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Flashcards in Vision: Physiology Deck (25):
1

If light rays are absorbed, not reflected, by an object, what do we see?

Dark object

2

If light rays of many wavelengths are reflected off an object, what do we see?

White object

3

If red light rays are absorbed, but blue one are reflected, what do we see?

Blue object

4

What is LIGHT?

Packets of energy travelling in wavelike fashion at high speed (300,000 km/s)

5

How fast does LIGHT travel through less dense materials?

Very fast

6

How fast does LIGHT travel through dense material?

Slowly

7

How fast does LIGHT travel through more dense materials?

Slower

8

What does "refraction" mean?

LIGHT is bending

9

How does the density of an object affect refraction?

The more dense, the more it refracts

10

How will LIGHT RAYS from a distant object arrive at your eye?

They will arrive in parallel lines (see notes for a pic)

11

How will LIGHT RAYS from a close object arrive at your eye?

They will diverge (see notes for a pic)

12

Where does 75% of REFRACTION occur?

In the CORNEA

13

Why does most REFRACTION occur at the CORNEA?

Because the biggest difference in density occurs between air (1.00) and the CORNEA (1.38), and more density = more REFRACTION

14

Where does 25% of REFRACTION occur?

At the LENS

15

Why is there less REFRACTION at the LENS than there is at the CORNEA?

Because the difference in density between the AQUEOUS HUMOR (1.33) and the LENS(1.40) is much smaller than the difference of density between air and the CORNEA

16

Can the REFRACTIVE power of the CORNEA ever change?

No, because the shape of the CORNEA is unchanging

17

Can the REFRACTIVE power of the LENS ever change?

Yes, because the LENS can change shape

18

When is the REFRACTIVE power of the LENS *decreased*?

When the LENS is *flat*

19

When is the REFRACTIVE power of the LENS *increased*?

When the LENS is *round*

20

Are our eyes preset for close-up vision?

No, they are preset for distant vision

21

What is happening to structures inside the eye when focusing on a distant object?

CORNEA = unchanging (refracts LIGHT)
LENS = flat (refracts LIGHT)
NEURONS = sympathetic
CILIARY MUSCLES = relaxed, dilated
CILIARY ZONULE = pulled taut

22

What is BINOCULAR VISION?

Parallel RAYS can land on FOVEA when eyes face forwards

23

Why do PUPILS dilate when focusing on a distant object?

To allow more parallel LIGHT RAYS in

24

What stimulates the PUPILLARY DILATOR MUSCLES to allow more LIGHT in?

The sympathetic system

25

In distant vision, when the PUPILLARY DILATOR MUSCLES contract, the
_________ ___________ _______ are
____________ ____.

PUPILLARY CONSTRICTOR MUSCLES
relaxed/pulled open