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Physiology > Sensory organs > Flashcards

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
Q

What are the receptor cells of the olfactory mucosa?

A

Bipolar neurons

The only primary receptor cells of higher organisms

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26
Q

Describe the receptors of the olfactory mucosa

A

Receptor cells project cilia into the mucous layer

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27
Q

What are the thinnest nerve fibres of the body?

A

Myelinated axons leaving the olfactory mucosa

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28
Q
A

Primary olfactory neuron

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29
Q
A

Mitral cells

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30
Q
A

Olfactory bulb

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31
Q
A

Primary olfactory cortex:

  • Amygdala
  • prepyriform area
  • Olfactory tubercle
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32
Q
A

Tufted cell:

Contralateral olfactory bulb

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33
Q

Taste is the reception of…

A

Substances in liquid phase

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34
Q

Function of filiform papillae

A

Mechanoreceptors

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35
Q

Function of fungiform papillae

A

Respond to a stimulus quickly

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36
Q
A

Fossa gustatorica

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37
Q

Give the types of taste combinations

A
  • Sweet
  • Salty
  • Sour
  • Bitter
  • Umami
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38
Q

Glands of Ebner

A
  • Found at the bottom of foliate & circumvallate papillae
  • Serve as quick ‘washing out’ of chemical substances
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39
Q

As well as spatial orientation, light has an impact on…

A

Behaviour & sexual activity

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40
Q

How many colour qualities are distinguished in primates?

A

2 million

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41
Q

For some animals (mainly hunting at night), what is the function of the pigment layer in the eye?

A

Augmentation of light-reflection

Not to absorb light

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42
Q

The phenomenon of increasing the ability or orient in the dark but reducing sharpness of vision

A

Tapetum lucidum

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43
Q

The function of pigment cells

A

Light absorption

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44
Q

Rods + cones functions

A
  • Rods: Light sensitivity
  • Cones: Colour-sensing
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45
Q

The synaptic part of rods + cones is connected to…

A

Bipolar cells

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46
Q

Give the order of the layers of the retina (from the pigment cells)

A
  1. Pigment cells
  2. Rods + cones
  3. Bipolar cells
  4. (Amacrine cells)
  5. Ganglion cells
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47
Q

The fovea of the eye contains…

A

Cones only

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48
Q

The outer segment of rods and cones contains…

A

Light-sensitive pigment

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49
Q

The fovea doesn’t absorb…

A

Blue light

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50
Q

No rods and cones are found in the…

A

Blind spot (Where the optic nerve exits)

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51
Q
A

Rods

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52
Q
A

Cones

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53
Q
A

Blind spot

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54
Q
A

Fovea

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55
Q

Function of the lens

A
  • Refraction of light to be focused on the retina
  • Changes the focal distance
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56
Q

What suspends the lens?

A
  • Suspensory ligaments
  • Circular sphincter muscle
  • Dilator muscle of the pupil
  • Choroid plexus
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57
Q

Function of choroid plexus

A

Secretion of aqueous humour

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58
Q

Physiology behind glaucoma

A
  • Obstruction of the circulation of aqueous humour
  • The increase of intraocular pressure
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59
Q

Give the refraction points of vision

A
  1. Air-cornea
  2. Cornea-aqueous humour
  3. Aqueous humour-lens
  4. Lens-vitrous humour
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60
Q

Diopter

A

The reciprocal of the anterior focal distance given in meters

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61
Q

Images of Purkinje-Sanson

A

Images of light appears on the refractive surfaces of the eye

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62
Q

Beams arriving obliquely from an infinite distance intersect in a plane at the same distance as the…

A

Rear focal plane

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63
Q

To focus on an object at a larger distance, the convexity of the lens should be…

A

Decreased

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64
Q

An eye with perfect accommodation is called…

A

Emmetropic

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65
Q

In the elderly, when the image projects onto the sclera rather than the fovea

A

Hypermetropia

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66
Q

Blurred vision at close sight can be corrected with…

A

A convex lens

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67
Q

Give the steps lens adjustment steps for close vision

A
  1. Ciliary muscle contraction
  2. Ciliary body moves closer to the lens
  3. Reduced tension, lens becomes rounder
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68
Q

Light sensation is triggered in…

A

Rods + cones

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69
Q

In detail give the cellular mechanisms in the light

A
  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
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70
Q

