Sight (Vision) Flashcards
Conjunctiva
The first layer of the eye that light hits
Cornea
Transparent thick sheet of tissue in the eye
Anterior chamber
Space filled with aqueous humor that puts pressure to maintain the shape of the eyeball
Pupil
The hole of the eye determined by the iris; determines eye color
Lens
Bends the light so that it goes to the back of the eyeball
Cilia Body
Secretes aqueous humor; consists of supersensory ligaments and ciliary muscle
Posterior Chamber
Space behind the ciliary muscle that is filled with aqueous humor
Vitreous Chamber
Filled with vitreous humor; provides pressure to the eyeball
Retina
The back of the eyeball; filled with photoreceptors
Photoreceptors
Specialized nerve cells located on the retina and capture light and convert it to neural impulses
Macula
A special part of the retina that is filled with cones
Fovea
A special part of the retina that is filled with rods; no cones. It is the center of the eyeball’s visual field.
Choroid
The pigmented vascular layer of blood vessels in the eye between the retina and the sclera
Sclera
The white of the eye that covers about 5/6th of the posterior eyeball. It is the attachment point for muscles
Rods
Photoreceptors for night vision; capturing light turns it off and turns on a bipolar cell => turning on a retinal ganglion cell => optic nerve
Cones
Photoreceptors for color vision; almost all of them are centered in the fovea. There are three types: red, green, and blue
Phototransduction Cascade
The process that turns rods and cones off
(Light hits retinal, which changes shape and changes the shape of rhodospin/photopsin. This frees transducin which binds to phosphodiesterase which changes cGMP to GMP, activating sodium channels). This turns on bipolar cells
Differences between rods and cones
- 120M rods vs 6 million cones
- Rods concentrated in fovea vs cones in the preiphery
- Rods are 1000X more sensitive to light vs rods detect color
- Rods have slow recovery time; cones are fast
Blind Spot
Where the optic nerve connects to the retina – no rods or cones
Visual Field Processing in the Brain
The right eye goes to the left side of the brain and vice versa
Parallel Processing
Simultaneous Processing of incoming stimuli that differ in quality – color, motion, size, etc.
Trichromatic Theory of Color Vision
We have three types of cones: red, green, and blue. Mixing them gives us the different colors we see
Opponent Process Theory of Color Vision
There are two pairs of two opposing colors: red/green and blue/yellow. In a given cone, only one can dominate at a time
Photopic vision
Vision under well-lit conditions
