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Structure And Function Of Living Organisms > Comparative sensory physiology > Flashcards

Comparative sensory physiology Flashcards

1
Q

What are photoreceptors

A

cells that contain molecules (opsins) which absorb photons in their external membrane. Absorb light

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2
Q

How can photoreceptors increase efficiency of trapping light

A

the cell is expanded into discs or finger like rods. More membrane, the more receptive you are to light

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3
Q

Vertebrate rods and cones

A

has photoreceptive opsin molecules. Stacked discs. Connecting cilum. Light is hyperpolarised

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4
Q

Invertebrate retinula cells

A

cell body. Rhabdomere formed by microvilli. Light depolarises

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5
Q

Vertebrate eye

A

Cornea - 70% of focusing power.
Lens - 30% of focus
Photoreceptors around outside.
Optic disc (blind spot). Optic nerve

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6
Q

Why do we have discs in the eye

A

Opsins are membrane bound so having the discs greatly increase their number in each photorector greatly improving light trapping efficiency.

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7
Q

Are cones or rods more responsive to light

A

rods

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8
Q

Are rods colour sensitive

A

no

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9
Q

Why do rods remain active at low light levels

A

Rods have more discs and so more opsin – containing membrane in the outer segment

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10
Q

How are Na+ and Ca2+ channels kept open in the dark

A

by high levels of cGMP

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11
Q

Depolarization of photoreceptors

A

increases transmitter release - do not produce action potentials

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12
Q

What does light activate

A

Transducin to break down cGMP into GMP

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13
Q

What do low levels of cGMP cause

A

ion channels to close, hyperpolarising the cell and reducing transmitter release

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14
Q

What are4 the 4 photoreceptors

A

blue cones, green cones, red cones and rods

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15
Q

Which photoreceptor is active at low light levels

A

rods - we have no colour perception

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16
Q

Colour perception in bright light

A

sensitive to red, green and blue light (trichromatic vision)

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17
Q

Which animals have no visual processing in their forebrain

A

reptiles, amphibians and fish because they have small rudimentary forebrains

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18
Q

Where does visual processing take place in reptiles etc

A

in the visual part of the mid brain (the optic tectum)

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19
Q

Visual area in the midbrain in mammals

A

involved in visual reflexes, turning to look at new objects appear in the visual fields

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20
Q

Lens in the eye for a bird

A

has a foveal base which acts to create a telephoto system. Visual activity in the medial fovea is 2-3 x that of a man

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21
Q

Avian vision

A

medial fovea - side vision. Retina and a fovea

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22
Q

What is the problem with avian vision

A

when the bird dives the head faces forward but the visual axis of the telephoto system is at 40 degrees to the direction of flight - turning head increases drag. Their solution is to fly along a curved flight path to keep prey image in the medial fovea

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23
Q

In invertebrates what does light activate

A

phopholipase C to break down PIP2 to IP3 and DAG. This opens ion channels causing photorecptor to depolarise (no action potentials)

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24
Q

Photoreceptors in polychaete (marine worm) and in a flat worm

A

rhabdome, pigment cell

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25
Q

photoreceptor in cnidarian (box jelly fish)

A

cornea, lens, pigment cell, rhabdome, pigment granules

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26
Q

What are compound eyes made up of

A

photoreceptor units each with its own lens (may vary in sensitivity)

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27
Q

What does the shape of compound eyes allow for

A

bulbous shape provides all round vision

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28
Q

Compound eyes - fossil recording

A

First appeared in fossil recording early predators such as the 500 million year old (pre-Cambrian) Anomalocaris found in deposits in Kangaroo Island, Australia and the Burgess shales in Canada

