Ch. 11 Vision

Front 1

sclera

Back 1

a tough conn. tissue
makes up the "white" of the eye

Front 2

cornea

Back 2

front of eye
a transparent structure that allow light to enter the eye.

Front 3

choroid

Back 3

middle layer of the eye
a highly pigmented layer of tissue beneath the sclera.

absorbs light that reaches the back of the eye so that it is not reflected, which cause distortion of the visual image.

Front 4

ciliary body

Back 4

contain ciliary muscles attached to the lens by strands of conn. tissue called zonular fibers.

Front 5

zonular fibers

Back 5

attached to the lens by strands of conn. tissue called ________ ______.

Front 6

lens

Back 6

focuses the light on the retina where the visual info is transduced.

Front 7

ciliary muscles

Back 7

change the shape of the lens to focus light waves.

Front 8

pupil

Back 8

a hole in the center of the iris that allows light to enter the post. part of the eye
it is NOT a structure

Front 9

iris

Back 9

regulates the diameter of the pupil, thereby regulating the amount of light that reaches the back of the eye.

Front 10

middle layer

Back 10

The ________ _______ of the eye consists of the choroid, ciliary body, and iris.

Front 11

retina

Back 11

The innermost layer of the eye is the ______.

Front 12

retina

Back 12

consists of neural tissue
contains photoreceptors
functions as phototransduction

Front 13

Photoreceptors

Back 13

cells that detect light waves
two types, rods and cones

Front 14

Phototransduction

Back 14

the conversion of light energy to electrical energy.

Front 15

fovea

Back 15

where light from the center of the visual field strikes.
The area of the retina w/ the greatest visual actuity

Front 16

Optic disk

Back 16

the portion of the retina where the optic nerve and blood vessels supplying the eye pass through the retina.

Front 17

blind spot

Back 17

there are no photoreceptors in the optic disk
a reion where light striking the retina cannot be transduced into neural impulses and cannot be perceived.

Front 18

ant. cavity
aqueous humor

Back 18

In front of the lens and ciliary body is the called the ________ _______ containing a clear, watery fluid called __________ ______, which supplies nutrients to the cornea and lens.

Front 19

vitreous chamber
vitreous humor

Back 19

Behind the lens and ciliary body is the __________ ________ containing a firmer, jellylike material called _________ ______, which maintains the spherical structure of the eye.

Front 20

electromagnetic waves

Back 20

Light is a form of energy. Light exists as ________________ ______.

Front 21

reflection

Back 21

a phenomenon in which light waves strike and bounce off a surface.

important in vision because much of the light we perceive has reflected off the objects we are observing.

Front 22

refraction

Back 22

the bending of light waves as they pass through transparent materials of different densities.

its path from objects to the photoreceptors in the retina, light must pass through several different materials, including air, cornea, the lens, and the vitreous and aqueous humor.

Front 23

focal point

Back 23

the convex lens causes the light waves to converge at a single point called the ______ ______.

Front 24

focal length

Back 24

The distance from the long axis of the convex lens to the focal point is called the _______ _______.

Front 25

Concave

Back 25

surfaces cause a divergance of light waves

Front 26

Convex

Back 26

surfaces cause convergence of light waves to a focal point.

Front 27

visual field

Back 27

what we are looking at
must converge at a single point on the retina.

Front 28

rounder

Back 28

When viewing close objects, the lens becomes ________, increasing its refractive power to focus the image on the retina.

Front 29

parallel

Back 29

When viewing something far away, the light waves enter the eye almost ________ to each other, so little refractive power of a rounder lens is needed to focus the light on the retina.

Front 30

Accomodation

Back 30

reflex adjustments of the eye to view near objects

including rounding of the lens, constriction of the pupil, and post. movement of the lens.

Front 31

accommadation

Back 31

under control of the parasympathetic nervous system, which triggers contraction of the ciliary muscle for near vision.

Front 32

myopia

Back 32

nearsightedness

a person can see near objects clearly, but not distant objects because the lens or cornea is too strong for the length of the eyeball and therefor bends light rays too much.

close-up objects can be focused w/out accommadation, but light from distant objects is focused in from of the retina, resulting in a blurred image.

Front 33

hyperopia

Back 33

farsightedness

the lens or cornea is too weak for the length of the eyeball.

distant objects can be focused only w/ accommadation, which means that the lens cannot increase accommadation enough to adjust for near vision.

Light from close-up objects comes to focus behind the retina, resulting in a blurred image.

