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ophthalmology > physiology > Flashcards

physiology Flashcards

1
Q

what in the eye senses the optical picture

A

the retina

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2
Q

what is the eye sheltered by

A

bony socket

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3
Q

what act like shutters to protect the eye

A

eyelids

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4
Q

what des spontaneous blinking help

A
  • disperse the lubricating, cleansing, bactericidal tears
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5
Q

what produces the tears

A

lacrimal gland

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6
Q

where is the lacrimal gland

A

upper lateral corner under the eyelid

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7
Q

where do tears drain Into

A

tiny canals in the corner of each eye

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8
Q

where do tears eventually end up

A

in the back of the nasal passageway

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9
Q

how are eyelashes protective

A

they trap fine, airborne debris such as dust before it can fall into the eye

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10
Q

what are the 3 layers of the eye

A
  • sclera cornea - choroid - retina
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11
Q

what is the outermost layer of the eye

A

scleral cornea

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12
Q

what s the tough outer later of connective tissue

A

sclera

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13
Q

what part of the eye is the sclera

A

white part

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14
Q

is the cornea also white

A

no it is transparent

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15
Q

does light pass through the retina

A

yes

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16
Q

what is the layer under the sclera

A

choroid

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17
Q

what is the choroid like

A

pigmented

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18
Q

what does the choroid contain

A

many blood vessels that nourish the retina

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19
Q

what does the choroid become anteriorly

A

ciliary body and iris

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20
Q

what is the innermost layer

A

retina

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21
Q

what does the retina consist of

A

outer pigmented layer and inner nervous tissue layer

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22
Q

what does the nervous tissue layer contain

A

rods and cones

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23
Q

what are rods and cones

A

photoreceptors

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24
Q

what do rods and cones do

A

convert light energy into nerve impulses

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25
Q

what does the interior of the eye consist of

A

two fluid filled cavities separated by an elliptical lens

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26
Q

what does the larger posterior cavity between the Len and retina contain

A

semifluid, jelly like substance = vitreous humour

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27
Q

what does the vitreous humour help maintain

A

spherical shape of the eyeball

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28
Q

what does the anterior cavity between the cornea and lens contain

A

clear, watery fluid = aqueous humour

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29
Q

what does the aqueous humour do

A

carry nutrients for the cornea and lens

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30
Q

how much aqueous humour is produced each day

A

5ml/day

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31
Q

what produces the aqueous humour

A

capillary network within the ciliary body

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32
Q

where is the ciliary body

A

specialised anterior derivative of the choroid layer

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33
Q

where does the aqueous humour from ciliary body drain

A

into a canal = Canal of Schlemm

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34
Q

what happens if the aqueous humour is not drained as quickly as it is produced

A

accumulates in the anterior cavity causing the pressure to rise within the eye

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35
Q

what is it called when the aqueous humour doesn’t drain as quickly as it is made

A

glaucoma

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36
Q

can glaucoma lead to blindness

A

yes

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37
Q

what happens to pupil in bright light

A

constricts

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38
Q

what happens to pupil in dull light

A

dilates

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39
Q

what is the round opening of the iris called

A

pupil

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40
Q

does light enter through the pupil

A

yes

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41
Q

how many types of smooth muscle does the iris contain

A

2

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42
Q

what are the 2 types of smooth muscle

A
  • circular - radial
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43
Q

what are the circular muscle like

A

muscle fibres run in a ringlike fashion within the iris

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44
Q

what are the radial muscles like

A

fibres project outwards from the pupillary margin (like bicycle spokes)

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45
Q

what causes the pupil to constrict

A

the circular muscle contracting

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46
Q

what happens when the radial muscle shorten

A

the size of the pupil increases

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47
Q

what are iris muscles controlled by

A

autonomic nervous system

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48
Q

what nerve fibres innervate the circular muscles

A

parasympathetic (pupillary constriction)

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49
Q

what nerve fibres innervate the radial muscles

A

sympathetic (pupil dialtion)