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29
Q

What is the optical unit that makes up the compound eye

A

ommatidium

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30
Q

Ommatidium structure

A

lens, pigment cells, photoreceptors (R1-8), rhabdomeres

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31
Q

What can central rhabdomeres sometimes be sensitive to

A

UV light

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32
Q

What light is detected in compound eyes

A

light polarised parallel to the direction microvilli is detected

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33
Q

What do the outer rhabdomeres (1-6) detect

A

the direction of the microvilli

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34
Q

Microvilli in the central rhabdomeres (7 lies on top of 8)

A

microvilli only run in one direction so they are sensitive to light polarisation. This aids navigation as the light is polarised in concentric circles around the sun

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35
Q

What do flowers pollinated from these insects usually have

A

patterns visible in UV light that guide them to the source of nectar and pollen (co-evolution)

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36
Q

Why do flies have limited behavioural repetoire

A

Computational resources in the invertebrate nervous system are limited have – e.g., the fly brain contains only around 250,000 neurones

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37
Q

What can the fly visual system also recognise

A
  1. Movement (which may indicate danger or mating displays)
  2. Looming (approaching) objects e.g., for collision avoidance when flying
  3. Visual field slippage – indicates movement relative to the ground an also turning
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38
Q

Simple eyes (ocelli) features

A

smaller than compound eyes. Many receptors under a single lens

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39
Q

Hunting spiders simple eye distribution

A

distributed around the head to provide a wide field of view

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40
Q

What do insects with simple eyes usually have

A

have 3 simple eyes arranged in a triangular patten. When flying, these eyes act as a horizon detector so that the insect can maintain a stable flight path

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41
Q

What can Cephalopods (octopus/squid) do

A

They can change their skin colour patterns and texture rapidly for camouflage and signalling

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42
Q

Cuttle fish visual subterfuge

A

The male is displaying to the female to encourage her to mate. The side of his body facing her shows male patterning. This could attract rival males who would try to compete with him for the female. So on the side of his body away from the female he shows female patterning

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43
Q

Infra-red vision in snales

A

detect heat. Part of the somatosensory system and does not recieve signals from their eyes. Works because of the snakes low body temperature so receptor is kept cool

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44
Q

Where is visual processing carried out in snakes

A

in the mid brain optic tectum because the forebrain is primitive

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45
Q

How are the 2 types of information superimposed for snake infra-red vision

A

because the infrared vision of the pit organs also maps onto the optic tectum

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46
Q

Which other animals also have information overlap in the optic tectum

A

Owls, in their auditory and visual maps. Done so their fine directional hearing arguments visual input which may be poor at night

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47
Q

How does the pit organs work

A

The receptor (TRPA1) is like the one in our skin and mouth that detects both noxious heat and chemical heat sensation e.g., chilli powder (caoaicin)

In rattle snakes this becomes sharply active at 28 degrees

Rat snakes does not have effective infrared ‘vision’

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48
Q

Parts of the ear

A

pinna, external ear cannal, ear drum, nerves

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49
Q

What does the pinna do

A

causes vibration of the ear drum, critical in the transduction.

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50
Q

Where does transduction take place

A

cochlea

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51
Q

How is sound detected

A

. Sound is initially detected because it sets up vibrations in the eardrum (tympanic membrane) and amplified by the movement of the ear ossicles in the middle ear

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52
Q

Frequency analysis in the cochlea

A

High frequency selected at the base, lower frequency at the apex.

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53
Q

where are cilia present in the ear

A

against tectorial membrane

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54
Q

What does sound cause the basilar membrane to do

A

causes it to vibrate, causing seterocilia to push against tectorial membrane. Hair cell activates auditory nerve

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55
Q

What does how far the wave travels depend on

A

the frequency

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56
Q

insec4t hearing - function of the tympanum

A

its a thin cuticle that plays the same role as the eardrum in the vertebrates that vibrates more than normal cuticle

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57
Q

What calls fo bats use for navigation and catching prey

A

echolocating calls

58
Q

Bat call frequencies

A

25-100 kHz

59
Q

What do moths use auditory systems for

A

to detect predators and take evasive action

60
Q

What can bats detect when hunting

A

can detect insect wing movement as well as judging how far away they are (size, species)

