Lecture 20 - senses II

Question 1

can most invertebrates hear?

Answer 1

no

Question 2

What do some insects use to detect sound?

Answer 2

Tympanic organs

Question 3

how does a Moth’s detection of bat ultrasound work?

Answer 3

A1 & A2 receptors: different sensitivity
A2 signals ‘too loud’
(bat too close -> moth drops)

Question 4

What are the key structures in Vertebrate hearing?

Answer 4

Pinna
Tympanic membrane
Middle ear bones
- Malleus
- Incus
- Stapes
Inner ear
Oval window
Cochlea
- Tectorial membrane
- Hair cells

Question 5

how does the inner ear detect sounds?

Answer 5

Fluid moves hair cells of Organ of Corti (in cochlea), causing the Basilar membrane & hair cells to
oscillate.

Question 6

The location of Resonance of basilar membrane allows the ear to determine?

Answer 6

frequency

Question 7

what are the different Hair cells of Organ of Corti?

Answer 7

Outer hair cells: attached to tectorial, mainly amplify

Inner hair cells: free in fluid, mainly detect

Question 8

What frequency range can most mammals hear in?

Answer 8

<20 kHz

Question 9

How do owls detect vertical angles?

Answer 9

Asymmetrical “ear flaps” and placement of ear canals

Question 10

How do males and females differ in hearing loss?

Answer 10

females lose lower freq,

males lose higher freq

Question 11

What are Bats hearing adaptations for echolocation?

Answer 11

high pitch for high temporal
resolution
modified larynx

Question 12

What is Photoreception

Answer 12

sight/light detection

Question 13

What makes soft-furred tree mice unique?

Answer 13

convergent evolution: tree mice use Ultrasonic sounds to navigate environment

Question 14

How does Photoreception work?

Answer 14

There are Light-sensitive pigments (rhodopsins = retinal + opsin). Light causes photochemical reaction with retinal (carotenoid derivative of vitamin A)

Question 15

What is the signal pathway of Photoreception?

Answer 15

Isomerisation of retinal -> opsin protein ->

excitatory cascade -> nerve signal

Question 16

What are lights key traits?

Answer 16

Direction
Colour (wavelengths)
Polarity

Question 17

What is the structure of compound eyes?

Answer 17

Many sensilla with lens and receptor cells

ommatidia

Question 18

Apposition eyes

Answer 18

each ommatidium (with lens and photoreceptor) acts
independently.
Good for bright conditions

Question 19

Superposition eyes

Answer 19

transparent zone below lens where light from several
ommatidia reach same photoreceptor.
Good for dark conditions
Prevent damage in bright conditions using pigment to block side of ommatidium

Question 20

Neural superposition

Answer 20

Apposition eye with lenses and nerves that results in

seven times stronger signal

Question 21

What causes the blindspot in vertebrate eyes?

Answer 21

Optic nerve passes through retina

Question 22

How do Vertebrate eyes work?

Answer 22

light is refracted by the cornea and lens. Light then passes through neurons and photoreceptors.

Question 23

What are the two types of photoreceptor cells?

Answer 23

Rods and cones

Question 24

what is the Fovea?

Answer 24

The area with the highest density of cones

Question 25

What are the rods in the eye for?

Answer 25

Low light levels

Question 26

What are the cones in the eye for?

Answer 26

Bright light, high resolution

Question 27

What is the tapetum lucidum?

Answer 27

The structure that reflects the light back into the receptors allows for increased vision in low light.

Question 28

What is Binocular vision an adaptation for?

Answer 28

hunting

climbing

Question 29

What advantage does having Binocular vision?

Answer 29

Gives an increased perception of depth?

Question 30

How does Binocular vision work?

Answer 30

Visual cortex compares two images