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BIO2242 > Practical 8 > Flashcards

Practical 8 Flashcards

1
Q

Light blocking pigments in the ommatidia of Drosophila are red. This suggests that?

A

They cannot see the colour red and it is instead reflected. They can see colours like blue and green, however.

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2
Q

What is the function of the tapetum lucidum?

A

It reflects light back towards the retina, allowing secondary absorption of very low-intensity light for photoreceptors. This enhances photosensitivity under low light, enabling above average night vision.

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3
Q

Which of the following is a distinction between gustation and olfaction in vertebrates?

A
  • Olfaction is used for the sense of smell.
  • Gustation is used for the sense of taste
  • Olfaction receptors occur at the top back of the nasal vault
  • Gustation receptors occur on the upper surface of the tongue
  • Gustation occur on the surface
    Olfaction occurs beneath several cell layers
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4
Q

The mosquito shown here is likely to be? (what sex)

A

If the antennae are hairy it is a male.

If the antennae are not hairy it is a female.

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5
Q

Trichoid sensilla

A

Hairs set in flexible sockets connected to a short dendrite

Pressure or vibration will move the hair causing the movement to be registered by the dendrite.

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6
Q

Campaniform sensilla

A

Used for measuring stress by the deformation of a dome.

When the cap experiences pressure, it deforms, and the dendrite beneath it transmits a sensory signal.

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7
Q

Are trichoid sensilla purely mechanosensory structures or do they also serve other purposes?

A

Trichoid sensilla can also act as olfactory sensors and gravity receptors.

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8
Q

What are the 4 main groups of sensilla on an insect’s body?

A

Olfactory
Gustatory
Mechanosensory
Thermo-hygroreceptors

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9
Q

Do the sensilla on an insect’s body display slow or rapid adaptation to mechanosensory stimuli?

A

They show rapid adaptation to sensory stimuli.

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10
Q

What is the significance of the elliptical shape of the dome on campaniform sensilla?

A

The elliptical shape helps it extend on either side and provides directional sensitivity

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11
Q

Are there other forms of mechanoreceptors in insects?

A

Yes

  • hair plates
  • Chordotonal Organs
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12
Q

What are the different touch receptors in mammalian skin?

A 
Free Nerve endings
Mesiner's corpuscles 
Merkel cell
Pacinian corpuscle 
Ruffini ending
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13
Q

What is meant by slow adapting and rapid adapting receptors?

A

Slow adapting: Continue responding for as long as stimulus is present
Rapid-adapting: Single response when stimulus is first applied.

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14
Q

What is a free Nerve ending and is it rapid of slow adapting?

A

Free nerve endings are sensitive to painful stimuli, temperature and to light touch.
They are either rapid or slow

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15
Q

What is a Mesiner’s corpuscles and is it rapid of slow adapting?

A

Senses fine, discriminative touch and low-frequency vibration.
It is rapid adapting

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16
Q

What is a Merkel cell and is it rapid of slow adapting?

A

Senses gentle touch.

Slow adapting

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17
Q

What is a Pacinian corpuscle and is it rapid of slow adapting?

A

Sensory nerve for pressure and vibration.

Rapid adapting

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18
Q

What is a Ruffini ending and is it rapid of slow adapting?

A

Record low-frequency vibration or pressure.

Slow adapting

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19
Q

What are receptive fields?

A

Receptive fields are regions in which stimuli can influence electrical activity in sensory receptors

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20
Q

How do the receptive fields differ in size between each of these receptors?

A

Receptive fields of each of the receptors depends on the depth of the receptor within the skin.
The merkels disk and Meissners corpuscles are located at the surface of the skin so therefore have smaller receptive fields.
The Ruffini endings and Pacinian corpuscles are located deeper in the skin layers os therefore have larger receptive fields.

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21
Q

What is two-point discrimination?

A

Two-point discrimination is the ability to discern the two nearby objects touching the skin are truly distinct points, not one.

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22
Q

Which receptor type would be employed for two-point discrimination

A

The main receptor type employed for 2 point discrimination is Meissner’s corpuscles.

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23
Q

On which part of the body would we display greater two-point discrimination, the back of the hand, fingertips or back of the neck?

A

Fingertips = highest level of two-point discrimination
Back of hand = next highest of the three skin regions
Back of neck = Lowest level of two-point discrimination

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24
Q

How does two-point discrimination relate to the size of the receptive fields for each of these body parts and the area of brain devoted to receiving input from the parts?

A

The smaller the receptive field size, the larger proportion of the brain dedicated to the body part.
Fingertips have the smallest receptive field size and one of the largest areas of the somatosensory cortex.

