15.1-15.4

Helps maintain the intraocular pressure; located in the anterior part of the eye.

Aqueous humor

Identify the choroid.

B

Identify the layer that contains both a single-celled pigmented layer and a neural layer.

C

Humans can see several thousand shades of color but have cone photoreceptors that are sensitive to only three (perhaps four) wavelengths of light. What is the best explanation for why we see so many colors?

Color perception is achieved by activation of various combinations between the three cone types.

Which of the following is the best explanation for our perception of color?

Cones come in three types, each sensitive to different wavelengths of light.

Ciliary muscles are considered voluntary, skeletal muscle.

False

The anterior chamber of the eye is filled with vitreous humor.

False

The bending of light rays is called reflection.

False

The structure most responsible for focusing light rays that enter the eye.

Lens

Which of the following is true about photoreceptors?

Rods absorb light throughout the visual spectrum but confer only gray tone vision.

Which of the following is the best explanation of why it is difficult to discriminate the color of an object at night?

Rods contain a single kind of visual pigment.

Which of the following is a characteristic of the lens?

The lens focuses light on the retina.

The function of the lens of the eye is to allow precise focusing of light on the retina.

True

The mucous membrane that lines the eyelids and is reflected over the anterior surface of the eyeball is the conjunctiva.

True

The optic disc is forms a blind spot where the optic nerve leaves the eyeball.

True

When we move from darkness to bright light, retinal sensitivity is lost, but visual acuity is gained.

True

Visible light fits between ________.

UV and infrared

In a person who is color blind, which of the following would you most expect to see?

absence of green or red cones in their foveae

Which structure is NOT matched with its function?

ciliary body: focus the pupil

If retinal detachment occurs in the macula lutea, one can predict that there would be a significant loss of ______.

color vision

During close vision, what actions must the eye take to bring an object into focus?

contract the ciliary body

What term refers to the eye's moving medially to track items close at hand?

convergence

Light passes through the following structures in which order?

cornea, aqueous humor, lens, vitreous humor

This image best illustrates an eyeball that is __________.

emmetropic

Area of greatest visual acuity.

fovea centralis

In glaucoma, damage occurs primarily to the ______.

ganglion cells in the retina

The ability to clearly see objects at a distance but not close up is properly called ________.

hyperopia

In theory, cataracts could be prevented by invention of a treatment that would ______.

increase diffusion rates within the lenses

When a person's cold is accompanied by "watery eyes," there is reduced flow of lacrimal fluid directly into the ______.

lacrimal puncta

The elasticity of the lens decreases with age. This leads to which of the following?

less accommodation of the lenses and difficulty focusing on nearby objects

Damage to the medial portion of the optic chiasm, cause by a pituitary tumor, would lead to

loss of peripheral vision

Choose the correctly paired terms.

nyctalopia: night blindness

The sensory layer of the eye.

retina

During dark adaptation ________.

rhodopsin accumulates in the rods

Another name for the primary visual cortex is ________.

striate cortex

The blind spot of the eye is caused by ________.

there are no photoreceptors where the optic nerve leaves the eye

What is the main function of the rods in the eye?

vision in dim light