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Physiology Exam 4 > Neurophysiology 7: Vision (Lecture 81) > Flashcards

Neurophysiology 7: Vision (Lecture 81) Flashcards

1
Q

Eyes that are binocular are indicative of?

A

Carnivores or predators

Have better depth perception

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2
Q

Eyes that are lateralized are indicative of?

A

Ruminants or prey

Have larger fields of vision

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3
Q

What are the three tunics/layers of the eye?

A

Fibrous
Vascular
Nervous System

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4
Q

Where are the photo receptors located?

A

On the back of the retina

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5
Q

Where is the visual blind spot?

A

Optic disk

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6
Q

Which part of the eye does the majority of the bending of the light?

A

Cornea

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7
Q

Does the cornea or lens refract more light?

A

Cornea refracts light more than the lens does

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8
Q

Light is _______ _____ and ____ on the retina

A

Upside down
Reversed

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9
Q

What are the layers of the retina?

A
  1. Pigament cell layer
  2. Photoreceptor layer
  3. Outer nuclear layer
  4. Outer plexiform layer
  5. Inner nuclear layer
  6. Inner plexiform plexus
  7. Ganglion cell layer
  8. Optic Nerve Layer
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10
Q

What is the function of the pigament cell layer ?

A

Absorbs light and prevents light scatter between photoreceptors

Convert trans-retinal to cis-retinal needed by photoreceptors

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11
Q

What is the Tapetem lucidum?

A

Reflective layer in choroid that increases light detection in dark conditions

Retinal pigment epithelium lacks melanin overlying tapetum

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12
Q

What are the two photoreceptors?

A

Rods and cone

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13
Q

What is the photoreceptors type of the rod? What is the function of this?

A

Rhodopsin

Absorbs light

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14
Q

What part of vision do rods aid in?

A

Night
Scotopic vision
Monochromatic vision

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15
Q

What part of vision do cones aid in?

A

Color, photopic, or day vision

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16
Q

What is the photoreceptors type of the cones?

A

Photopsins or iodopsins

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17
Q

How many photopsins do humans and primates have? How many do dogs have?

A

3 types in humans and primates
2 types in dogs, horses, and other domestic animals

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18
Q

How to stimulate action potential in rods and cones?

A

G-protein coupled receptors

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19
Q

In the dark, rhodopsin contains _________

Light absorption causes transformation to ________, which dissociates from opsin (bleaching reaction)

A

Cis-retinal

Trans-retinal

20
Q

After bleaching, rhodopsin must be rebuilt for the rod to function. What is this process?

A
  1. Trans-retinal transported to pigmented layer and actively converted to cis-retinal
  2. Cis-retinal transported back into rod and combined with opsin
  3. Process is slow for rhodopsin—rods don’t function well in bright light
21
Q

After bleaching, the process for cone photospins is similar to that of rhodopsins. BUT how does it differ?

A

THIS IS FASTER THAN THE PROCESS FOR RHODOPSIN

1.) more intense light needed for bleaching
2.) photopsin regenerates rapidly

22
Q

Explain the phototransduction process.

A
  1. Conversion of cis->trans-retinal changes shape of G-protein
  2. PDE degrades cGMP
  3. CGMP gated Na+ channels
  4. Hyperpolarize the cell and decrease glutamate release
23
Q

What is the first order neuron for the retinal pathway?

A

Bipolar cell

24
Q

What is the 2nd order neuron for the retinal pathway?

A

Ganglion cells

25
Q

Under what condition do rods work best? Why is this?

A

Rods work best in dim light/dark conditions

One photon of light can activate a rod, many needed to activate a cone

26
Q

Why can one photon of light activate a rod, but you need many to activate a cone?

A

Due to greater sensitivity and amount of photo pigment in rods

27
Q

Why are bipolar cells more likely to be activated by low levels of light?

A

Convergence of rods

28
Q

Why is there less sensitivity of cone pathway to light?

A

One cone or just a few cones converge on one bipolar cell

29
Q

What makes up a bipolar cell? (For rods)

A

Many rods converge

30
Q

What is the pathway for conscious perception of vision?

A

Optic nerve -> optic chasm -> optic tract ->

31
Q

Where is the lateral geniculate nucleus?

A

In the thalamus

32
Q

What is the 3rd oder neuron in the conscious perception of vision pathway?

A

Lateral geniculate nucleus in thalamus

33
Q

Each visual field represented in the ______ optic tract.

A

Contralateral

34
Q

The closer together the eyes are, the more _____________________________,

A

The more input each eye gets from BOTH visual fields

35
Q

Increased medial eye placement -> _____ _____ _______ ______ -> _______ _______ ________ _______

A

Increased binocular vision overlap -> decreased decussation at optic chiasm

36
Q

(True/false) Visual input that crosses the midline before entering the eye does NOT need to cross the midline again.

A

True

37
Q

Which species has more decussation: cat or horse?

A

A horse

38
Q

Does a pupillary light response mean that the animal is visual in that eye?

A

No

39
Q

(TRUE/FASLE) Having a pupillary light response does not guarantee that we have conscious perception of vision.

A

TRUE

40
Q

What two fibers does the optic tract contain?

A

Pupillary light response
Vision fibers

41
Q

Where is the pupillary light response located?

A

Is subcortical

Midbrain

42
Q

What does anisocoria mean?

A

Different size pupils

43
Q

More decussation = more ____ the eyes

A

Lateral

44
Q

What type of response is the menace response?

A

Cortical response

45
Q

Describe the menace reflex pathway

A

Menace reflex tests the retina -> optic nerve -> optic chiasm -> optic tract -> visual cortex -> facial nucleus in medulla

46
Q

What is the vestibulo-ocular reflex?

A

Initiates compensating eye movement to keep vision fixed when head turns

CHICKEN VIDEO SLAY SLAYYYYY

47
Q

Visual startle reflex pathway?

A

Rostral colliculus in midbrain -> decussation -> descends cord in the to spinal tract -> contraction of neck muscle to turn toward stimulus

Physiology Exam 4 (8 decks)

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