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sensation and perception > chapter 3 > Flashcards

chapter 3 Flashcards

1
Q

vision is the sensory system that allows us to perceive….

A

light

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2
Q

light

A
  • electromagnetic energy
  • made up of photons
  • wavelength
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3
Q

electromagnetic energy

A
  • form of energy that includes light, both a wave and a particle
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4
Q

wavelength

A
  • distance between two adjacent peaks in a repeating wave, different forms of electromagnetic energy are classified by their wavelengths
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5
Q

intensity in reference to waves

A
  • height of a wave
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6
Q

frequency

A
  • number of waves per unit of time, frequency is the inverse of wavelength
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7
Q

the shorter the wavelength is…

A

the higher the energy is

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8
Q

electromagnetic spectrum

A
  • the complete range of wavelengths of light and other electromagnetic energy
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9
Q

photon

A
  • a single particle of light
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10
Q

how humans see light

A
  • light emanates from a light source
  • light falls on objects in an environment
  • those wavelengths reflected by the objects
  • reflected light enters the eye through the pupil, focused on the retina by the cornea and lebns
  • rods and cones in the retina transduce light energy into an electrochemical signal
  • sent to the brain processing through the optic nerve
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11
Q

cornea

A
  • clear front surface of the eye that allows light in
  • major focusing element
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12
Q

sclera

A
  • outside surface of the eye
  • protective membrane covering the eye
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13
Q

anterior chamber

A
  • fluid filled space between the cornea and the iris
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14
Q

iris

A
  • muscle that controls the amount of light entering through the pupil
  • colored part of the eye
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15
Q

pupil

A
  • an opening in the middle of the iris
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16
Q

pupillary reflex

A
  • automatic process by which the iris contratcs or relaxes in response to the amount of light entering the eye
  • the reflex controls the size of the pupil
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17
Q

heterochromia

A
  • one person has irises of 2 different colors
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18
Q

posterior chamber

A
  • space between the iris and the lens, filled with aqueous humor
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19
Q

the lens

A
  • located behind the iris
  • adjustable focusing element of the eye
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20
Q

accommodation

A
  • process of adjusting the lens of the eye so that you can see near and far objects clearly
  • controlled by ciliary muscles
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21
Q

ciliary muscles

A
  • work with zonule fibers connecting the lens to the choroid membrane
  • contract, increasing curvature of the lens, lens thickens, focus close
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22
Q

presbyopia

A
  • incoming light focuses behind the retina
  • difficulty close up objects
  • lens becoming less flexible as you age
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23
Q

retinal image

A
  • light projected onto the retina
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24
Q
  1. retina
A
  • innermost of the three membranes in the eye
  • paper thin layer of cells at the back of the eye where transduction takes place
  • designed to help photoreceptors capture light
  • starts the process of transmitting visual information to the brain
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25
Q
  1. photoreceptors
A
  • cells at the back of the eye
  • photoreceptors synapse ( connect) with two types of cells, horizontal and bipolar
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26
Q
  1. bipolar cells
A
  • biopolar cells synapse with amacrine and ganglion cells
  • receive information from photoreceptors
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27
Q
  1. ganglion cells
A
  • send their axons to the optic disc where they exit the eye
  • axons then become the optic nerve carrying the signals from the retina to the brain
28
Q

function:
receptors

A
  • transduce light into a neural signal
28
Q

function
rods

A
  • night vision, light detection, grayscale vision
29
Q

function
cones

A
  • color vision, daytime vision
30
Q

function
horizontal cells

A
  • receive information from photoreceptors and other horizontal cells
  • cross talk across photoreceptors
31
Q

function
amacrine cells

A
  • receive information from bipolar,ganglion cells and other amacrine cells
32
Q

function
retinal ganglia

A
  • recieve information from bipolar cells, send signals to the brain via the optic nerve`
33
Q

rods

A
  • photoreceptors at the periphery of the retina, sensitive to light
34
Q

fovea

A
  • an area on the retina that is dense in cones but lacks rods
  • rods more common at the periphery
35
Q

cones

A
  • photoreceptors in the fovea of the retina, responsible for color
36
Q

macula

A
  • direct center of the retina
  • holds the fovea but is larger than it
37
Q

optic disc

A
  • the point of exit for ganglion cell axons (optic nerve) leaving the eye, no receptor cells
38
Q

photo pigments

A
  • molecule that absorbs light
  • releases an electric potential by altering the voltage in the cell
39
Q

opsin

A
  • protein portion of a photopigment that captures the photon of light and begins the process of transduction
  • variation in opsin determines the type of visual receptor
40
Q

photopigments are composed of (rods)

