Photoreceptors- rods vs cones

Question 1

how many layers does the retina have?

Answer 1

5 layers

Question 2

layers from inside to outside

Answer 2

1. photoreceptors (rods and cones)
2. horizontal cells
3. Bipolar cells
4. Amacrine cells
5. retinal ganglion cells

Question 3

retinal ganglion cells

Answer 3

their axons leave the eyeball and sending visual signals to the CNS
the axon bundle is called the optic nerve

Question 4

What is the functional definition of visual receptors to CNS?

Answer 4

cells that absorb light energy and convert into neural signals

Question 5

why is the blind spot of the retinal blind?

Answer 5

no photoreceptors are found in this part of the retina

Question 6

2 photoreceptors

Answer 6

Rods and Cones

Question 7

Cones

Answer 7

-phototopic (color)
-predominant in bright lighting
-HIGH ACUITY
-mostly located in the center of the retina

Question 8

rods

Answer 8

scotopic vision (black and white)
-predominant in dim lighting
-HIGH SENSITIVITY
-located in the periphery

Question 9

convergence ratio (cones)

Answer 9

central retina (cones)
-comparing receptors between peripheries
-one to one to one ratio
-one cone to one bipolar to one retinal ganglion cell
-high acuity. low sensitivity

Question 10

Convergence ratio (rods)

Answer 10

-temporal periphery (rods)
-many to some to one
-high sensitivity. low resolution

Question 11

visual transduction

Answer 11

-occurs through photo receptors
-photo receptors assault the energy

Question 12

rhodopsin

Answer 12

-light bleaches rhodopsin
-rhodopsin regains the ability to absorb in the dark
-initiates b/w vison

Question 13

what seems odd to you in terms of the configuration of the retinal layer?

Answer 13

Inside out- the receptors are the innermost, further from the light

Question 14

2 visual acuity problems

Answer 14

-incoming light is distorted before it reaches photo receptors
-there is a blind spot

Question 15

we have clear vision because…

Answer 15

of the fovea

Question 16

what is a scotoma?

Answer 16

damage to part of the cortex that causes some area blindness

Question 17

what is perceptual completion?

Answer 17

seeing a figure as complete when it lands on a blind area of the visual field
-explains why many people don’t realize the deterioration of their vision

Question 18

blindsight

Answer 18

forced to guess, some patients respond to stimuli in their scotomas by guessing
-this is because there are alternative visual pathways like the superior colliculus that processes vison.

Question 19

saccades

Answer 19

eye movements
-our eyes do micro movements from one location to another, which explains why we can see pretty well

Question 20

perceive image

Answer 20

the sum of inputs received during the last few fixations