Describe the cellular mechanism of the eye in the dark

A
  • Cones and rods = Dark current
  • Continuous glutamate transmission
71
Q

In detail give the cellular mechanisms in the dark

A
  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
Q

Receptive field

A

AP frequency of ganglion cells depends on illumination state of the retinal section where the ganglion cell receives information

73
Q

Types of ganglion cells in receptive fields

A

On-type and Off-type

74
Q

The exact mapping of an object is made possible by…

A

The centre-periphery structure

  • Cones affect On/Off bipolar cells
  • Ganglion cells react in On/Off mode
75
Q

On-off experiment 1

A
  • Increase of AP frequency in ON cells
  • Cessation AP firing in OFF cells
76
Q

On-Off experiment 2

A
  • Light inhibits resting low-rate AP signalling of the On-type cell
  • Increases that of the Off-type cell
77
Q

On-Off experiment 3

A
  • Light beam overlays the total surface of both ganglion cell types
78
Q

In on-off experiments, activation of both centre and periphery always entails…

A

Reciprocal inhibition

79
Q

On-off experiment 4

A
  • Peripheries of both ganglion types are fully illuminated
80
Q

On-Off experiment 5

A
  • Middle & periphery of both ganglion cell types illuminated equally
  • Reciprocal inhibition causes → low AP frequency
  • Edges of dark/light surfaces represent enhanced stimulus
81
Q

What is needed to code for a colour

A

Several cones

One cone alone cannot code a colour, only light intensity

82
Q

Give the neuronal pairs for receptor cells

A
  • Red-Green
  • Yellow-Blue
  • Black-White
  • Yellow (alone)
83
Q

Scotopic vision

A

Under certain light density, only the rods function

84
Q

Photopic vision

A

Light density is higher, cones are activated

85
Q

Title the figure

A

Luminosity curve

86
Q

Visual field

A
  • Fixed gaze
  • The animal sees only part of the surrounding space
87
Q

The size of the visual field differs for…

A

Each colour

88
Q

Visual acuity

A
  • Sharpness of vision
  • The smallest angle under which two neighbouring object points will still be sensed as two points
89
Q

If there is at least one cone not illuminated between two well illuminated ones…

A

It may give the sensation of two distinguishable points

90
Q

At large distance: Stimulation of two neighbouring cones results in…

A

The sensation of one light spot only

91
Q

Prey animals have a …visual field

A

Monocular

92
Q

Give the order of visual field size by colour, starting with the largest

A

White > blue > green > red

93
Q

How is spatial vision provided?

A
  • 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
Q

Saccadic movement

A
  • Small changes in eye position
  • Used for ‘scanning’ a viewed object
95
Q

A single oculomotor neuron innervates…

A

2-3 eye muscle fibres

96
Q

Conjugated eye movement

A

The axes of two eyes move together

97
Q

Vergeance movement

A

Divergence/Convergence

98
Q

Cycle-rotational movement

A
  • If the head tilts during fixation
  • Compensatory movements
99
Q

Title the figure

A

Object movement relative to 0° position

100
Q
A
  • Gaze
  • Eye
101
Q
A

Head

102
Q
A

Gaze

103
Q
A

Head

104
Q
A

Eye

105
Q

During object tracking, after correction of the head position…

A

The eye quickly adapts tot he new position

106
Q

The shape of a dilated pupil is always

A

Circular

107
Q

Describe the innervation of the pupil reflexes

A
  • Muscle for constriction : Parasympathetic control
  • Muscle for dilation : Sympathetic control
108
Q

Myosis

A

Pupil constriction

109
Q

Mydriasis

A

Dilation of the pupil

110
Q

Describe the consensual reaction of pupil dilation

A
  • As light causes one pupil to constrict
  • The other eye will constrict without light needed
111
Q

What dilates the pupil

A

Pain/ fight or flight

112
Q

Which Brodmann area is the primary visual area?

A

17

113
Q

The temporal and nasal parts of the visual field project…

A

To the opposite sides of the retina

  • The dorsal and ventral parts are reversed in the same way
114
Q
A

Nasal & temporal halves of retina

115
Q
A

Optic chiasm

  • Fibres of the nasal part of the retina decussate
116
Q

The optic tract is formed by…

A
  • A smaller medial bundle
  • A larger lateral bundle
117
Q

The medial bundle of the optic tract

A

Reaches superior colliculus

Important in visual reflexes

118
Q

Pretectum

A

Midbrain structure

Involved in:

  • Pupillary light reflex
  • Optokinetic reflex
  • Temporary changes to circadian rhythm
119
Q

Superior colliculus function

A

Integrates saccadic eye movement

Localisation of an object

120
Q

LGN

A

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
Q

Optic radiation

A

In the medial part of the occipital lobe

  • Information is transmitted to the visual cortex by radiation
122
Q

Primary visual cortex

A
  • Striated cortex
  • Neuronal columns
  • Cylinders for colour vision
123
Q

The function of orientation columns

A

Identify special patterns

  • By use of the contrast effect
124
Q

Mammals have better hearing…than humans

A

Frequency

125
Q

Sound is characterised by…

A

Wavelength + amplitude

126
Q

Sound velocity is constant…

A

In a given medium at a given temperature

127
Q

Sound output is in which units?

