9 - Vision

Front 1

• Receptors must respond to light energy
• Light energy – small part of electromagnetic energy
• Visible spectrum is 400 nm to 700 nm range
• 2 types of receptors in the retina.
o Rods – 1 type – respond to a wide portion in the visible spectrum. Used when light energy is low (dim light).
o Cones – 3 types – each type of cone has a different but overlapping part of the visible spectrum. (bright light receptors).

Back 1

vision

Front 2

_________ must respond to light energy

Back 2

Receptors

Front 3

small part of electromagnetic energy

Back 3

Light energy

Front 4

Visible spectrum is ____ nm to ____ nm range

Back 4

400 - 700

Front 5

What are the two types of receptors in the retina?

Back 5

rods and cones

Front 6

– 1 type – respond to a wide portion in the visible spectrum. Used when light energy is low (dim light).

Back 6

rods

Front 7

– 3 types – each type of ____ has a different but overlapping part of the visible spectrum. (bright light receptors).

Back 7

cones

Front 8

• As light passes through objects of different densities it is bent (refracted)
• Cornea refracts light the most (can’t use to control light)
• Lens is the most significant structure that refracts light and thus focuses light energy, because it can CHANGE the amount of light refraction it causes.
• Lens changes refraction by changing shape.
• The process of changing lens shape to focus light rays on the retina is called ACCOMMODATION.

Back 8

Optics of vision

Front 9

As light passes through objects of different densities it is _____ or _________.

Back 9

bent
refracted

Front 10

_______ refracts light the most (can’t use to control light)

Back 10

Cornea

Front 11

_____ is the most significant structure that refracts light and thus focuses light energy, because it can CHANGE the amount of light refraction it causes.

Back 11

Lens

Front 12

____ changes refraction by changing shape.

Back 12

Lens

Front 13

The process of changing lens shape to focus light rays on the retina is called _____________.

Back 13

ACCOMMODATION

Front 14

1. Light rays from close objects must be bent more to focus them on the retina.
2. Because light energy strikes the eye at greater angles from close objects.
a. Focusing the image we are most concerned w/on a small area of the retina called the fovea. Why?
i. Fovea has dense pattern of CONES
ii. Provides for visual acuity – ability to see detail

Back 14

accommodation

Front 15

Light rays from close objects must be bent more to focus them on the ______.

Back 15

retina

Front 16

______ _______ strikes the eye at greater angles from close objects.

Back 16

Light energy

Front 17

Focusing the image we are most concerned w/on a small area of the retina called the ______.

Back 17

fovea

Front 18

Why is the image focused on the fovea in the retina?

Back 18

Fovea has a dense pattern of CONES
Provides for visual acuity – ability to see detail

Front 19

• Due to how the photoreceptors are conn. to the visual pathways.
• 1 cone synapses on 1 bipolar cell & each bipolar cell synapses on 1 ganglion cell.
• Each cone has its own direct connection to the CNS. Provides greater detail about visual images.
• Several RODS synapse on a single bipolar cell.
• Several bipolar cells synapse on 1 ganglion cell.
• Thus sensory info sent to the brain is not as detailed when using RODS as the photoreceptors.

Back 19

visual acuity

Front 20

Due to how the photoreceptors are conn. to the visual pathways.

Back 20

visual acuity

Front 21

When does 1 cone synapses on 1 bipolar cell & each bipolar cell synapses on 1 ganglion cell?

Back 21

happens during visual acuity

Front 22

Each ____ has its own direct connection to the CNS. Provides greater detail about visual images.

Back 22

cone

Front 23

Several ____ synapse on a single bipolar cell.

Back 23

rods

Front 24

Several bipolar cells synapse on 1 _________ cell.

Back 24

ganglion

Front 25

Thus sensory info sent to the brain is not as detailed when using _____ as the photoreceptors.

Back 25

rods

Front 26

What is controlled by the 2 sets of smooth muscles w/in the iris of the eye?

Back 26

the regulation of light entering the eye

Front 27

controlled by PNS. Decrease pupil diameter.

Back 27

circular muscles –

Front 28

controlled by SNS : increase pupil diameter

Back 28

Radial muscles –

Front 29

Rods & cones are found in the deepest parts of the _______. Light must pass through all retinal layers before reaching the _____________.

Back 29

retina
photoreceptor

Front 30

1. contain pigments – rhodopsin
2. Rhodopsin composed of a protein portion (an opsin) and a chromophore (retinal).
3. The combination absorbs light in a particular pattern & the effected retinal changes its shape.
4. Initiates a series of chemical reactions
5. Causes the rods to HYPERPOLARIZE (inhibiting)
6. Causes a DECREASE in the amount of Glutamate (inhibitory neurotransmitter) released at the synapse w/ the bipolar cells.
7. causes the bipolar cells to DEPOLARIZE.
8. Bipolar cells release a neurotransmitter (excitatory) that DEPOLARIZES ganglion cells, leading to action potential generation.
9. Action potential then travels through visual pathways to the brain.

Back 30

rod function

Front 31

___________ composed of a protein portion (an opsin) and a chromophore (retinal).

Back 31

rhodopsin

Front 32

Which photoreceptor contains pigments called rhodopsin

Back 32

rods

Front 33

What causes the rods to HYPERPOLARIZE (inhibiting)?

Back 33

a series of chemical reactions

Front 34

• 3 types of _____ , each w/ a different opsin & retinal (photopigment)
o Each opsin bonds differently to retinal
o Thus each type of photopigment responds maximally to different wavelengths of light.
o Therefore, each _____ type responds differently to a given wavelength of light.
o The relative amount of response by a given _____ type to a given stimulus is the major input sent to the brain where color perception is determined.

Back 34

cones

Front 35

______ _______ then travels through visual pathways to the brain.

Back 35

action potential

Front 36

3 types of cones, each w/ a different ______& _______(photopigment)

Back 36

opsin
retinal

Front 37

Each opsin bonds differently to ________.

Back 37

retinal

Front 38

Each type of ___________ responds maximally to different wavelengths of light.

Back 38

photopigment

Front 39

Each cone type responds differently to a given ___________of _____.

Back 39

wavelength
light

Front 40

The relative amount of response by a given cone type to a given stimulus is the major input sent to the brain where ______ __________ is determined.

Back 40

color perception