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25
Q

How do tympanal organs work in insects?

A

Very sensitive setae or tympanal organs may detect specific frequencies of airborne sounds.
In the tympanal organs several sensory cells extend to a very thing tympanic membrane that encloses an air space in which vibrations are detected.

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26
Q

What is Johnston’s organ?

A

It is a collection of sensory cells arranged in a bowl shape. It detect motion of the flagellum and turns them into nerve impulses.

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27
Q

How does Johnston’s organ work?

A

The sensory cells within the Johnston’s organ stretch upon vibration. Mainly used to detect courtship sounds through the beating of male’s wings.

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28
Q

Why do only male mosquitoes have hair antennae?

A

Enables the males to hear the flight sounds caused by females.
By displacing the bristles and antennae shaft, this increases sensitivity of the harmonic oscillations, transmitting the signal to the sensitive Johnstone Organ.

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29
Q

What is the role of the small “feather-like” extension that branch from the flagellum in Drosophila antennae?

A

In drosophila, both sexes possess the arista which allows antennae to vibrate in response to the frequency of the drosophila. (Allows for mating calls)

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30
Q

What does the outer ear consist of?

A

earlobes and the auditory canal leading to the tympanic membrane (eardrum)

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31
Q

What does the middle ear contain?

A

It is an air-filled cavity inside the skull.

Contains the three ear bones (ossicles) that transfer the vibrations of the tympanum to the inner ears

32
Q

What is the inner ear?

A

It is a series of fluid-filled cavities and canals also called the labyrinth

33
Q

What is the purpose of the hair cells within the canals and chamber of the inner ear?

A

In the canals, they register the movement of the fluid.
In the chambers, they are tied to small weights to register the position of the head relative to the direction of gravity.

34
Q

What is the semicircular canals in the vestibular system?

A

The semicircular canals are 2 small, fluid-filled tubes in our inner ear.

35
Q

What is the function of the semicircular canals?

A

They help us keep our balance and sense of direction, and the speed of angular or rotational acceleration.

36
Q

What are the otolith organs in the vestibular system.

A

They are made up of the saccule and utricle of the vestibule of the inner ear.

37
Q

What is the function of the otoliths?

A

They sense the direction and speed of linear acceleration with regard to the position of our head to gravity.

38
Q

Why have three semi-circular canals evolved in gnathostomes?

A

They are positioned at right angles to one another and so are able to detect movements in three-dimensional space.
They function as detectors for angular acceleration in their respective planes

39
Q

How is sound transmitted to the cochlea?

A

First, sound waves hit the ear lobe (Pinna).
Then these sound waves travel down the auditory canal towards the tympanic membrane (eardrum).
These sound waves put pressure on the tympanic membrane causing it to press against the 3 smallest bones in the body, the malleus, incus, and stapes.
The stapes then vibrates causing the fluid in the cochlea to move

40
Q

What is the function of the Pinna?

A

Collects sound waves and helps move them into the ear canal

41
Q

What is the function of the Auditory canal?

A

A long tube that extends through the temporal bone and ends at the ear drum

42
Q

What is the function of the Tympanum?

A

Also called the eardrum. Separates the outer ear from the middle ear.
When vibrations reach the membrane they are then transferred to the tiny bones in the middle ear.

43
Q

What is the function of the Cochlea?

A

A spiral, hollow bone in the inner ear.

Here microscopic hair cells are stimulated based on frequency and pitch and are converted to electrical impulses.

44
Q

What is the function of the Malleus?

A

Also known as the hammer, located in the inner ear.

It transmits the sound vibrations to the Incus.

45
Q

What is the function of the Incus?

A

is the middle of the 3 small bones.

It transmits the vibrations it received from the malleus to the stapes.

46
Q

What is the function of the Stapes?

A

is the smallest of the 3 middle bones

The base of the bone articulates with the oval window and transmits the vibrations to the cochlea.

47
Q

What is the function of the Eustachian Tube?

A

Small passageway connecting the throat and middle ear.

Stops pressure and fluid building up inside the ear.

48
Q

What is the function of the Scala tympani?

A

Helps transduce the movement of air that causes vibrations in the tympanic membrane.

49
Q

What is the function of the Scala media?

A

Contain the Organ of Corti - the receptor organ for hearing

50
Q

What is the function of the Scala vestibule?

A

Conducts sound vibrations into the cochlear duct

51
Q

What is the function of the Tectorial membrane?

A

Covers the sensitive micro hairs of the sensory receptor cells in the inner ear

52
Q

What is the function of the Basilar membrane?