A

Decibels/bels

128
Q

Two sounds with different frequencies arent sensed with…

A

Equal intensity

129
Q

Phon scale

A

Used to measure psychophysical characteristics of sound output ratio

130
Q

Sounds with 1000Hz frequency have equal…

A

Values on the phon and bel scale

131
Q

The oval window pushes into the…

A

Scala vestibuli

132
Q

Describe amplification from the external to the internal ear

A

22-fold amplification

133
Q

Which muscles contract to protect the ear from damaging sound?

A
  • M. tensor tympanii
  • Innervated by the trigeminal nerve*
  • M. stapedius

Innervated by the facial nerve

134
Q
A

Scala vestibuli

  • Containing perilymph
135
Q
A

Scala tympani

  • Containing perilymph
136
Q
A

Scala media

  • Containing endolymph
137
Q
A

Helicotrema

138
Q
A

Organ of Corti

139
Q
A

Tectorial membrane

140
Q
A

Reissner’s membrane

141
Q
A

Basilar membrane

142
Q

The receptor cells of the organ of corti

A

Hair cells

143
Q

What leads to the excitation of hair cells?

A
  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
Q

Lower frequency sounds travel to the…part of the cochlea

A

Helicotrema (apex)

145
Q

0

A

Displacement of mechanosensitive cation channels

146
Q

1

A

Depolarising potassium current

Depolarisation

147
Q

2

A

Voltage dependent calcium channel opens:

Calcium influx

148
Q

3

A

Calcium sensitive basolateral potasium channel opens

K+ efflux

149
Q

4

A

Hyperpolarisation/Repolarisation

150
Q

5

A

Calcium sequestration

151
Q

6

A

Oscillation membrane potential amplification

152
Q

7

A

Glutamate transmission

153
Q

The sensitivity of hearing can be tuned by…

A

The CNS

154
Q

Organ of Corti

A
155
Q
A

Cochlear ganglion

156
Q
A

Dorsal olivary nucleus

157
Q
A

Medial lemniscus

158
Q
A

Ventral colliculus

159
Q
A

Thalamus CGM

160
Q
A

Primary auditory cortex

161
Q

As the cochlear ganglion is innervated, the neural signal is transferred to which two cell types?

A
  • Stellate cells
  • Bushy cells

Generates a time mark, allowing spatial orientation by sound

162
Q

Lesion of the central units of the auditory tract…

A

Never produces unilateral hearing disorders

163
Q

Vestibular apparatus

A

Provides spatial position and motion of the head

  • Generates both static and kinetic information
164
Q

The vestibular organ is filled with…

A

Endolymph

165
Q

Name the enlargements of the vestibular semicircular ducts

A
  • Ampulla
  • Utricle
  • Saccule
166
Q

The canals of the vestibular apparatus are arranged so that…

A

Each canal on the left side has an almost parallel counterpart on the right

167
Q

In the vestibular organ, the movement of fluid pushes…

A

On the cupula

  • Containing hair cells, transducing mechanical movements to electrical signals
168
Q

Movement of vestibular hair cells in the opposite direction to the depolarising direction causes…

A

Hyperpolarisation

169
Q

Vestibular apparatus: Depolarisation causes neurotransmitter release on the other pole of the sensory epithelium, this stimulates…

A

The primary afferent nerve-ending

170
Q

Afferent fibres from the vestibular organ travel to the…

A

Cerebellum

171
Q

Otolith crystals function

A

Vestibular apparatus: Push/pull the cilia of the hair cells

Therefore the receptor only responds to static effects and liner acceleration

172
Q

When stereocilia bend toward the kinocilium…

A
  1. Mechanosensitive K+ channels open → Depolarisation
  2. IC Ca2+ signal triggers emptying of neurotransmitter
  3. AP generation
173
Q

Title the figure

A

Turning of the head (left)

Physiology (18 decks)

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