Front 34

emmetropia

Back 34

normal vision
a person can see both distant and close up objects clearly becuase the eye can focus light from far sources without accommadation, and from near sources w/ accomadation.

Front 35

astigmatism

Back 35

irregularities on the surface of the cornea or lens cause erratic bending of light waves.

Front 36

presbyopia

Back 36

a hardening of the lens that occurs w/ aging; as the lens hardens, its loss of elasticity decreases its ability to become spherical, making accommadation for near vision more difficult.

Front 37

cataract

Back 37

an age-related discoloration of the lens that decreases its transparency.

Front 38

glaucoma

Back 38

increase in the volume of aqueous humor raises pressure in the ant. carity of the eyeball, which can distort the shape of the cornea and shift the position of the lens.

Front 39

myopia

Back 39

_________ can be corrected by using a concave lens to produce divergence of light waves before they enter the eye.

Front 40

hyperopia

Back 40

_________ can be corrected by using a convex lens to produce convergence of light waves that supplements the convergence produced in the eye.

Front 41

circular muscle
(constrictor muscle)

Back 41

form concentric rings around the pupil
when they contract, the diameter of the pupil decreases.

Front 42

pupillary contriction

Back 42

The contraction of the circular muscles cause __________ __________.

Front 43

radial muscles

Back 43

dialator muscle
are arranged like spokes in a wheel
When they contract, the diameter of the pupil increases
leads to pupillary dialation.

Front 44

parasympathetic neurons

Back 44

___________ _______ innervate the circular muscles, which leads to pupillary constriction.

Front 45

sympathetic neurons

Back 45

____________ ________ innervate the radial muscles, which leads to pupillary dialation.

Front 46

Rods

Back 46

provide the ability to see in black and white during relatively low light conditions, such as the light provided by the moon at night.

Front 47

Cones

Back 47

provide us with color vision, but they are active only relatively bright light, such as the sunlight during the day.

Front 48

retina

Back 48

1. an inner layer containing neurons called ganglion cells
2. a middle layer containing neurons called bipolar cells
3. an outer layer containing rods and cones.

amacrine cells & horizontal cells(communication btwn cells in the retina)

Front 49

Macula lutea

Back 49

a depression in the center of the retina that surrounds the fovea.

Front 50

fovea

Back 50

The ______ contains cones only; the ratio of rods to cones increases w/ distance from the ______, until at the periphery of the retina only rods are present.

Front 51

phototransduction

Back 51

the conversion of light energy into elecrical signals, is carried out by the rods and cones.

Front 52

outer and inner segments

Back 52

The two types of photoreceptors is the same; each consists of 2 major portions referred to as _______ and ________ _________.

Front 53

outer segment

Back 53

contains invaginations w/membranous disks that contain the molecules that absorb light waves, giving the photoreceptors the ability to respond to light.

Front 54

inner segment

Back 54

contains the cell nucleus and various organelles and ends at the receptor's synaptic terminal, which is anaglogus to an ordinary neuron's axon terminal and is where a chemical messenger is stored in synaptic vesicles.

Front 55

photopigment

Back 55

absorption of light is the first step in phototransduction, and the molecule in the photoreceptors that absorbs light

Front 56

retinal
opsin

Back 56

Each photopigment molecule contains a light-absorbing portion called _______ and a protein called an _______.

Front 57

retinal
opsin

Back 57

The _______ portion is the same in all photopigments, but the kind of ______ present determines which light wavelengths are absorbed by a given photopigment by altering the electromagnetic energies to which the retinal is sensitive.

Front 58

high

Back 58

Is the degree of convergence w/ bipolar cells in rods high or low?

Front 59

low

Back 59

Is the degree of convergence w/ bipolar cells in cones high or low?

Front 60

at the periphery of retina

Back 60

Where is the site of greatest concentration in the rods?

Front 61

in the fovea

Back 61

Where is the site of greatest concentration in the cones?

Front 62

low

Back 62

What is the visual actuity for rods?

Front 63

high

Back 63

What is the visual actuity for cones?

Front 64

high

Back 64

Do rods have a high sensitivity or a low sensitivity to light?

Front 65

low

Back 65

Do cones have a high sensitivity or a low sensitivity to light?

Front 66

rods
rhodopsin

Back 66

When exposed to bright light, the ____ become "bleached"; that is, most of the ___________ has absorbed light, and the opsin in in its active form. No more light can be absorbed until the ___________ has been returned to original (bleached) state.

Front 67

unbleached

Back 67

____________ rods are extremely sensitive to light.