61
Q

What do male mosquitos use hearing for

A

to find/detect females by the humming of their wing beats

62
Q

What does the antenna do

A

resonates at the female wingbeat frequency (360-400 Hz)

63
Q

How do mosquitos detect airbourne vibrations

A

detected by Johnston;s organ at the base of the antenna. Active processes in the sensory neurones amplify the signal making it extremely sensitive at this frequency

64
Q

What is olfaction

A

smell

65
Q

What is gustation

A

taste

66
Q

Insect v vertebrate hearing - complexity

A

insects do a few things well and have a simple nervous system. Vertebrates have a more complex nervous system and have more flexibility

67
Q

Insect v vertebrate hearing - detecting vibrations

A

insects detect vibration with a membrane or appendage (antenna/leg). Vertebrates detect them by a tympanic membrane

68
Q

Insect v vertebrate hearing - amplification

A

insects amplify through active responses of sensory dendrites. Vertebrates have several amplification stages (external hera, ossicles, cochlear amplifier)

69
Q

Insect v vertebrate hearing - tonotopic representation of frequency

A

insects only rarely present in CNS. vertebrates represent at many levels of the CNS

70
Q

Insect v vertebrate hearing - importance of sound detection

A

important for insect behaviour (specifc, simple and few signals). Vertebrates also important for behaviour but is more complex

71
Q

Insect v vertebrate hearing - detecting subsonic vibration

A

important for insect but usually via ahirs, appendages (antennae, cerci). Present in vertebrates (pacinian corpuscles, lateral line organs in fish contain hair cell receptors)

72
Q

5 types of taste sensation

A

sweet, salt, bitter, sour (acid), umami (glutamate)

73
Q

What does sweet taste indicate

A

indicates source of energy and ripeness (fruit)

74
Q

What does a bitter taste indicate

A

poisonous plants/fruits/insects

75
Q

What does a sour taste indicate

A

spoilage of foodstuffs

76
Q

What is an umami taste

A

‘meaty’ taste (MSG)

77
Q

What causes other aspects of flavour

A

olfaction

78
Q

Taste cell for salt and acid

A

have Na+ and H+ channels. They depolarise the cell, opening Ca2+ channel and triggering neurotransmitter release

79
Q

Taste cell for bitter, sweet and umami

A

Have g-protein coupled receptors that bind to molecules causing ion channels to open, thus triggering transmitter release

80
Q

olfactory transduction on olfactory neuron ciliary membrane

A

Odour molecule bind causing a g protein subunit to stimulate adenylyl cyclase (amplification). This increases levels of cAMP which opens ion channels in the cell membrane causing it to depolarise which causes an action potential to be generated

81
Q

Odour receptor genes in mammals

A

Mammals have up to 1000 odour receptor genes that allow discrimination of around 10,000 odours

82
Q

sensory transduction - invertebrates

A

ion channel is opened (gated) by binding an odour molecule

83
Q

sensory transduction - invertebrates

A

ion channel is opened (gated) by binding an odour molecule

83
Q

sensory transduction - invertebrates

A

ion channel is opened (gated) by binding an odour molecule

84
Q

Where is the chemosensory receptor located in an invertebrate

A

on the outer membranes of the cilia

85
Q

Structure of a chemosensory hair

A

pore, cehmosensory dendrite, cuticle, epidermal cell, mechanosensory dendrite, chemosensory neurones, axon

86
Q

What are pheromones

A

molecules released by one sex to attract the other e.g., moths. Pheromone receptors can be activated by a single molecule

87
Q

What are on antennas

A

have a range of different sensory hairs not only olfactory, but also very long fine hairs (airflow) and shorter hairs (tactile) to pick up odours

88
Q

Where do sensory neurons have processes

A

in the skin/ muscle (tendons/joints), that run into spinal cord cell bodies in the dorsal root ganglia

