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Physiology 201 > Unit 5 Lecture 38 > Flashcards

Unit 5 Lecture 38 Flashcards

1
Q

What is the sensory surface of the eye?

A

retina

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2
Q

What is the bending of light rays?

A

Refraction

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3
Q

When does refraction occur?

A

Occurs when light passes from one medium (air) into another (water)

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4
Q

Where does most refraction take place?

A

Cornea

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5
Q

What is the purpose of the lens?

A

critical ‘fine tuning’ of refraction

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6
Q

What happens when bright light goes into the eye?

A

The pupil gets SMALLER bc CIRCULAR muscles of iris contract

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7
Q

What nervous systems control the constriction and dilation of the eye?

A

constriction= Parasympathetic NS

dilation = sympathetic NS

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8
Q

What happens when normal light goes into the eye?

A

Iris muscles relax and the pupil is normal

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9
Q

What happens when dim light goes into the eye?

A

The pupil get BIGGER (dilates) bc RADIAL muscles of the iris contract

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10
Q

What is the function of the iris

A

regulates light entry

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11
Q

How does the eye see images from long distances?

A

In parallel rays

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12
Q

How does the eye see images close up?

A

In non-parallel rays

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13
Q

What happens to light when it enters a new medium?

A

bends (refracts)

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14
Q

Where does the eye make an image when the object is far away?

A

Plane of the retina

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15
Q

Where does the eye make an image when the object is up close?

A

Behind the retina

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16
Q

What objects look out of focus?

A

Close up things

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17
Q

How does the eye focus things up close?

A

Accomodation

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18
Q

Define accomodation

A

The change of lens shape to see things up close

19
Q

Steps of accomodation

A
  1. Lens gets round
  2. Entering angle of light increases
  3. Light gets more bent so the image falls on retina
20
Q

How does the lens become more round?

A

Suspensory ligaments loosen up -> less tension on lens

21
Q

Define presbyopia

A

Can’t see things up close because the lens tightens with old age and can’t get round

22
Q

Define emmetropia

A

Eyes without vision problems

23
Q

Define hyperopia

A

short eyeball

24
Q

What happens with hyperopia?

A

Image falls behind retina

25
Q

Define myopia

A

Long eyeball

26
Q

What happens with myopia?

A

Image falls in front of retina

27
Q

The retina is made of many what?

A

layers

28
Q

What are the layers of the retina?

A
  • Ganglion cell layer
  • Neuron layers
  • Photoreceptor later
29
Q

Function of the ganglion cell layer

A

carries signals to the brain

30
Q

Function of the neuron layers?

A

Processes photoreceptor signals

31
Q

What are the 2 cell types in the photoreceptor layer?

A

Rods and cones

32
Q

What is a rod?

A

Processes black and white, VERY sensitive, dim light

33
Q

What is a cone?

A

Color vision, not as sensitive, bright light

34
Q

What is the path of light through the retina?

A

Ganglion Cell L -> Neuron L -> Photoreceptor L

35
Q

What is the path of visual data processing?

A

Photoreceptor L -> Neuron L -> Ganglion Cell L

36
Q

Characteristics of rods

A
  • sensitive to light
  • Black and white
  • @ periphery of retina (whole back of eye but the macula)
  • LARGE receptor field
  • senses movement
37
Q

Characteristics of cones

A
  • Not sensitive
  • COLOR
  • @ macula lutea (circle on retina)
  • SMALL receptor field
  • differentiates wavelength
38
Q

What is the light receptor in rods called?

A

Rhodopsin

39
Q

What is Rhodopsin made of?

A

opsin and retinal

40
Q

Explain rod phototransduction

A
  1. Light photon absorbed in retinal
  2. Opsin is activated -> breaks down”chemical messenger” cyclic GMP (cGMP) that keeps Na+ channels open
  3. cGMP-gated sodium channels close
  4. Rod hyperpolarizes
  5. Glutamate is NOT released
41
Q

What is glutamate?

A

a popular neurotransmitter in the brain

42
Q

What are the two “halves” of the eye?

A

Nasal and temporal

43
Q

What half of the eye has the larger receptor density

A

Temporal…. that’s the side with the blind spot

Physiology 201 (38 decks)

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