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Sensory organs Flashcards

1
Q

Increasing the amplitude of a stimulus increases…

A

The frequency of action potentials of the afferent fibres

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2
Q

Modality

A

A particular form of sensory perception

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3
Q

Give the classifications of receptors according to: Receptor

A
  • Primary
  • Secondary
  • Tertiary
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4
Q

Give the classifications of receptors according to: Localisation of stimulus

A
  • Exteroceptors
  • Interoceptors
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5
Q

Give the classifications of receptors according to: Form of energy of the stimulus

A
  • Mechanical
  • Thermal
  • Photo
  • Chemical
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6
Q

Give the classifications of receptors according to: Type of perception (modality)

A
  • Touch
  • Warm
  • Cold
  • Pain
  • Light
  • Sound
  • Taste
  • Smell
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7
Q

Give the classifications of receptors according to: Adaptation

A
  • Fast (Dynamic/phasic)
  • Slow (Tonic/static)
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8
Q

Primary receptor

A

Stimulus elicits a direct conformational change to the channels of the neuron

E.g Olfaction

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9
Q

Secondary receptor

A

Stimulus is sensed by the second cell of sensation, cation channels then open

E.g sound reception: 1. hair cell, 2. auditory nerve

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10
Q

Tertiary receptor

A

Afferent nerve fibre belongs to only the third cell involved in stimulus transduction

E.g 1. Rods + cones, 2. Bipolar cells, 3 Ganglion cells

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11
Q

Give the types of receptor

A
  • Free nerve ending
  • Pacinian corpuscle
  • Golgi tendon organ
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12
Q

Give an example of an exteroceptor

A

Pain/temperature receptors of the skin

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13
Q

Pacinian corpuscle

A

Member of the exteroceptors functioning by no free nerve endings

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14
Q

Golgi tendon organ location

A
  • Found at the border of the tendon and muscle
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15
Q

Why are receptors also known as transducers?

A

Mechanical stimulus may evoke an electric response

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16
Q

Generator potential is conducted with…

A

Decrement/possible information loss

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17
Q

Information that has been transformed

A
  • Travels at a high speed
  • Frequency coded manner
  • Safer
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18
Q

Give the temp/AP frequency relationship

A
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19
Q

Title the figure

A

Skin temp. and AP frequency in various fibres

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20
Q
A

Skin temperature

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21
Q
A

Cold fibre

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22
Q
A

Warm fibre

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23
Q

Heat is sensed by what kind of system?

A

Dual receptor system

  • Warm receptors (receptive between 30-45°C)
  • Cold receptors (receptive between 15-42°C)
  • 2x more cold receptors than warm
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24
Q

What is unique about olfaction?

