the sound as any given sound stimulates a specific combination of hair cells.
133
How can sounds be localised
Time of arrival differences
| Intensity differences
134
What is conduction deafness
Sound not conducted to middle of ear, wax, middle ear inflammation, sclerosis of ossicle etc.
135
What is sensineural deafness
damage to neural structures such as hair cell damage, damage to 8th nerve etc.
136
What is sinnitus
Continuous ringing/clicking sound in abscence of auditory stimuli
137
What is the vestibular system
This forms the basis of our sense of balance and acceleration.
138
What is the vestibular system
This forms the basis of our sense of balance and acceleration.
139
What modalities does balance involve
tactile receptors in contact with the floor
vision
but without the information about movement and head position provided by the vestibular system these are insufficient
140
What happens if vestibular system is not working
Can't keep balance
141
Is vestibular system conscious or unconscious
unconscious
142
What does vestibular system control
aspects of our eye movements
143
What does vestibular system tell you
Where head is in space and how head is moving
144
What makes upp vestibular system
The utricle, saccule and semi-circular canals
145
What is structure of vestibular sensory hair cells
The membranous labyrinth of the vestibular system is lined with epithelial cells.
In some areas these cells are modified into sensory hair cells ( receptor cells )
The surface of the hair cells contain cilia, one of which is at the side of the cell and is larger (kinocilium)
The base of the hair
cell joins a sensory neuron
Morphologically and physiologically polarised ( lobsided )
146
What happens if stereocilia are bent towards kinocilium
depolarise, and the afferent firing rate increases.
147
What happens if stereocilia are bent away from kinocilium
kinocilium afferent firing rate decreases
148
When is sensory neuron tonically active
At rest
149
What is meant by physiologically polarised
React differently depending which way you bend cilia
150
What is meant by morphologically polarised
Structurally one side of cell different to other
| the kinocillium is always on the edge of the cell
151
Bid side of cilia
Kinocilium
152
Other side of cilia
Opposite side to kinocillium
153
Where are hair cells in semi - circular canals found
in the ampullae
154
Where do hair cells in semi - circular canals sit
On a ridge/crest
155
What is cilia embedded in
gelatinous cupula (that completely blocks the canal)
156
Where are kinocillia on semi - circular hair cells
On the side facing the vestibule
| side nearest the utricle
157
What fills whole ampullae
Cupula
158
What is bony labyrinth part of and what does that cause
part of the skull, so when the head moves so do the semi-circular canals
159
What happens when head it still
the hair cells are not bent, as the endolymph and skull are not moving
160
What happens when we turn head one way
The semi-circular canals will rotate in the same direction. The endolymph, however, will relatively move in the opposite direction (in fact, due to inertia it stays more or less in the same place). This endolymph will push against the cupula and bend the hair cells
161
What happens if you move head to left
Semi circular canal: to left
Endolymph ( fluid ) to right
They are opposite
The kinocillia in the left semi-circular canal will be bent towards the vestibule (excited), those on the right will be bent away from the vestibule (inhibited).
162
What can CNS determine
From the relative activity of all 6 semi-circular canals the CNS can determine the direction of movement
163
What type of acceleration do semi - circular canals respond to
Angular acceleration
| Not respond to linear motion or constant speed
164
What happens in angular acceleration
With constant rotation the endolymph will catch up with the bony labyrinth and hair cells will no longer be stimulated.
When rotation ceases we get dizzy as relative endolymph movement is reversed.
165
Where are hair cells in vestibule located and what are these areas known as
one area in the utricle and one in the saccule
| Maculae
166
What is utricle and saccule
Two bags in middle of bony labyrinth
167
What directions is macula in saccule
Vertical
168
What direction is macula in utricle
Horizontal
169
What are cilia embedded in
In a dense otolithic membrane = heavy
170
What do kinocilia in macula face
Striola
171
What happens if all hair cells are bent in a given direction
some will be excited and some inhibited.
Different directions of bending will stimulate/inhibit different populations of hair cells
Brain figuire out which way cilia is pushed knowing which hair cells is activated/inhibited
172
What acceleration do otolithic organs respond to
Linear acceleration
173
What happens when you bend head down
Otolithic membrane moves down = bend cilia = depolarisation in some and inhibited in others
174
What acceleration detects gravity
Linear
175
What are causes of vestibular dysfunction
Lesions (either traumatic or by, for example, a tumour or an aneurysm) affecting the 8th cranial nerve. A good example is acoustic neuroma.
Ménière's disease is an idiopathic condition of the inner ear related to endolymph ‘leakage’ (hydrops).
Labyrinthitis is an inflammation of the inner ear following a viral infection
176
When is receptor not a depolarisation
Vertebrate vision
