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Flashcards in Problem 2 Deck (61)
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1

Cornea

transparent

--> most light photons are transmitted through it
(deutsch - Hornhaut )

--> accounts for 80% of the eyes focusing power

2

Aqueous Humour

fluid derived from blood

--> fills the space immediately behind the cornea

3

Iris

- Gives the eye its distictive color

- controls the size of the pupil

--> the amount of light that reaches the retina

4

Pupil

A hole in the iris

--> light enters here

5

Lens

Shape of it is controlled by the ciliary muscles

--> enables the changing of focus

--> accounts for 20% of the eyes focusing power

6

Vitreous Humour

Transparent fluid that fills the vitreous chamber in the posterior part of the eye

7

Retina

Is the network of neurons that covers the back of the eye

--> contains rods and cones

8

Optic Disc / Blind Spot

The point where

1. the arteries + veins that feed the retina, enter the eye

2. the axons of ganglion cells leave the eye

3. there are no photoreceptors

9

Anatomy of rods and cones

1. outer segment --> adjacent to pigment epithelium

2. inner segment --> cell body

3. synaptic terminal --> contain connections to horizontal + bipolar cells

10

Peripheral retina

Includes all of the retina outside of the fovea

--> contains both rods and cones (S cones)
--> used when detecting + localizing stimuli that we aren't looking at directly

ex.: seeing a moving truck out of the corner of the eye

11

Opsin

Its structure determines which wavelengths of light the pigment molecule absorbs

12

Rhodopsin

Pigment that is found in rods

13

Ciliary muscles

Increase the focusing power of the lens by increasing the lens curvature

14

Accomodation

Change in the lens shape that occurs when the ciliary muscles tighten

--> this increases the curvature of the lens so that it gets thicker

15

Why is accommodation necessary ?

The increased curvature of the lens increases the bending of the light rays, pulling the focus point back to Point A

--> image is not blurred anymore

16

Near point

Distance at which the lens can no longer accommodate to bring close objects into focus

17

Presbyopia

Increasing distance of the near point as one gets older

- loss of this ability occurs because

a) lens hardens with age
b) ciliary muscles become weaker

18

Myopia / Nearsightedness

Inability to see distant objects clearly

--> myoptic optical system brings parallel light into focus at a point in front of the retina ( result : blurred image)

19

What are possible causes of Myopia ?

1. Refractive myopia

--> cornea or lens bend the light too much

2. Axial myopia

--> eyeball is too long

20

What are solutions for Myopia ?

1. Moving objects closer

2. Corrective glasses

3. Surgical procedure

21

Far point

Distance at which light becomes focused on the retina

22

Hyperopia / Farsightedness

Inability to see near objects clearly

--> focus point for parallel rays of light is located behind the retina

23

What is the cause of Hyperopia ?

Too short eyeball

24

Solution for Hyperopia ?

Corrective glasses

25

Functions of Visual pigments

1. Trigger electrical signals

2. Determine our ability to see dim light + light in different parts of the visual system

26

What are the components of a visual pigment ?

Opsin --> long protein

Retinal --> small, light sensitive component

27

Isomerization

Describes the retinals change of shape when the visual pigment molecule absorbs one photon of light

28

Dark adaptation

The process of increasing sensitivity in the dark

--> rod and cone receptors adapt to the dark at different rates

29

Fovea

small area on the retina, contains only cones

--> image falls on fovea when we look directly at an object

--> specialized for seeing fine details

(M + L cones)

30

Macular degeneration

condition that destroys the fovea and a small area surrounding it

--> results in a blind region in central vision