Vision and the Eye: Key Concepts

These flashcards cover key concepts related to vision and the anatomy of the eye, providing definitions and explanations for important terms and processes discussed in the lecture.

What is absorption in terms of light energy?

The transfer of light energy to a particle or surface.

Why is there no sensation of light at the optic disk?

Because there are no photoreceptors in the optic disk.

How does aqueous humor differ from vitreous humor?

Aqueous humor lies behind the cornea, whereas the vitreous humor lies between the lens and the retina.

If the cornea has a refractive power of 42 diopters, where are the parallel light rays focused?

0.024 m behind the corneal surface.

Which layer of the retina contains the cell bodies of bipolar, horizontal, and amacrine cells?

Inner nuclear layer.

Which cells in the retina have axons that leave the retina?

Ganglion cells.

What structure accomplishes most of the eye's refractive power?

Cornea.

Why does the fovea appear like a pit in a cross-sectional view?

Because of the lateral displacement of cells above the photoreceptors in the fovea.

What does the term duplex retina refer to?

The retina is capable of both scotopic and photopic vision.

What corresponds to the photoreceptor 'dark current'?

The movement of positive current across the photoreceptor membrane in the dark.

What is a main difference between ON-center and OFF-center ganglion cells?

ON-center ganglion cells receive input from ON bipolar cells, whereas OFF-center ganglion cells receive input from OFF bipolar cells.

What is an example of parallel processing in the visual system?

Simultaneous input from two eyes provides information about depth.

How does the eye focus on objects less than 9 m away?

A change in the shape of the lens in addition to refraction by the cornea.

Which layer contains the light-sensitive elements of the retina?

Photoreceptor layer.

Is the range of wavelengths in the visible electromagnetic spectrum 100–1000 nm?

False.

In signal amplification, is each G-protein activated by a single photopigment molecule?

False.

Does a center-surround receptive field consist of two areas with antagonistic light responses?

True.

Is the sclera the glossy transparent external surface of the eye?

False.

What is the term for the response that causes pupil constriction in both eyes from light shone in one?

Consensual.

In the outer plexiform layer, which types of cells do photoreceptors synapse with?

Bipolar cells and horizontal cells.