A

A stiff structure within the cochlea that separates the two fluid-filled tubes - scala media and scala tympan

53
Q

How does the width and thickness of the basilar membrane change from the base to the apex of the cochlea and how do these changes affect the stiffness of the membrane?

A

The membrane decreases in thickness from the base to the apex of the cochlear.
Having a thick stiff stable basilar membrane allows us to detect extremely high frequencies

54
Q

Which region of the cochlea contains hair cells that will respond to high-frequency sounds, and which regions will respond to low-frequency sounds?

A

Higher pitched frequencies are registered closest towards the Basilar membrane.
Lower pitched frequencies are registered further from the membrane.

55
Q

How do vertebrates localize sound?

A

Locate sound based on which ear the sound appears loudest, or the timing of the sound.
Humans do this by the binaural comparison of intensity, phase and time of arrival.

56
Q

Is the difference in the loudness of the timing of the sound reaching each ear used to determine the point of origin?

A

Yes

57
Q

Sclera

A

The whit outer layer of the eye

58
Q

Rods

A

Photoreceptor cells that work well in low-light conditions, differentiates between light intensities

59
Q

Cones

A

Photoreceptor cells that work well in well-lit conditions enables tetrapods to see colours

60
Q

Ganglion cell layer

A

Contains the start of the retinal ganglion cells which eventually transmit visual signals to the brain

61
Q

Inner plexiform layer

A

Contains synaptic connections between the axons of bipolar cells and dendrites of ganglion cells

62
Q

Inner nuclear layer (bipolar cells)

A

Contains three neural cell types which transmit the visual signals fro the photoreceptors to the ganglion cells

63
Q

Outer plexiform layer

A

Network of synapses between dendrites of horizontal cells from the inner nuclear layer, and photoreceptor cell inner segments from the outer nuclear layer

64
Q

Outer nuclear layer (photoreceptor cells)

A

Contains rods and cones

65
Q

Optic nerve fibres

A

Transmit the visual signals to the brain

66
Q

Pigment

A

The layer just above the choroid that gives the eye colour

67
Q

Choroid

A

A layer of tissue within the wall of the eye which supplies nutrients and maintains volume and temperature

68
Q

Does every neuron in the optic nerve carry information from a single or multiple photoreceptors?

A

Each neuron in the optic nerve carries information from multiple photoreceptors

69
Q

What is the function of the pigment layer right behind the photoreceptors in the eye?

A

Functions as both a selective barrier and a metabolic regulator of the overlying photoreceptor layers.

  • Transport of nutrients, ions, and water
  • Absorption of light and protection against damage
  • Secretion of various essential factors for the structural integrity of the retina
70
Q

What is the purpose of the reflective tapetum lucidum found in many vertebrates?

A

The tapetum lucidum is the reflective layer that sits between the retina and the lens.
The tapetum lucidum enhances photosensitivity under low light, enabling above-average night vision.
It reflects light back towards the retina, allowing secondary absorption of very low-intensity light for photoreceptors.

71
Q

Why do the eyes of herbivores appear to bulge more than carnivores?

A

Positioning the eyes on the side of the head results in less overlap but a wider range of vision.
Useful for prey in detecting the presence of a predator.

72
Q

Do arthropods have any other forms of eyes or photoreceptors beyond compound eyes?

A

Some classes (Class Archnida, order Araneae) have simple eyes

73
Q

How do compound eyes work?

A

Light stimulus passes through each lens and is captured by visual pigments in the rhabdomoeres.
Pigment between each ommatidia separates the light stimuli from each individual ommatidia so that they are getting multiple images that the brain morphs into one.

74
Q

Do animals with compound eyes see a large number of duplicate images?

A

They do not see a large number of duplicate images but rather one clear consistent image

75
Q

The light-blocking pigments in the ommatidia of Drosophila are red. What colour of light will these pigments absorb? What is their function? What does this suggest about the colour vision of Drosophila?

A

These pigments will absorb light at higher frequencies (green and blue light).
They are heavily pigmented and stop light entering the ommatidium through sides via neighboring ommatidium.
They cannot see red.

76
Q

In which part of the spectrum would you expect their (Drosophilla’s) colour vision to be sensitive to?

A

Spectrum would be sensitive to short wavelengths which contain the colours violet, blue and green

77
Q

Mutant strains of Drosophila exist in which the light-blocking pigments in the ommatidia are absent. What consequence will this have for the amount of light reaching the photoreceptors and the precision of the image formed in these Drosophila?

A
  • The secondary compound eye structure is absent so the light goes right through
  • Because of this, Drosophila lose any sense of directionality of the compound eye
  • Results in blindness

BIO2242 (33 decks)

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