A
  • opsin in rods
  • vitamin a (retinal
  • rhodopsin
41
Q

photopigments are composed of (cones)

A
  • chromodopsin in cones
  • vitamin a (retinal)
  • similar to rhodopsin but 3 classes
42
Q

hyperpolarization

A
  • change in the voltage of a neuron whereby the inside of the cell becomes more negative than it is in its resting state
43
Q

duplex theory of vison

A
  • functionally two distinct ways in which our eyes work, depending on conditions in the environment
  • photopic, cones
  • scotopic, rods
44
Q

photopic vision

A
  • vision associated with cones
  • daytime, good acuity in the fovea, color vision
45
Q

scotopic vision

A
  • vision associated with rods
  • poor acuity, no color ability
  • sensitive to light
46
Q

spectral sensitivity

A
  • relative sensitivity of a receptor type to all of the wavelengths
47
Q

purkinje shift

A
  • difference im spectral sensitivity with rods and cones
  • shift towards blue side of color spectrum at night
  • as night time conditions appear, longer wavelengths of light will appear darker, shorter wavelengths will appear brighter
48
Q

spatial summation

A
  • multiple presynaptic neurons release neurotransmitters onto a single postsynaptic neuron, combining signals, action potential
  • ability to pool light across different regions of space
  • at night need to detect as much light as possible, a little blurry
49
Q

acuity

A
  • ability to see fine details
50
Q

convergence

A
  • many rods connect to one retinal ganglion cell where their responses are added together
  • allows the scotopic system to pool responses across different rods to maximize sensitivity to light in exchange for less acuity
50
Q

dark adaptation

A
  • sensitivity to low light is increased
  • first 8 minutes cones do most of the seeing
  • dark eyes have concentration of rhodopsin
50
Q

light adaptation

A
  • when light returns, dark adaptation in reverse
  • 5 minutes or less
  • visual systems sensitivity is reduced so that it can operate in higher light levels
50
Q

convergence of photoreceptors onto ganglion cells

A
50
Q

edge detection

A
  • process of distinguishing where one object ends and the next begins
50
Q

receptive field

A
  • area in the visual world that a particular vision neuron responds to
  • array of photoreceptors from which each retinal ganglion cell receives input
50
Q

on center receptive fields

A
  • retinal ganglion cells that increase their firing late (excitation) when light is presented in the middle of the receptive field
  • decrease their firing rate (inhibition) when light is presented outside of the receptive field
  • cells respond to luminance contrast
50
Q

hyperopia

A
  • condition causing an inability to focus on near objects
  • accommodation cannot make the lens thick enough
50
Q

lateral inhibition

A
  • reduction of a response of the eye to light
50
Q

center surround receptive field

A
  • a receptive field in which the centre responds opposite to how the surround of the receptive field responds
  • eg centre, increase activity, outside, decrease activity
50
Q

off center receptive fields

A
  • retinal ganglion cells that decrease their firing late (inhibition) when light is presented in the middle of the receptive field
  • increase their firing rate (excitation) when light is presented outside of the receptive field
50
Q

astigmatism

A
  • irregular shape of the cornea or lens
  • impossible for the lens to accommodate a fully focused image
51
Q

myopia (nearsightedness)

A
  • condition causing an inability to focus clearly on far objects
  • accommodation can’t make the lens thin enough
51
Q

cataracts

A
  • darkening of the lens
51
Q

macular degeneration

A
  • disease that destroys the fovea and the area around it
51
Q

retinitis pigmentosa

A
  • inherited progressive degenerative disease of the retina
  • can lead to blindness`

sensation and perception (8 decks)

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