Unit 8: The Eye

Question 1

electromagnetic energy

Answer 1

-a form of energy that includes light that is simultaneously both a wave and a particle

Question 2

wavelength

Answer 2

-the distance between 2 adjacent peaks in a repeating wave; different forms of electromagnetic energy are classified by their wavelengths

Question 3

field of view

Answer 3

-the part of the world you can see without eye movements

Question 4

cornea

Answer 4

-clear front surface of the eye that allows light in; also a major focusing element of the eye
-rigid, so it can only focus on 1 distance

Question 5

iris

Answer 5

-the colored part of the eye; a muscle that controls the amount of light entering through the pupil

Question 6

pupil

Answer 6

-an opening in the middle of the iris
-dark, pupil dilates which lets more light in
-bright area means that the pupil gets smaller bringing less light in

Question 7

lens

Answer 7

-the adjustable focusing element of the eye, located behind iris

Question 8

retina

Answer 8

• the paper thin layer of cells at the back of the eye where transduction takes place

Question 9

receptors

Answer 9

-transduce light into a neural signal

Question 10

rods

Answer 10

night vision, light detection grayscale vision
-in the periphery

Question 11

cones

Answer 11

high visual acuity, color vision, daytime vision
-in the fovea

Question 12

horizontal cells

Answer 12

-receive information from photoreceptors and other horizontal cells; cross talk across photoreceptors

Question 13

bipolar cells

Answer 13

-receive information from photoreceptor; send signals to retinal ganglion cells

Question 14

amacrine cells

Answer 14

-receive information from bipolar cells and other marine cells; cross talk function

Question 15

retinal ganglia

Answer 15

-receive information from bipolar cells; send signal to Brain via the optic nerve

Question 16

optic disc

Answer 16

-the part of the retina where the optic nerve leaves the eye and heads to the brain; along the optic disc

Question 17

photopigment

Answer 17

• a molecule that absorbs light and by doing so releases an electric potential by altering the voltage in the cell
  -contained in discs within rods and cones

Question 18

hyperpolarization

Answer 18

-a change in voltage of a neuron whereby the inside of the cell becomes more negative than in its resting state

Question 19

duplex theory of vision

Answer 19

-2 distinct ways in which our eyes work, the photopic, associated with the cones, and the scotopic associated with the rods

Question 20

The Photopic System

Answer 20

-vision associated with the cones; it is used in the daytime, has good acuity in the fovea and has color vision

Question 21

The scotopic vision

Answer 21

associated with rods

Question 22

receptive field

Answer 22

-a region of adjacent receptors that will alter the firing rate of a cell that is higher up in the sensory system

Question 24

center-surround receptive field

Answer 24

-a receptive field
-the center of the field responds opposite to how the surround of the receptive field responds
-if the center responds with an increase of activity to light then the surround responds with a decrease in activity to light

Question 25

on-center receptive field

Answer 25

-the center produces excitation, whereas the surround produces inhibition

Question 26

off-center receptive field

Answer 26

• the center produces inhibition, whereas the surround produces excitation

Question 27

myopia

Answer 27

-near sightedness
-can focus well on near objects
-problems in usually both eyes
-the eye tends to be too long from front to back for the lens

Question 28

hyperopia

Answer 28

-a condition causing an inability to focus on near objects, also called farsightedness
-occurs because accommodation cannot make the lens thick enough
-focus behind retina

Question 29

Astigmatism

Answer 29

-develops from an irregular shape of the cornea or an irregular shape of the lens
-impossible for the lens to accommodate a fully focused image

Question 30

Cataracts

Answer 30

-clouding of the lens
-affect older adults
-due to water build up
-can lead to blindness

Question 31

macular degeneration

Answer 31

-destroys the fovea and area around it
-occurs in 2 forms: wet and dry
-dry: takes years and no treatment
-wet: fast onset, less common, and partially treatable

Question 32

Retinitis Pigmentosa

Answer 32

• inherited progressive degenerative disease of the retina that may lead to blindness
  -tunnel vision