Chapter 2 – Light And The Eyes Flashcards
Electromagnetic radiation
If physical phenomenon that is simultaneously both away the end of stream of particles
Electromagnetic spectrum
The entire range of wavelengths of electromagnetic radiation
Photons
Single particles of light a photon is the smallest possible quantity of electromagnetic radiation
Optic Array
The spatial pattern of light rays, varying in brightness and color, entering your eyes from different locations in a scene
Extraocular muscles
Three pairs of muscles around each I thought enable us to move our eyes very rapidly and accurately and keep the eyes always pointed in the same direction
Optic axis
And imaginary diameter line from the front to the back of the eye, passing through the centre of the lens
Sclera
The outer membrane of the eye, a tough protective covering who is visible portion is the weight of the eye and the transparent cornea at the front of the eye
Choroid
The middle membrane of the eye, lining the interior of the sclera and containing most of the blood vessels that supply the inside of the eye with oxygen and nutrients
Retina
The inner membrane of the eye, made up of neurons, including the photo receptors that convert the light entering the eye into neural signals
Cornea
Transparent membrane at the front of the eye; light enters the eye by first passing through the cornea, which sharply refracts the light
Iris
Coloured part of the eye – a small circular muscle with an opening in the middle (people) through which light enters the eye
Pupil
An opening in the middle of the iris, through which light enters the eye
Anterior chamber
The space between the cornea and the iris, filled with aqueous humour
Pupillary reflex
The automatic process by which the iris contracts and relaxes to control the size of the people, in response to the relative brightness of light entering the eye
The posterior chamber
The space between the iris in the lens, filled with aqueous humour
Aqueous humour
But clear, thin fluid filling the anterior and posterior chambers of the eye
Vitreous humour
A clear, somewhat gel like fluid filling the vitreous chamber of the eye
Lens
Transparent structure near the front of the eye that refracts the light passing through the pupil so that the light focus properly on the retina
Ciliary Muscles
Tiny muscles attached to the choroid; they were locks and contract to control how the choroid polls on the zonule fibres to change the shape of the lens
zonule: fibres that connect the lens to the choroid, they pull on the lens to change its shape
Photo receptors
Retinal neurons (rods and cones) that transduce light into neural signals
Nuclear layers
The three main layers of the retina including the outer nuclear layer, and a nuclear layer, and the ganglion cell layer
Outer: The layer of the retina consisting of photo receptors
Inner: The layer of the retina that contains bipolar cells, horizontal cells, and amacrine cells
Synaptic layers
In the retina, till they are separating the three nuclear layers – the other synaptic layer and the intercept optic layer
Rods/cones
One of the two classes of photo receptors, named for their distinctive shape
Ganglion cell layer
The layer of the retina that contains retinal ganglion cells
Optic desk (or Blindspot)
Location on the written over the axons of RGC exit the eye contains not a photo receptor
Optic nerve
Nerf formed by the bundling together of the axons of our RGC, it exits the eye through the optic disc
Fovea
A region in the centre of the retina where the light from objects at the centre of our gaze strikes the retina, contains no rods and a very high density of cones
Luminance contrast
A difference in the intensity of illumination at adjacent retinal locations
Photo pigment
A molecule with the ability to absorb light and initiate transduction
Spectral sensitivity
The degree to which a photo pigment molecule absorbs light of different wavelengths
Photoisomerization
A change in shape by a photo pigment molecule from one isomer to another. When the molecule absorbs the photon, initiates the transduction of light to a neural signals
Operating range
The visual system sensitivity to the range of light intensity is within the current Scene; the visual system adjust to operating range according to current conditions
Dark adaptation
The process of adjusting retinal sensitivity, changing the operating range, as the person moves from a bright environment to a darker one, the reverse process is called light adaptation
Convergence
A property of retinal circuits in which multiple photo receptors send signals to one retinal ganglion cell
Spatial summation
A property of retinal circuits with convergence in which signals from photo receptors in some small space at the rental Samantha to affect the response of the retinal ganglion cells in the circuit
Receptive field
The region of the sensory surface that when stimulated causes a change in the firing rate of a neuron that “monitors” the region of the surface, the receptive field of a retinal ganglion cell is the region of the retina occupied by the photo receptors to which the retinal ganglion cells connected
Centre surround receptive field
A retinal ganglion cell receptive field in which the centre of the receptive field responds differently to stimulation than the surrounding portion of the field
On centre receptive fields
Receptive fields of RGC With centres around structure in which the RGC increase their firing rate when the amount of light striking the centre of the receptive field increases relatively to the amount of light striking list around
Preferred stimulus
The type of stimulus that produces endurance maximum firing rate, for our GC with on centre receptive fields, the preferred stimulus is a spot of light that exactly fills the centre of the receptive field
Off-center receptive fields
Receptive fields of retinal ganglion cells with centres around structure in which the retinal ganglion cells decrease their firing rate when the amount of light striking the centre of the receptive field to Chris’s relative to the amount of light striking the surround
Edge enhancement
A process by which the visual system makes edges as visible as possible, facilitating perception of where one object or surface ends in the retinal image and another begins
Strabismus
A disorder of the extra ocular muscles in which the two eyes are not aligned with one another, resulting in a double image, which impairs binocular depth perception
Amblyopia
A condition in which both eyes develop normally but the neural signals from one I order processed properly, so that find a vision doesn’t develop in that eye
Myopia (or nearsightedness)
A condition in which the optic access is too long and accommodation cannot make the lens good enough to focus light from a distant objects on the retina, so the light comes to a focus in front of the retina, and the image on the retina is blurry. The person can see nearby objects clearly but not distant objects
Hyperopia (farsighted)
A condition in which the optic access is too short and accommodation cannot make the lens thick enough to focus light from a nearby objects on the retina, so the light comes to focus behind the retina image on the retina is blurry the person can see distant objects but not nearby objects
Presbyopia
The lens becomes less elastic with age, characterized by a progressive increase in distance from the eye to the near point as a person ages, as hyperopia accommodation can’t make the lipstick enough to focus light on nearby objects
Near point
The closest distance at which a person can bring an object into focus, presbyopia is characterized by progressive increase in the distance from the eye to the near point as a person ages
Astigmatism
A condition in which the curvature of the cornea or lens is slightly irregular asymmetrical, making it impossible for the lens to fully accommodate
Cataract
A progressive “clouding” of the lens that can, if left untreated, lead to blindness
Glaucoma
A condition in which the inter-ocular pressure is too high for the persons I, most commonly caused by blockage of an opening that let aqueous Humour drain from the anterior chamber
Floaters
Shadows on the retina thrown by debris within the virtuous humor, perceived a small semi transparent spots or threats that appear to be floating before the persons eye and intend to move with the eyes
Phosphenes
Brief, tiny bright flashes in the person’s field of you not caused by late but by any of a variety of other causes
Macular degeneration
A condition characterized by damage to the photo receptors in a region at the centre of the retina the leading cause of severe visual loss in the USA
Retinitis Pigmentosa (RP)
On inherited condition in which there is gradual to generation of the photo sceptres over many years, after meeting to night blindness and tunnel vision
