Vision (183-208)

Question 1

Scotoptic vision

Answer 1

Monochromatic vision produced through the rods in low light.

Question 2

Photopic vision

Answer 2

Chromatic vision produced through the cones under well-lit conditions.

Question 3

Dark current

Answer 3

Continuous inflow of Na+ and Ca++ into rods and cones in the dark through cGMP-regulated channels, causing hypo polarization and glutamate release.

Question 4

Hemidecussation

Answer 4

A partial crossing of optic fibers in the chiasma opticum ensuring that information collected from the same part of the visual field by the two retinas is analyzed in the same hemisphere.

Question 5

Optical illusion

Answer 5

Distortion of visual perception at the cortical level caused by previous experiences.

Question 6

Sclera

Answer 6

The outmost, white layer of the eyeball.

Question 7

Cornea

Answer 7

The frontal, transparent part of the sclera with the highest refracting power.

Question 8

Conjunctiva

Answer 8

A very sensitive epithelial membrane covering the sclera and cornea and lining the inside of the eyelid.

Question 9

Iris

Answer 9

The circular, pigmented membrane behind the cornea, perforated by the pupil. Its contraction regulates the amount of light passing into the eye.

Question 10

Choroid

Answer 10

The middle, vascularized layer of the eyeball, including the iris and the ciliary body (ciliary muscles)

Question 11

Fovea centralis

Answer 11

A depression in the center of the macula of the retina, the area of the most acute vision where only cones are present.

Question 12

Blind spot (optic disk)

Answer 12

The spot on the retina where the axons of the ganglion cells and blood vessels penetrate the wall of the eyeball. No receptors are found here.

Question 13

Musculus ciliaris

Answer 13

The lens is attached to the ciliary body (ciliary muscles) in the eye. Its contraction is needed for accommodation.

Question 14

Glaucoma

Answer 14

An eye disease caused by an excessive intracular pressure due to a disturbance in the production and reabsorption of the aqueous humor.

Question 15

Cataract

Answer 15

An eye disease caused by the opacity of the lens.

Question 16

Presbiopia

Answer 16

In elderly people the lens looses its flexibility, this accommodation is no longer possible for short distances. Is corrected by reading glasses.

Question 17

Cis-retinal

Answer 17

An organic compound derived from vitamin A. In visual pigments it absorbed the energy of photons.

Question 18

Transducin

Answer 18

G-protein in rodes and cones, activated by the photopigment during light detection.

Question 19

Rhodopsin

Answer 19

Photopigment in the rods.

Question 20

Opsin

Answer 20

The protein part of the photopigment.

Question 21

Horizontal cell

Answer 21

Inhibitory interneuron in the retina that connects receptor cells.

Question 22

Amacrin cell

Answer 22

An interneuron in the retina that establishes horizontal connections mostly close to the ganglion cells.

Question 23

Melanopsin

Answer 23

Photopigment contained by the W ganglion cells.

Question 24

M ganglion cell

Answer 24

A ganglion cell projecting to the magnocellular layer of the corpus geniculatum laterale

Question 25

P ganglion cell

Answer 25

A ganglion cell projecting to the parvocellular layer of the corpus geniculatum laterale.

Question 26

Color blindness

Answer 26

Disturbance of color vision causes in most cases by a mutation in the genes coding for the photopigments The most common form is red/green color blindness.