A
  • Fast adaptation to stimuli
  • High differential threshold
  • Difficulty in locating the source
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25
What are the receptor cells of the olfactory mucosa?
Bipolar neurons ## Footnote *The only primary receptor cells of higher organisms*
26
Describe the receptors of the olfactory mucosa
Receptor cells project cilia into the mucous layer
27
What are the thinnest nerve fibres of the body?
Myelinated axons leaving the olfactory mucosa
28
Primary olfactory neuron
29
Mitral cells
30
Olfactory bulb
31
Primary olfactory cortex: * Amygdala * prepyriform area * Olfactory tubercle
32
Tufted cell: Contralateral olfactory bulb
33
Taste is the reception of...
Substances in _liquid_ phase
34
Function of filiform papillae
Mechanoreceptors
35
Function of fungiform papillae
Respond to a stimulus _quickly_
36
Fossa gustatorica
37
Give the types of taste combinations
* Sweet * Salty * Sour * Bitter * Umami
38
Glands of Ebner
* Found at the bottom of foliate & circumvallate papillae * Serve as quick 'washing out' of chemical substances
39
As well as spatial orientation, light has an impact on...
Behaviour & sexual activity
40
How many colour qualities are distinguished in primates?
2 million
41
For _some_ animals (mainly hunting at night), what is the function of the pigment layer in the eye?
Augmentation of light-reflection ## Footnote *Not to absorb light*
42
The phenomenon of increasing the ability or orient in the dark but reducing sharpness of vision
Tapetum lucidum
43
The function of pigment cells
Light absorption
44
Rods + cones functions
* Rods: Light sensitivity * Cones: Colour-sensing
45
The synaptic part of rods + cones is connected to...
Bipolar cells
46
Give the order of the layers of the retina (from the pigment cells)
1. Pigment cells 2. Rods + cones 3. Bipolar cells 4. (Amacrine cells) 5. Ganglion cells
47
The fovea of the eye contains...
Cones only
48
The outer segment of rods and cones contains...
Light-sensitive pigment
49
The fovea doesn't absorb...
Blue light
50
No rods and cones are found in the...
Blind spot (Where the optic nerve exits)
51
Rods
52
Cones
53
Blind spot
54
Fovea
55
Function of the lens
* Refraction of light to be focused on the retina * Changes the focal distance
56
What suspends the lens?
* Suspensory ligaments * Circular sphincter muscle * Dilator muscle of the pupil * Choroid plexus
57
Function of choroid plexus
Secretion of aqueous humour
58
Physiology behind glaucoma
* Obstruction of the circulation of aqueous humour * The increase of intraocular pressure
59
Give the refraction points of vision
1. Air-cornea 2. Cornea-aqueous humour 3. Aqueous humour-lens 4. Lens-vitrous humour
60
Diopter
The reciprocal of the anterior focal distance given in meters
61
Images of Purkinje-Sanson
Images of light appears on the refractive surfaces of the eye
62
Beams arriving obliquely from an infinite distance intersect in a plane at the same distance as the...
Rear focal plane
63
To focus on an object at a larger distance, the convexity of the lens should be...
Decreased
64
An eye with perfect accommodation is called...
Emmetropic
65
In the elderly, when the image projects onto the sclera rather than the fovea
Hypermetropia
66
Blurred vision at close sight can be corrected with...
A convex lens
67
Give the steps lens adjustment steps for close vision
1. Ciliary muscle contraction 2. Ciliary body moves closer to the lens 3. Reduced tension, lens becomes rounder
68
Light sensation is triggered in...
Rods + cones
69
In detail give the cellular mechanisms in the light
1. 11-cis-retinal absorbs light 2. 11-cis-retinal → 11-_trans_-retinal 3. 11-trans-retinal → Metaretinal 4. G-protein activated 5. Cation channels closed 6. Hyperpolarisation of the cell 7. Glutamate transmitter release ceases
70
Describe the cellular mechanism of the eye in the dark
* Cones and rods = Dark current * Continuous glutamate transmission
71
In _detail_ give the cellular mechanisms in the dark
1. Inactive membrane discs 2. cGMP keeps the Na+ channels open 3. Na+ flows into the cell continuously 4. Dark current for rods + cones emerges 5. Generation of sustained glutamatergic transmission 6. Glutamate inhibits bipolar cells, depolarising some cells, hyperpolarising others
72
Receptive field
AP frequency of ganglion cells depends on illumination state of the retinal section where the ganglion cell receives information
73
Types of ganglion cells in receptive fields
On-type and Off-type
74
The exact mapping of an object is made possible by...
The centre-periphery structure * Cones affect On/Off bipolar cells * Ganglion cells react in On/Off mode
75
On-off experiment 1
* Increase of AP frequency in _ON_ cells * Cessation AP firing in _OFF_ cells
76
On-Off experiment 2
* Light inhibits resting low-rate AP signalling of the _On_-type cell * Increases that of the _Off_-type cell
77
On-Off experiment 3
* Light beam overlays the total surface of both ganglion cell types
78
In on-off experiments, activation of both centre and periphery always entails...
Reciprocal inhibition
79
On-off experiment 4
* Peripheries of both ganglion types are fully illuminated
80
On-Off experiment 5
* Middle & periphery of both ganglion cell types illuminated _equally_ * Reciprocal inhibition causes → low AP frequency * Edges of dark/light surfaces represent enhanced stimulus
81
What is needed to code for a colour
_Several_ cones ## Footnote *One cone alone cannot code a colour, only light intensity*
82
Give the neuronal pairs for receptor cells
* Red-Green * Yellow-Blue * Black-White * Yellow (alone)
83
Scotopic vision
Under certain light density, only the rods function
84
Photopic vision
Light density is higher, cones are activated
85
Title the figure
Luminosity curve
86
Visual field
* Fixed gaze * The animal sees only part of the surrounding space
87
The size of the visual field differs for...
Each colour
88
Visual acuity
* Sharpness of vision * The smallest angle under which two neighbouring object points will still be sensed as two points
89
If there is at least one cone not illuminated between two well illuminated ones...
It may give the sensation of two distinguishable points
90
At large distance: Stimulation of two neighbouring cones results in...
The sensation of one light spot only
