Vision

Question 1

Pupil

Answer 1

The opening in the center of the iris.

Question 2

Lens

Answer 2

Adjustable

Question 3

Cornea

Answer 3

Not adjustable

Question 4

Retina

Answer 4

The rear surface of the eye, which is lined with visual receptors. Light from the life strike the right half, and vice versa

Question 5

Rods

Answer 5

Abundant in periphery of the human retina, respond to faint light but are not useful in daylight because bright light bleaches them.

Question 6

CONES

Answer 6

Abundant in and near the fovea, are less active in dim light, more useful in bright light, and essential for color vision.

Question 7

FOVEA

Answer 7

A tiny area specialized for acute, detailed vision

Question 8

BIPOLAR CELLS

Answer 8

Locate at the center of the eye. receive message from the receptors at the bank of the eye and send their message to ganglion cells

Question 9

GANGLION CELLS

Answer 9

Located still close to the center of the eye. Their axon join together and travel back to brain.

Question 10

BLIND SPONT

Answer 10

(see fig 6.4) the ganglion cell axon join to from the optic nerve that exits through a point at the back of the eye. ( also blood vessel) it has no receptors.

Question 11

OPTIC NERVE(TRACT)

Answer 11

It is a continuation of the optic nerve that relays information from the optic chiasm to the ipsilateral lateral geniculate nucleus (LGN), pretectal nuclei, and superior colliculus.

Question 12

PHOTOPIGMENTS

Answer 12

both rod and cones contain photopigments, chemicals that release energy when struck by light. Photopigments consist of 11-cis-retinal (a derivative of vitamin A) bound to proteins called opsins, which modify the photopigments’ sensitivity to different wavelengths of light. (this closes Na channels in the rod and cones ) (hyperpolarizes the receptor cell)

Question 13

LAW OF SPECIFIC NERVE ENERGIES

Answer 13

Johannes Muller

Whatever excites a particular nerve establishes a special kind of energy unique to that nerve.

Question 14

trichromatic theory

Answer 14

color is perceived through the relative rates of response by three kinds of cones

Question 15

opponent-process theory

Answer 15

problem-negative color afterimages

color is perceived in term of cones that work as paired opposites- red vs. green, yellow vs. blue, white vs. black

Question 16

RETINEX THEOTY

Answer 16

The word “retinex” is a portmanteau formed from “retina” and “cortex”, suggesting that both the eye and the brain are involved in the processing.
when infor from the various parts of thee retina reaches the cortex, the cortex compares each of the inputs to determent the brightness and color perception for each area.
first 2 theories don’t explain color constancy- the ability to recognize the color of an object despite changes in lighting.

Question 17

color vision

Answer 17

visible wavelengths range from about 400 nm (violet) to about 70 nm (red)

Question 18

color vision deficeiencies

Answer 18

red-green color deficiency is most common (8% of men only 1% of women).
A gene causes the long and medium wavelength cones to make the same photopigments instead of different one. Gene is on the X chromosome.