Chapter 2: Beginnings Of Perception Flashcards Preview

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Flashcards in Chapter 2: Beginnings Of Perception Deck (28):
1

What is electromagnetic spectrum?

A continuum of electromagnetic energy that is produced by electrical charges and is radiated as waves

2

What is a wavelength?

Energy described by its wavelength. The distance between the peaks of the electromagnetic waves.

3

Gamma ray and radio wave lengths?

G: 10^-12 meters
R: 10^4 (10000 meters)

4

Eye parts?

Pupil: hole in your eye that lets in light
Cornea: outer layer that covers pupil iris and interior chamber (80% of focusing)
Lens: behind iris, transparent structure that adjusts shape for object distance, other 20% of focus

5

Eye parts 2?

Retina: light-sensitie tissue lining back of eye, has receptors for vision
Sclera: white part of eye

6

Visible light spectrum?

Ranges from 400-700 nanometers.

7

What is the near point?

The distance in which your lens can no longer adjust to being object into focus

8

What is presbyopia?

When the distance of the near point increases with age.

9

Near point focus ages

20 yrs- 10cm
30 yes- 14cm
40yrs- 22cm
60yrs- 100cm

10

What is myopia(nearsided) and what it does?

Inability to see objects far away. Bends light too much. Axial myopia is eyeball too long

11

What is the far point?

Distance at which light becomes focused on retina and can be seen clearly

12

What is hyperopia?

Farsightedness. Trouble seeing close up. Eyeball is too short.

13

Rod anatomy?

Disc: top part of rod
Outer segment: Sheath over head
Inner segment: part between tail and head
Synaptic pedicle: fish tail

14

Molecule name and anatomy?

An opsin, part is retinal
Disc membrane
Disc interior

15

What is Hecht’s psychophysical experiment?

-prior physical evidence showed that it takes one photon to isomerize a pigment molecule
-purpose of experiment is to determine how many pigment molecules beed to be isomerizes for a person to see
-method of constant stimuli used to determine absolute threshold
Results show: a person can see light if seven rod receptors are activated simultaneously

16

What is isomerization?

When a retinal changes its shape

17

Isomerization triggers...

An enzyme cascade. Means a single reaction leads to increasing numbers of chemical reactions.

18

The fovea...

Consists only of cones

19

Peripheral retina has.... and more....

Both cones and rods, more rods than cones

20

Numbers if rods and cones

120 mill rods and 5 mill cones

21

What is macular degeneration?

-fovea and small surrounding area destroyed
-creates blind spots on retina
-common in elderly

22

What is retinitis pigmentosa?

-genetic disease
-rods are destroyed first
-foveal cones attacked maybe
-can cause blindness

23

Rod pigment absorbs best at...

500 nm

24

Cone pigment absorbs best at...

419nm, 531nm, 558nm

25

Absorption of all cones equals peak of...

560nm in spectral sensitivity curve

26

Rods and cones send signals vertically through...

-bipolar cells
-gangelion cells
-gangelion axons

27

Signals are sent horizontally through...

-between receptors by horizontal cells
-between bipolar and between ganglion cells by amacrine cells

28

Rods cannot distinguish detail but are...

-more sensitive to light than cones
-greater convergence which results in sum of inputs of many rods into ganglion cells increasing likelihood of response