91
Prey animals have a ...visual field
Monocular
92
Give the order of visual field size by colour, starting with the largest
White \> blue \> green \> red
93
How is spatial vision provided?
* Points are located on the same spherical surface as the fixation point * Points located in front/behind the spherical surface don't do so * Small distortion * Sensed as distance
94
Saccadic movement
* Small changes in eye position * Used for 'scanning' a viewed object
95
A single oculomotor neuron innervates...
2-3 eye muscle fibres
96
Conjugated eye movement
The axes of two eyes move together
97
Vergeance movement
Divergence/Convergence
98
Cycle-rotational movement
* If the head tilts during fixation * Compensatory movements
99
Title the figure
Object movement relative to 0° position
100
* Gaze * Eye
101
Head
102
Gaze
103
Head
104
Eye
105
During object tracking, after correction of the head position...
The eye quickly adapts tot he new position
106
The shape of a dilated pupil is always
Circular
107
Describe the innervation of the pupil reflexes
* Muscle for constriction : Parasympathetic control * Muscle for dilation : Sympathetic control
108
Myosis
Pupil constriction
109
Mydriasis
Dilation of the pupil
110
Describe the consensual reaction of pupil dilation
* As light causes one pupil to constrict * The other eye will constrict without light needed
111
What dilates the pupil
Pain/ fight or flight
112
Which Brodmann area is the primary visual area?
17
113
The temporal and nasal parts of the visual field project...
To the opposite sides of the retina * The dorsal and ventral parts are reversed in the same way
114
Nasal & temporal halves of retina
115
Optic chiasm * Fibres of the nasal part of the retina decussate
116
The optic tract is formed by...
* A smaller medial bundle * A larger lateral bundle
117
The medial bundle of the optic tract
Reaches superior colliculus Important in _visual reflexes_
118
Pretectum
Midbrain structure Involved in: * Pupillary light reflex * Optokinetic reflex * Temporary changes to circadian rhythm
119
Superior colliculus function
Integrates saccadic eye movement Localisation of an object
120
LGN
Lateral geniculate nucleus * Located in the thalamus * Functions as a filter * Doesn't allow certain parts of retinal stimuli pass to higher cortical areas
121
Optic radiation
In the medial part of the occipital lobe * Information is transmitted to the visual cortex by radiation
122
Primary visual cortex
* Striated cortex * Neuronal columns * Cylinders for colour vision
123
The function of orientation columns
Identify special patterns * By use of the contrast effect
124
Mammals have better hearing...than humans
Frequency
125
Sound is characterised by...
Wavelength + amplitude
126
Sound velocity is constant...
In a given medium at a given temperature
127
Sound output is in which units?
Decibels/bels
128
Two sounds with different frequencies arent sensed with...
Equal intensity
129
Phon scale
Used to measure psychophysical characteristics of sound output ratio
130
Sounds with 1000Hz frequency have equal...
Values on the phon and bel scale
131
The oval window pushes into the...
Scala vestibuli
132
Describe amplification from the external to the internal ear
22-fold amplification
133
Which muscles contract to protect the ear from damaging sound?
* M. tensor tympanii * Innervated by the trigeminal nerve* * M. stapedius Innervated by the facial nerve
134
Scala vestibuli * Containing perilymph
135
Scala tympani * Containing perilymph
136
Scala media * Containing endolymph
137
Helicotrema
138
Organ of Corti
139
Tectorial membrane
140
Reissner's membrane
141
Basilar membrane
142
The receptor cells of the organ of corti
Hair cells
143
What leads to the excitation of hair cells?
1. Displacement of the basilar membrane 2. Hair cells touch the tectorial membrane 3. Excitation of the hair cells 4. Axons travel down the acoustic nerve
144
Lower frequency sounds travel to the...part of the cochlea
Helicotrema (apex)
145
0
Displacement of mechanosensitive cation channels
146
1
Depolarising potassium current Depolarisation
147
2
Voltage dependent calcium channel opens: Calcium influx
148
3
Calcium sensitive basolateral potasium channel opens K+ efflux
149
4
Hyperpolarisation/Repolarisation
150
5
Calcium sequestration
151
6
Oscillation membrane potential amplification
152
7
Glutamate transmission
153
The sensitivity of hearing can be tuned by...
The CNS
154
Organ of Corti
155
Cochlear ganglion
156
Dorsal olivary nucleus
157
Medial lemniscus
158
Ventral colliculus
159
Thalamus CGM
160
Primary auditory cortex
161
As the cochlear ganglion is innervated, the neural signal is transferred to which two cell types?
* Stellate cells * Bushy cells Generates a time mark, allowing spatial orientation by sound
162
Lesion of the central units of the auditory tract...
Never produces unilateral hearing disorders
163
Vestibular apparatus
Provides spatial position and motion of the head * Generates both static and kinetic information
164
The vestibular organ is filled with...
Endolymph
165
Name the enlargements of the vestibular semicircular ducts
* Ampulla * Utricle * Saccule
166
The canals of the vestibular apparatus are arranged so that...
Each canal on the left side has an almost parallel counterpart on the right
167
In the vestibular organ, the movement of fluid pushes...
On the cupula * Containing hair cells, transducing mechanical movements to electrical signals
168
Movement of vestibular hair cells in the opposite direction to the depolarising direction causes...
Hyperpolarisation
169
Vestibular apparatus: Depolarisation causes neurotransmitter release on the other pole of the sensory epithelium, this stimulates...
The primary afferent nerve-ending
170
Afferent fibres from the vestibular organ travel to the...
Cerebellum
171
Otolith crystals function
Vestibular apparatus: Push/pull the cilia of the hair cells Therefore the receptor only responds to static effects and liner acceleration
172
When stereocilia bend toward the kinocilium...
1. Mechanosensitive K+ channels open → Depolarisation 2. IC Ca2+ signal triggers emptying of neurotransmitter 3. AP generation
173
Title the figure
Turning of the head (left)

Physiology (18 decks)

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