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50
Q

what is lights individual packets of energy called

A

photons

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51
Q

how do photos travel

A

in wave light fashion 1

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52
Q

what is the distance between 2 wave peaks called

A

wavelength

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53
Q

can the photoreceptors in the eye see all wavelengths

A

nope only those between 400-700

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54
Q

what is the forward movement of a light wave known as

A

light ray

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55
Q

what is the bending of light known as

A

refraction

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56
Q

correlation between curvature and bending

A

the grater the curvature the greater the degree of bending

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57
Q

what way does a convex surface bend

A

outwards

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58
Q

what way does a concave surface bend

A

inwards

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59
Q

what do convex surface move light rays

A

converge them (bring them closer together)

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60
Q

what do concave surfaces do to light

A

diverge light rays (spread them farther apart)

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61
Q

what are concave lenses good for

A

correcting near sightedness

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62
Q

what is astigmatism

A

curvature of cornea is uneven so light rats are unequally refracted

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63
Q

what part of the eye is the ciliary muscle in

A

choroid layer

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64
Q

what are the 2 major components of the ciliary body

A
  • ciliary muscle - capillary network
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65
Q

what does the capillary network produce

A

aqueous humour

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66
Q

what is the ciliary muscle

A

circular ring of smooth muscle attached to the lens by suspensor ligaments

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67
Q

what is the lens like when the ciliary muscle is relaxed

A

lens is flattened

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68
Q

what happens to the lens when the suspensory ligaments are not pulling

A

becomes more spherical

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69
Q

what does the greater curvature of the lens increase

A

the strength, further bending light rays

70
Q

is the lens flat or curved for far vision

A

lens is flat

71
Q

what is the lens like for near vision

A

more convex and stronger for near vision (ciliary muscle contracts)

72
Q

what controls the ciliary muscle

A

autonomic nervous system

73
Q

what causes the ciliary muscle to relax

A

sympathetic

74
Q

what causes the ciliary muscles to contract

A

parasympathetic

75
Q

are the cells in the centre of the eye oldest or newest

A

oldest

76
Q

is the aqueous humour near the centre or edges

A

edges

77
Q

why does your near vision deteriorate first

A

due to the older cells being in the middle and having a poorer blood supply therefore they are lost first causing near vision to fade first

78
Q

what is it called when the elastic fibres re no longer transparent and become opaque

A

cataract

79
Q

can cataract be fixed

A

yes the defective lens can be surgically removed and vision is restored

80
Q

what is nearsightedness called

A

myopia

81
Q

what is farsightedness called

A

hyperopia

82
Q

normal vision is called

A

emmetropia

83
Q

how can myopia be corrected

A

concave lens

84
Q

how can hyperopia be corrected

A

convex lens

85
Q

where does light rays focus

A

on the rods and cones

86
Q

what are the photoreceptors of the retina

A

rods and cones

87
Q

what do the photoreceptors do

A

transform the light energy into electrical signals for transmission to CNS

88
Q

what are the 3 layers of retina

A
  • rods and cones - bipolar cells - ganglion cells
89
Q

what is the outer layer of the retina

A

rods and cones

90
Q

what is the innermost layer of retina

A

ganglion cells

91
Q

what do axons of the ganglion cells join to form

A

optic nerve

92
Q

what is the point on the retina at which optic nerve leaves called

A

optic disc

93
Q

is the optic disc the blind. spot

A

yes

94
Q

can an image be detected at the optic disc

A

no

95
Q

are there rods and cones at the optic disc

A

no

96
Q

where is the point where no light passes

A

fovea

97
Q

where is the fovea

A

pinhead sized depression located in the centre of the retina

98
Q

where is the point of most distinct vision

A

fovea

99
Q

where is the greatest concentration of cones

A

fovea

100
Q

what is the area surrounding the fovea

A

macula lutea

101
Q

what is highly concentrated at the macula lutea

A

cones

102
Q

what is the leading causes blindness in the West

A

macular degeneration

103
Q

what is macular degeneration characterised by

A

loss of photoreceptors in the macula lutea

104
Q

what kind of vision do patients with macular degeneration have

A

doughnut vision (loss of middle vision.)

