Exercise 22

Eye shine in nocturnal mammals is different from the "red eye" seen in some flash photographs. Eye shine is the reflection from the tapetum lucid. What might produce "red eye?"

bright light reflecting off the back of the retina

suspensory ligaments

cornea

pupil

lens

anterior chamber

sclera

choroid

retina

optic nerve

Since the lens is made of protein, what effect might the preserving fluid used in lab have on the structure of the lens? How would this affect the clarity?

preserving liquid causes the lens to become opaque; protein molecules unwind as they denature and this leads to refraction of light

What is the consensual reflex of the pupil?

increase or decrease of one pupil when the other pupil is exposed to a respective decrease or increase in light

How does the vitreous humor differ from the aqueous humor in location and viscosity?

vitreous humor is in the posterior cavity and is thicker than aqueous humor; aqueous humor is in the anterior cavity and is more watery

What layer of the eye converts visible light into nerve impulses?

retina

What nerve carries the action potentials from the ganglion cells to the thalamus of the brain?

optic nerve

What is another name for the sclera?

white of the eye

How would you define an extrinsic muscle of the eye?

attaches to the sclera and moves the eyeball

What gland produces tears?

lacrimal gland

What is the name of the transparent layer of the eye in front of the anterior chamber?

cornea

The iris of the eye has what function?

control the size of the pupil

Where is vitreous humor found?

in posterior cavity or posterior compartment behind lens

What is the function of the choroid?

blood vessels nourish eye and pigmentation prevents light from scattering/blurring vision

Is the lens anterior or posterior to the iris?

posterior

Which retinal cells are responsible for vision in dim light?

rods

How would you define the near point of the eye?

minimum distance an object can comfortably be held in focus

What do the numbers 20/100 mean for visual acuity?

a person sees at 20 feet what an average individual sees at 100 feet

What is an astigmatism?

a defect in the cornea or lens that causes uneven bending of light rays in that area of the eye (not perfectly smooth)

In what area of the eye is the blind spot located?

at the optic disc

iris

eyelid