89
Q

What do sensory neurons give information on

A

temperature, pain, touch, muscle length/tension to help pick up something

90
Q

what is exteroception

A

touch, temperature and pain from external stimuli

91
Q

what is proprioception

A

inside the body like at muscles, tendons and visceral organs

92
Q

what are exteroceptors

A

sensory endings that monitor interactions with external environment

93
Q

what do glial cells do

A

encapsulate nerve endings below the surface and modify properties

94
Q

what type of sensation does a naked ending sensory ending detect

A

pain, temperature

95
Q

what type of sensation does a hair follicle ending sensory ending detect

A

hair movement

96
Q

what type of sensation does a Merkel’s ending (dense on finger pads)sensory ending detect

A

sustained pressure - detailed mapping oof texture and shape (slow adapting)

97
Q

what type of sensation does a Melssner’s ending sensory ending detect

A

touch - brief response, effective for transient contact (rapid adapting)

98
Q

what type of sensation does a pacinian corpsucle ending sensory ending detect

A

vibration

99
Q

what type of sensation does a ruffini ending sensory ending detect

A

shear stress

100
Q

How are axons sent

A

sent to different ascending tracts (spinal cord to brain) via thalamus project to primary sensory cortex

101
Q

Which two tracts can do similar jobs in different species

A

spinothalamic or spinocervical

102
Q

What is the primary somatosensory cortex involved in

A

involved in sensation, proprioception goes there and to the cerebellum

103
Q

What are proprioreceptors

A

receptors monitoring muscles and joints. Within muscle fibres , to produce the power, there are small spindle shaped structures whose length is monitored by sensory and controlled by motor, Specialized, intrafusal muscle fibres. Spindle – like. Grain of wheat. Power is extrafusal.

104
Q

What are the 3 proprioreceptors

A

muscle spindles, golgi tendon organs, joint receptors

105
Q

How do muscle spindles work

A

When the muscle is stretched, the sensory axon in the spindle responds. When the signal reaches the spinal cord, the alpha motorneurons contract the muscle – this may make the spindle slack so it cannot respond to further stretch. So gamma motor neurons fire and the spindle contracts, restoring its responsiveness. Necessary to transmit sensation and keep the system responsive

106
Q

What controls extrafusal fibres

A

alpha motorneurons

107
Q

What control intrafusal fibres

A

gamma motor neurons

108
Q

What do golgi tendon organs monitor

A

stretch in tendons, endings sit in tendons

109
Q

where does our awareness for the relative positions of different parts of the body come from

A

the activity of the muscle spindles plus the Golgi tendon organs

110
Q

Joint receptors

A

These endings in the capsule and the supporting ligaments of joints give sensations of pain and discomfort when the joint is moved beyond its range of normal movement. Not indicative if just their positions but more their normal range.

111
Q

example of exteroceptor in invertebrates

A

Touch/wind sensitive hairs on exoskeleton (trichoid sensillum - “thread like”). Q

Air movement – necessary to flap its wings

112
Q

What is the sensory hair in invertebrates like

A

quite stiff. Some less stiff are much longer, flexible socket, allow to move. Short – contact

113
Q

What is underneath the sensory hair in invertebrates

A

have sensory neuron. Contain a modified cilia. Monitors movement. Support cells make up a little package. Action potential then runs to the central nervous system

114
Q

In animals with exoskeletons what mediates exteroception

A

mechanosensory hairs. These detect not only touch but also air currents and are therefore also important in maintaining flight movements

115
Q

Somatotropy in insects

A

ganglian for each segment. Thorax, 3 legs, 2 pairs of wings. There are maps; 3 ganglions refer to 3 legs and also possibly a wing on each.

116
Q

What are campaniform sensillae (wasps)

A

depressions with a floor of very thin cuticle which monitor distortion (loading) of the insect exoskeleton. They buckle under pressure. Under each is a sensory neuron, they are triggered by deformation and fire action potentials.

