The sense of seeing

Question 1

what is EMR?

Answer 1

electromagnetic radiation

Question 2

define EMR?

Answer 2

a form of radiant energy, propogating through space via electormagnetic waves and or particles called photons

Question 3

what are the 9 components of human eye?

Answer 3

pupil, iris, sclera, cornea, fovea, retina, vitreous, lens, ciliary body

Question 4

what does the iris do?

Answer 4

controlsamount of light that can enter the eye, small and large iris’ ,

Question 5

what does the small iris do?

Answer 5

parasympathetic stimulation of circular muscle

Question 6

what does the large iris do?

Answer 6

sympathetic stimulation of radial muscel

Question 7

what does the cornea do?

Answer 7

provides for most of the refractive power which is measured in dioptre

Question 8

what do the lens do?

Answer 8

can be adjusted for near vision (accomodation)

Question 9

what do concave lens do?

Answer 9

decrease overall refractive power

Question 10

what do convex lens do?

Answer 10

increase overall refreactive power

Question 11

describe distant and near for emmetropia?

Answer 11

d= no acoomodation , focused on retina
near= accomodation , focused on retina

Question 12

what is myopia?

Answer 12

lens of eye too strong for length of eyeball

Question 13

distant and near for myopia?

Answer 13

d= no accomodation, not focused on retins, concave lens for correction
near = no accomodation, focused on retina, with concave lens accomodation occura

Question 14

what is hyperopia?

Answer 14

lens of eye too weak for length of eyeball

Question 15

distant and near for hyperopia?

Answer 15

d= accomodation, focused on retina, convex lens removes accomodation
near= accomodation, not focused on retina, convex lens focuses on retina

Question 16

what causes presbyopia?

Answer 16

near point is nearest distance to eye at which an object is accurately focused on the retina at full accommodation

Question 17

what is scotopic vision?

Answer 17

happens in rods

Question 18

what is photopic vision?

Answer 18

happens in cones

Question 19

5 defining features of rods?

Answer 19

low light levels, not found in the fovea, high sensitivity to light, slow recovery in the dark, no colour vision

Question 20

5 defining features of cones?

Answer 20

day time light levels, high density in the fovea, low sensitivity to light, quick recovery in the dark, colour vision

Question 21

3 components both rods and cones have?

Answer 21

disks, nuclei, SV

Question 22

what is the structure of receptor cells within rods?

Answer 22

consists of stacks of discs, within discs is rhodopsin

Question 23

describe how rhodospin works?

Answer 23

photons are absorbed by specialised molecules in the receptor, receptor is retinal (an 11-cis-isomer), when light hits retinal, it becomes an all-trans-isomer

Question 24

6 components of retinaa?

Answer 24

receptor outer segments, outer nuclear layer, outer plexiform layer, inner nuclear layer, inner plexiform layer and ganglion cell layer

Question 25

what is the ganglion cell layer

Answer 25

retinal gnaglion cells can be provoked by microelectrode

Question 26

what does visual stimulation do to ganglion cells?

Answer 26

without stimulation they show spontaneous activity

Question 27

what are the 2 components of the receptive field of ganglion cells?

Answer 27

an excitatory centre and inhibitory surround

Question 28

what happens when current is passed through ganglion cells?

Answer 28

no. action potentials decreases for inhibitory surround and no. action potentials increases for excritatory centre

Question 29

what are the two types of parallel processing?

Answer 29

P-type and m-type

Question 30

what is p-type processing?

Answer 30

parvocellular and midget cell

Question 31

what is m-type processing?

Answer 31

magnocellular parasol cell

Question 32

what is the transmission to cortex process?

Answer 32

stimulus (normal image) to retinal image (flipped upside down and back to front) to reinotopic map in the left V1 (distorted)