Vision Lecture Flashcards
What is scotopic vision?
the function of the eye in very low light
What is mesopic vision?
at the threshold of cone vision in low light
what is photopic vision?
eye functioning under well lit conditions, color vision
what is the function of the 3rd eyelid?
keeps the eye moist, removes irritants from the eye, and shields the eye
objects in the retina are inverted onto the rentina. true or false?
true! our brain turns this backwards image right side up again
light rays are bent/refrracted the most at the _____
cornea
what is accommodation?
viewing distant objects requires ______ accommodation
viewing close objects require requires _____ accommodation
the process of refracting light rays to focus them on the retina
no
yes
the parasympatheitc system ____ pupils and _____ accommodation.
the sympathetic nervous system ____ pupils and ____the lens
contricts
promotes
dilates
flattens
what are the layers of the retina in order from back of the eye to front of the eye?
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
what is the tapetum lucidum for?
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
light causes a confirmational change in ______. This leads to _____ of the rod cell by closure of _____
retinal vitamin A derivative
hyperpolarization
sodium channels
dogs have a ____ system. Horses have ____
2 cone (green/yellow and blue)
red and blue cones but no green
what is the dazzle relfex?
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
what is the pupillary reflex?
reduction in pupil size hen there is a bright light. it should happen in both eyes.
what is the menace response?
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.