The Eye

Front 1

What are the three layers of the eye?

Back 1

Sclera
Choroid
Retina

Front 2

What is the sclera?

Back 2

tough, white tissue except for the cornea which is tranparent

Front 3

What is the choroid?

Back 3

highly vascularized and includes the ciliary body and the iris

Front 4

What is the retina?

Back 4

consists of photoreceptors and pigmented epithelium

Front 5

Do you know what the cornea, anterior chamber, posterior chamber, aqueous humor, vitreous humor, iris, lens, retina, and pigmented epitherlium are?

Back 5

Front 6

Do you know where the cornea, anterior chamber, posterior chamber, aqueous humor, vitreous humor, iris, lens, retina, and pigmented epitherlium all are?

Back 6

Front 7

What is glaucoma?

Back 7

Increase pressure in anterior and posterior chambers due to an accumulation of aqueous humor; pressure is transmitted to the vitreous chamber which reduces blood supply

Front 8

What is the Fovea?

Back 8

In a region of thinned retina known as the macula lutea; thin so that there is minimum distortion. visual acuity due to being exclusively cones

Front 9

What is the optic disc?

Back 9

opening in eye through which blood vessels enter and axons leave; no photoreceptors which results in a blind spot

Front 10

What is Papilledema?

Back 10

swelling of the optic disc as a result of swelling of the brain; can be due to trauma, infection, or tumor

Front 11

What is macular degeneration?

Back 11

loss of photoreceptor cells that is limited to the macula; central vision affected most; dry which is loss of pigmented epithelium and wet which involves abnormal blood vessel growth

Front 12

What is responsible for the focusing of light (refraction)?

Back 12

lens and cornea

Front 13

How does the lens adjust for far vision?

Back 13

thin and flat

Front 14

How does the lens adjust for near vision?

Back 14

thicker and rounder

Front 15

What controls lens shape?

Back 15

ciliar muscles and zonule fibers

Front 16

What are zonule fibers?

Back 16

suspensory ligaments arranged radially to hold the lens in place; attached to lens and to ciliary muscles

Front 17

When ciliary muscles contract what happens?

Back 17

zonule fibers move towards the center of the eye and allow the lens to relax (get thicker); near vision requires contraction (aka accommodation)

Front 18

How does pupil size influence visual clarity?

Back 18

Smaller pupil size increases visual resolution and increases depth of field under normal light conditions

Front 19

What are cataracts?

Back 19

Clouding of the lens that disrupts the passage of light; occur when lens protein degenerates

Front 20

What are the layers of the retina?

Back 20

Pigment epithelium layer
Layer of Photoreceptor outer segments
External limiting membrane layer
Outer nuclear layer
Outer plexiform layer
Inner nuclear layer
Inner plexiform layer
Ganglion cell layer
Optic nerve layer

Front 21

What is the Pigment epithelium layer?

Back 21

Consists of cuboidal cells containing melanin; absorbs any light that doesn't get captured by the photosensitive cells preventing to degradation of the visual signal on the retina and preventing damaging levels of light onto the retina; also provides nutritional support to the photoreceptors

Front 22

What is the reason for retinal detachment?

Back 22

The weak connection between the pigment epithelium and the rest of the retina; leads to a loss of nutritional support

Front 23

Which retinal layer contains bipolar cells?

Back 23

Inner nuclear layer

Front 24

Which retinal layer contains rods and cones?

Back 24

Outer nuclear layer

Front 25

Which layer contains ganglion cells?

Back 25

Ganglion cell layer

Front 26

What is retinitis pigmentosa?

Back 26

Inherited visual disorder caused by progressive loss in vision due to degeneration of photoreceptors; clumps of pigment from pigment layer

Front 27

What are the difference between rods and cones?

Back 27

Front 28

What is the difference between rods and cones?

Back 28

Rods are extremely sensitive to light, but have low resolution.
Cones are relatively insensitive to light, but have high spatial resolution.

Front 29

What level of focus does the cornea provide?

Back 29

Coarse

Front 30

What is the relative distribution of photoreceptive cells in the retina?

Back 30

High density cones in the fovea with rods absent; outside fovea mix of rods and cones with lower density of cones.

Front 31

What photopigment do rods use?

Back 31

Rhodopsin

Front 32

What photopigments do cones use?

Back 32

Violet (short), green (medium), and yellow (long); although each individual cone only uses one type of photopigment.

Front 33

How are we able to detect so many different color with only three photopigments?

Back 33

The visual system is able to compare the relative activities of cones with different photopigments to determine the color of the light.

Front 34

What coding system allows for accurate color vision?

Back 34

frequency coding

Front 35

What is color blindness?

Back 35

lack of cones that contain one of the three pigments; most common is red-green (loss of middle)

Front 36

How do rods and cones respond to light?

Back 36

Graded Changes in membrane potential; this results in hyperpolarization (synaptic transmission stops)

Front 37

Describe the flow of information in the retina?

Back 37

Light strikes the rods/cones --> Hyperpolarizes rods/cones decreasing neurotransmitter release --> bipolar cells are depolarized increasing their neurotransmitter release --> ganglion cells are depolarized and action potentials initiated

Front 38

What is the process of adapting to the overall levels of illumination called?

Back 38

light adaptation

Front 39

What is involved in light adaptation?

Back 39

Cones becoming less sensitive to light (increase in Ca2+ levels); pupil diameter change; neural circuitry changes

Front 40

What are saccades?

Back 40

small movements of the eye that occur when staring at a single image; prevent images from being projected on the same retinal region for too long

Front 41

What is a stabilized retinal image?

Back 41

focusing for a long time on a single image will cause the image to disappear; not normally experienced due to saccades

Front 42

What is myopia?

Back 42

Nearsighted; cannot bring distant objects into focus; caused by cornea being too curved or eye too long

Front 43

what is hypermetropia?

Back 43

Farsighted; cannot bring near objects in focus; caused by the eye being too short

Front 44

What is emmetropia?

Back 44

Normal vision

Front 45

What is astigmatism?

Back 45

Either lens or cornea lacks uniform curvature; light doesn't get focused onto the same point

Front 46

What is one reason older eyes have trouble seeing?

Back 46

elasticity of the lens decreases which results in less accommodation (less round lens --> less near vision)

Front 47

What is presbyopia?

Back 47

When minimal distance at which we can focus upon near object gets farther away; impairs detailed near vision tasks such as reading

Front 48

How is red-green color blindness inherited?

Back 48

X-linked recessive

Front 49

Do bipolar cells have action potentials?

Back 49

no

Front 50

In dark what are rods and cones doing?

Back 50

constantly releasing neurotransmitters that inhibit bipolar cells from releasing neurotransmitters