Vision Flashcards
What is the general process of sensation?
1) Stimuli in the environment impinge on a sensory receptor ( reception)
2) The sensory receptor alters its membrane potential in response (transduction)
Light
electromagnetic radiation travelling in waves
Wavelength
horizontal distance b/t 2 consecutive troughs/crests
Amplitude
vertical distance/height b/t the tip of a crest and the wave’s central axis
Frequency
the number of full wavelengths that pass by a given point in space every second
What is the physical component of hue?
wavelength/frequency
What is the physical component of brightness?
intensity/amplitude
What is the physical component of saturation?
purity
Hue
the visible spectrum and colors that we can name
Brightness
relative lightness or darkness of a particular color
Saturation
relative purity of light being perceived
Extraocular muscles
allow for the movement of the eyes
Movement: Vergence
cooperative movement that keeps both eyes on the same target
Movement: Saccadic
jerky movements as the gaze shifts abruptly
Movement: Pursuit
smoother movements that the eyes can make while following something
Sclera
white outer layer of most of the eye
Cornea
outer layer at the front of the eye
Iris
Pigmented ring of muscles behind the cornea
pupil
opening of the iris
Conjunctiva
mucous membrane that lines eyelid and folds back to attach to the eye
lens
series of transparent, onion-like layers
Ciliary muscles
change the shape of the lens through contractions
optic disk
where visual info axons gather and leave the eye via the optic nerve
Retina
inner lining of the eye
fovea
central region of the retina; where visual activity is the highest
Vitreous Humor
clear, gelatinous substance in the eye
Retina layers
eye, ganglion cell layer, bipolar cell layer, photoreceptive layer
Bipolar cell layer
has bipolar cells, horizontal cells, and amacrine cells
Photoreceptive layer
has rods and cones
Transduction
1) light comes in through the cornea and pupil and hits the lens, the lens focuses the light and projects it onto retina.
2) photoreceptors receive the light information and spread info to the bipolar cells then the ganglion cells
3)the ganglion cells generate action potentials
4) the axons of all the ganglion cells weave together to form the optic nerve
5) optic nerve leaves the back of the eye and carries impulses to the thalamus and the to the brain’s visual cortex
rods (7 things)
useful in lowlight conditions; monochromatic information; more sensitive to light; in the periphery; lots in the retina; many rods may connect to one ganglion cell
cones
fine detail and color; red green and blue sensitive; fewer cones in the retina; each cone connects to one ganglion cell
photoreceptors
absorb light;
Photopigments two parts
opsin (a protein) and retinal (a lipid)
Receptive field: fovea
provides more acute visual information, one-to-one ganglion cells and cones
Receptive field: periphery
many receptors converge on a single ganglion cell; less precise
How are stimuli conveyed through the brain?
Through the optic nerves
Information from the inner retina does what?
crosses the optic chiasm and and ascends to the opposite side of the brain
Information from the outer retina does what?
remains on the same side of the brain