117
Q

External structures in wasps for detection

A

insect hair plates and campaniform sensilla

118
Q

Stings from wasps

A

As the femur rotates upwards, its surface contacts the hair plate on the coxa indicating that it can travel no further. This fulfils the same role as vertebrate joint receptors.

Sting apparatus from the wasp, tells whether sting retracted or pushed out. Joint on the end of the abdomen on wasp. Sting extended, hairs extended. As ting is withdrawn long hairs pressed down

119
Q

What modifies the hind wings in insects

A

haltere, tell you if its turning and monitors movement of the cuticle

120
Q

How of the oscillating halteres work (insects)

A

act like gyroscopes as they tend to resist changes in the direction of their movement. When the insect turns during flight this creates strains in the shaft of each haltere that are detected by the arrays of campaniform sensillae that lie at its base (detect deformation as animal rotates)

121
Q

What is at the end of halteres

A

Have a mass on the end, very thin stalk, move up and down out of phase with wings. Same frequency as wing beat

122
Q

What is the chordotonal organ (insect proprioception)

A

This lies inside the exoskeleton and is a stretch receptor which has its own tendon, here attached to the fibia crossing joint.

123
Q

What does the chordotonal organ do when the joint is flexed

A

different sensory neurons detect the position of the joint and the speed of the movement

A group of sensory neurons that respond differently – some slow, some large movement

124
Q

What does the chordotonal organ give information about

A

movement, detect position of the joint and speed of movement

125
Q

What form muscle receptor organs (crustaceans)

A

Formed from small accessory muscles that are supplied by the same nerve cells that control the power muscles (I.e., in parallel)

126
Q

What is the muscle receptor organ analogous to (crustacean)

A

the muscle spindle

127
Q

What movements does the muscle receptor organ monitor

A

powerful tail flips that are used for escape. DO NOT provide movement

128
Q

Muscle receptor organs - what ae the sensors attached to

A

special muscle fibres, which adjust the length of these to be put in optimum range

129
Q

Where are ampullae of lorenzi found and what is their function

A

Found on the sharks and rays, these sensory structures detect the electric fields associated with muscle activity in potential prey species. They also detect temperature.

130
Q

Electroreceptors in other animals

A

present in the monotremes e.g. duck billed platypus (aquatic) and echidna (terrestrial – spiny anteater) which have ampullae like receptors on the beak/snout.

131
Q

Ampullae of lorenzi - where are the sensory nerve endings

A

Sensory nerve endings lie at the base of a pit filled with a conductive gel. Prey can be detected even when not visible (murky water or under sand/sediment

132
Q

What are electrical fields used for in fish

A

detection of prey, navigation and communication

133
Q

What detects the electrical fields

A

modified muscle cells (which are stacked up like batteries)

134
Q

Why is the signal amplitude kept low in fish

A

because producing the electric discharge is energetically expensive and can be detected by some predators.

135
Q

How long do elongated muscle cells work for communication in fish

A

work like battery – different types which stun prey (just a big pulse). Communication, series of pulses for navigation. By the wall, higher frequency

136
Q

Why do birds use magnetic fields

A

for dircetion during migration but how this is achieved remains highly controversial

137
Q

How can birds detect a magnetic field - magnetic metals

A

magnetic metal crystals (magnetite – similar to a compass needle) if these were present in nerve cells. - Magnetite granules are present around the beak in some birds but in macrophages, not neurons.

138
Q

How can birds detect a magnetic field - electrorecptors

A

might be activated by moving through a magnetic field….. but birds don’t appear to have such receptors

139
Q

How can birds detect a magnetic field - magentics and vision

A

Magnetic sense seems to be linked to vision - It is only present when birds are under full spectrum white light. The current favoured theory is that the magnetic field alters the spin state of high energy electrons generated when photopigments absorb light energy.

Structure And Function Of Living Organisms (10 decks)

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