105
Q

examples of photoreceptors

A

rods and cones

106
Q

what are the 3 parts of photoreceptors

A
  • outer segment - inner segment - synaptic terminal
107
Q

where is the outer segment of the photoreceptors

A

lies closest to the eyes exterior facing the choroid - detects light stimulus

108
Q

where is the inner segment of the photoreceptors

A

lies in the middle of the photoreceptors length

109
Q

where is the synaptic terminal of the photoreceptors

A

lies closest to the eyes interior facing the bipolar cells

110
Q

what shape is the outer segment in rods

A

rod shaped

111
Q

what shape is the outer segment in cones

A

cone shaped

112
Q

what does the outer segment contain

A

abundance of light sensitive photopigment molecules

113
Q

what does photopigment consist of

A
  • opsin - retinal
114
Q

what is opsin

A

integral protein in the disc plasma membrane

115
Q

what its retinal

A

derivative of vitamin A

116
Q

what is the light absorbing part of photopigment

A

retinal

117
Q

what is phototransduction

A

process of converting light into electrical signals

118
Q

do photoreceptors hyper polarise or depolarise when stimulated

A

hyperpolarise

119
Q

what is the photopigment in rods

A

rhodopsin

120
Q

what is retinal in the dark

A

11-cis retinal

121
Q

what is the plasma membrane of photoreceptors outer segment

A

Na+ gated channels that responds to chemical messengers

122
Q

is cGMP high in dark or light

A

dark

123
Q

what is the G protein in rods and cones

A

transducin

124
Q

what does transducin do in the light

A

activate phosphodiesterase

125
Q

what’s more numerous rods or cones at the retina

A

rods

126
Q

what’s more numerous at the macula lutea cones or rods

A

cones

127
Q

as you move out what decreases rods or cones

A

cones decreases from the middle out

128
Q

where are rods most abundant

A

periphery

129
Q

what contain more photopigments rods or cones

A

rods (longer)

130
Q

what have higher sensitivity rods or cones

A

rods

131
Q

what responds to dim light rods or cones

A

rods

132
Q

when are cones activated

A

broad day light

133
Q

what are rods specialised for

A

night vision

134
Q

what are cones specialised for

A

day vision

135
Q

what has higher acuity rods or cones

A

cones

136
Q

what provides sharp vision rods or cones

A

cones

137
Q

what transmits the signal from the photoreceptors

A

ganglion cell

138
Q

what does a ganglion cell needs before it can transit

A

an action potential

139
Q

how does ganglion cell get an action potential

A

by cone cells - one cone to one ganglion cell

140
Q

do cones need lots of light to transmit an action potential

A

yes

141
Q

rods need lots of light true or false

A

false they don’t need a lot of light to cause an action potential

142
Q

do rods share ganglion cells

A

yes

143
Q

what provides colour vision

A

cones

144
Q

how many photopigments in rods

A

one

145
Q

how many photopigments in cones

A

3 - red - green - blue

146
Q

what distinguishes photopigment

A

same retinal different opsin

147
Q

what absorbs the greater spectrum of wavelength

A

rods

148
Q

what is the photopigment in rods

A

rhodopsin

149
Q

what is white colour

A

mixture of all wavelengths

150
Q

what is black colour

A

absence of light

151
Q

what is dark adaption

A

when you go from light to dark initially you can’t see anything then gradually you can

152
Q

what is retinal a derivative of

A

vitamin A

153
Q

why does night blindness occur

A

dietary deficiency of vitamin A

154
Q

where does the left cortex receive information

A

from right visual field

155
Q

where do the optic nerves meet

A

optic chasm

156
Q

where is the optic chasm

A

under the hypothalamus

157
Q

what are the bundles called when they leave the optic chiasm

A

optic tracts

158
Q

what is the first stop for information form the visual pathway

A

lateral geniculate nucleus of the thalamus

159
Q

what is the overlapping areas seen by both eyes called

A

binocular field of vision

160
Q

what is the binocular field of vision important for

A

depth perception

161
Q

what is double vision called

A

diplopia

162
Q

what do blobs process

A

colour

163
Q

what do the ganglion cells that are not used in visual processing do

A

make melanopsin

164
Q

what does melanopsin do

A

light sensitive pigment that plays a key role in setting the body biological clock

165
Q

diagram about aqueous humour

A
166
Q

diagram on nearsightedness etc

A
167
Q

diagram on retinal layers

A
168
Q

diagram of retina through opthalmoscope

A
169
Q

diagram of rods and cones

A
170
Q

diagram on phototransduction

A
171
Q

diagram on visual pathway

A
172
Q

diagram: summary of major eye components

A

ophthalmology (2 decks)

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