Visual System Part 1

Question 1

Sensory transduction

Answer 1

process by which information about stimuli are communicated into and throughout the brain

Question 2

Conjuctiva

Answer 2

thin membrane covering the eye that extends to the inner eyelids

Question 3

cornea

Answer 3

transparent membrane that refracts and focuses light onto the retina

Question 4

What are the six sets of extraocular muscles?

Answer 4

superior/inferior rectus
lateral/medial rectus
superior/inferior oblique

Question 5

Iris

Answer 5

ring of tissue that surrounds the pupil

it contrasts and expands to limit or increase the amount of light entering the eye

Question 6

Sclera

Answer 6

connective white tissue around the iris

Question 7

Lens

Answer 7

Clear tissue that focuses light onto the retina

shape can be adjusted

Question 8

Cilliary muscle

Answer 8

muscle that can flatten or make the lens more round

Question 9

Accommodation

Answer 9

adjusts shape of lens to focus image onto retina

Question 10

Hyperopia

Answer 10

when the focal point is behind the lens, causes far sightedness

Question 11

Myopia

Answer 11

focal point is infront of the lens, causes near-sightedness

Question 12

Vitreus humor

Answer 12

clear gel-like liquid in the eyeball

Question 13

Retina

Answer 13

layer of the eye that is the most back and where light is detected

Question 14

Fovea

Answer 14

Area of the retina which contains the most cones

Question 15

Optic nerve

Answer 15

axons that exist from the eye and to the brain

Creates a blindspot

Question 16

What are the order of optic nerve cells

Answer 16

retinal ganglion cells, amacrine cells, bipolar cells, horizontal cells, cones, and rods

Question 17

Cones

Answer 17

active when there is light and detects colour and detail

few cones converge on one ganglion cell

Question 18

Rods

Answer 18

active in low light conditions but cannot detect colour or detail
many rods converge on one ganglion cell

Question 19

How do photoreceptors detect light?

Answer 19

light activates rhodopsin and the opsin binds to transducin which activates an enzyme that breaksdown cGMP which is responsible for keeping the sodium ion channel open
This hyperpolarizes the cell and no glutamate is released

Question 20

What if there is no light?

Answer 20

cGMP keeps the sodium channel open and there is glutamate released, which depolarizes the cell slightly

Question 21

Purkinje effect

Answer 21

the idea that red and yellow colours are brighter than blue and green in bright conditions even though they are the same shade and vise versa

Question 22

Protanopia

Answer 22

When the red cones are filled with green light detectors

Question 23

Deuteranopia

Answer 23

When the green cones are filled with red light detectors

Question 24

Tritanopia

Answer 24

When there is a breakdown in function of the blue cones

Question 25

Trichromatic theory

Answer 25

colours may be created by mixing various quantities of the three colours together
colour vision occurs because of three different colour receptors in the retina, three different cones which are each responsive to a specific wavelength (yellow-green, green, green-blue)

Question 26

What are problems with trichromatic theory?

Answer 26

Mixing light is additive whereas mixing pigments are subtractive

Question 27

Negative afterimages

Answer 27

produced after a portion of the retina is exposed to an intense visual stimulus

Question 28

Receptive fields

Answer 28

region of visual field that neurons will respond to

each photoreceptor responds to light from a specific location in the visual field