Vision Lecture

Question 1

What is scotopic vision?

Answer 1

the function of the eye in very low light

Question 2

What is mesopic vision?

Answer 2

at the threshold of cone vision in low light

Question 3

what is photopic vision?

Answer 3

eye functioning under well lit conditions, color vision

Question 4

what is the function of the 3rd eyelid?

Answer 4

keeps the eye moist, removes irritants from the eye, and shields the eye

Question 5

objects in the retina are inverted onto the rentina. true or false?

Answer 5

true! our brain turns this backwards image right side up again

Question 6

light rays are bent/refrracted the most at the _____

Answer 6

cornea

Question 7

what is accommodation?

viewing distant objects requires ______ accommodation

viewing close objects require requires _____ accommodation

Answer 7

the process of refracting light rays to focus them on the retina

no

yes

Question 8

the parasympatheitc system ____ pupils and _____ accommodation.

the sympathetic nervous system ____ pupils and ____the lens

Answer 8

contricts

promotes

dilates

flattens

Question 9

what are the layers of the retina in order from back of the eye to front of the eye?

Answer 9

pigmented epithelium: nurtures the rods and cones, recycles photoreceptor discs

Photosensitive layer: where the rods and cones are

External limiting membrane: determines the boundaries of radial astrocytes that support retinal neurons

External nuclear layer: contains the nuceli of photoreceptors

External plexiform layer: synapses between photoreceptors and bipolar nuerons

Inner nuclear layer: nuclei of bipolar cells

Internal pleiform layer: synpase between bipolar neurons and ganglion nuerons

Ganglion layer: cell bodies and nuceli of ganglion

nerve fiber layer: axons from ganglion neurons

Question 10

what is the tapetum lucidum for?

Answer 10

it is a reflective layer of cells behind the retina and it reflects the light back into the photoreceptors which boosts the ability to see in low light. HOWEVER it does reduce acuity

Question 11

light causes a confirmational change in ______. This leads to _____ of the rod cell by closure of _____

Answer 11

retinal vitamin A derivative

hyperpolarization

sodium channels

Question 12

dogs have a ____ system. Horses have ____

Answer 12

2 cone (green/yellow and blue)

red and blue cones but no green

Question 13

what is the dazzle relfex?

Answer 13

when you shine a bright light into the eye and the eyelids should close. requires a functioning retina, optic nerve, optictract and midbrain, but does not require occipital cortex

Question 14

what is the pupillary reflex?

Answer 14

reduction in pupil size hen there is a bright light. it should happen in both eyes.

Question 15

what is the menace response?

Answer 15

cover one eye and with the other eye uncovered, move the hand towards the eye. this will elicit a learned menace response. it tests the integrity of cranial nerve pathways. requires cortical circuits to be present and cerebellar circuits. requires retina, visual pathways, visual cortex, and cranialnerve 2 to be in tact.

Question 16

central processing occurs in what 3 locations?

Answer 16

the lateral geniculate visual cortex pathway

retinotectal pathway controlling pupillary reflexes

retinohypothalamic pathway important for circadian rhythms

Question 17

binocular vision offers what two things? which animals tend to have greater binocular vision?

Answer 17

stereopsis (depth perception)

binocular summation

predators since their eyes are more forward facing

Question 18

simple cells in the visual cortex respond to _____

complex cells respond to _____

Answer 18

lines placed in certain areas of the visual fields in certain oreintations

edges or lines in a particular orientation no matter where they are in the visual field

Question 19

where are the two streams from the visual cortex?

Answer 19

the dorsal stream: occipital lobe, pareital lobe, spatial location, the “where)

the ventral stream: occipital lobe, temporal lobe, visual identification, the “what”