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NBEO Part 1 > Ocular Physiology > Flashcards

Ocular Physiology Flashcards

1
Q

What type of blinking is most common?

A

Spontaneous.

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2
Q

How many blinks is normal per minute?

A

12-15

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3
Q

What part of lid does spontaneous blinking?

A

palpebral

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4
Q

Reflex blinking nerves

A

CN II dazzle and menis. CN V-irritation CN VIII-loud noises.

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5
Q

What part of eye does reflex blinks?

A

palpebral

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6
Q

Which is the only reflex that does not involve the cortex?

A

Dazzle. All other begin in the frontal lobe.

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7
Q

What causes voluntary blinking

A

palpebral and orbital.

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8
Q

Benign essential belpharospasms

A

Contractions of orbiculares oculi, procures, and corrugated.

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9
Q

Bell’s phenomenon

A

Upward and out eye with forced closure

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10
Q

Which glands can increase secretion with blinking?

A

Meiobomian

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11
Q

What do accessory lacrimal glands do?

A

Basal or maintenance tears

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12
Q

What does the main lacrimal gland do?

A

Reflex or emotional tearing

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13
Q

Which glands help with lipid layers?

A

Meiobomian, Zeiss, Moll.

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14
Q

Horners

A

Contractions on closure and shortens the cannaliculi

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15
Q

How does blinking help tear film

A

Goes from lateral to medial

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16
Q

How many eyelashes do we have

A

150 on top and 75 on bottom

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17
Q

What is lipid layer made of

A

fatty acids, cholesterol, waxy esters.

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18
Q

How do tears change with age?

A

Decrease in lysozyme and lactoferrin and decreased aqueous protection

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19
Q

What does contact lens wear do?

A

Increases electrolyte and protein concentration due to tear evaportion

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20
Q

How do tears change under closed eye conditions

A

Increases IA and serum albumin

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21
Q

How are mucin layer unique

A

Capable of mixing with lipid and water.

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22
Q

Where are goblet cells found?

A

Inferonasal fornix and bulbar conj (most temporal)

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23
Q

What do goblet cells need for development

A

Vitamin A

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24
Q

Bitot’s spots

A

foamy build up of keratin on the cornea. Caused by vitamin A deficiency.

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25
Q

Lipid soluble vitmins

A

DEAK

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26
Q

Antioxidants

A

ACE

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27
Q

Water soluble vitamins

A

B and C

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28
Q

What is TBUT evaluating

A

The tear film evaporation due to an inefficient lipid layer

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29
Q

What does the mucin layer interact with

A

glycocalyx of the epithelium.

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30
Q

Normal tear production per minuts

A

1 ul/min.

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31
Q

Normal tear film osmolarity

A

308

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32
Q

Main ions to osmolarity

A

Na and K

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33
Q

How does DES affect tear osmolarity

A

Increase is osmolarity

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34
Q

What kind of drops would you use with DES

A

hypotonic. More water.

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35
Q

Potassium concentration in tears

A

Very high! helps to maintain health of corneal epithelium.

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36
Q

Average pH of tears

A

7.45

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37
Q

pH of tears when sleeping

A

decreases

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38
Q

pH of tears with DES

A

increases due to increased osmolarity

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39
Q

What are most ophthalmic drugs

A

weak bases.

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40
Q

Stapedius muscles

A

Dampen sound. Innervated by CN VII

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41
Q

Vestibule

A

Linear VOR. Movements of head or body from side to side.

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42
Q

Semi-circular canals

A

Angular VOR. Rotation movements of the body or head.

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43
Q

Saccades

A

contralateral and FEF and SC. EX: Right FEF controls saccades to the left

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44
Q

Pursuits

A

ipsilateral parietal lobe. Right pursuit driven by right parental lobe.

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45
Q

VOR

A

Your body is moving!

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46
Q

How are the layers of the cornea in response to water

A

Epithelium: lipophilic, stroma: hydrophobic, endo: lipophilic.

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47
Q

UV c

A

200-290

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48
Q

UV B

A

290-320

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49
Q

UV A

A

320-400

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50
Q

What absorbs from 200-300

A

Cornea (epi and bowman).

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51
Q

What absorbs from 300-400

A

Lens

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52
Q

What absorbs from 300-350

A

vitreous

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53
Q

What absorbs above 400

A

retina

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54
Q

What vitamin helps the lens

A

Vitamin C

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55
Q

What does the precise spacing in the lens do?

A

Destructive interferance

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56
Q

Corneal desturgence

A

The relative dehydration of the cornea

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57
Q

Epithelium Pump mechanism

A

Na in and Cl, H20 and K+. Out. Has an Na/K ATPase pumps that puts NA in stroma and NA/K/CL cotransporter Will then pump K in aqueous and CL in epithelium which then leaves with H20.

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58
Q

Endothelium Pump Mechanism

A

Pumps NA in and Cl, water, and bicarbonate out. Use an NA/K ATPase pump.

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59
Q

Major factors in corneal desurgence

A

Na in and Cl, and H20 out. (bicarbonate in endo).

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60
Q

K+ factor in corneal dusurgence

A

The sensor.

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61
Q

Partial pressure of O2 in the eyes with open conditions

A

144 mm HG

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62
Q

How does eye get oxygen during closed eye conditions

A

Palpebral conj, aqueous humor

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63
Q

Critical PPO2 for the cornea

A

10-20 mm HG.

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64
Q

Transmisibility

A

DK/t. How much oxygen will diffuse over a given thickness.

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65
Q

Nutrition for cornea

A

glucose is low in tears but high in aqueous humor. Corneal epithelial cells can also store glycogen for mitosis.

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66
Q

How many days for cornea to regenerate

A

7-14 days.

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67
Q

Steps when trauma to cornea happens

A

Mitosis in basal stops, squamous cells migrate, mitosis increases rapidly.

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68
Q

How long for healing if BM is damaged

A

8 weeks

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69
Q

Why can corticosteroids and tetracyclines be used for RCE

A

MMPs degrade hemidesmosome formation and these drugs stop that from occurring and help formation

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70
Q

Which layers cannot regenerate

A

Bowman’s and endo.

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71
Q

Which layer can regenreate

A

epithelium and descents.

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72
Q

Does the anterior or posterior lens change more in curvature with accommodation?

A

The anterior

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73
Q

What structure has the most protein in the body?

A

The lens.

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74
Q

How does the lens maintain it’s water balance

A

Na/K ATPase pump. Na leaves and water follows.

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75
Q

Resurgence in Epithelium vs. lens

A

Epithelium pumps NA in and Cl and H20 out. Lens pumps Na out.

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76
Q

How does lens get energy?

A

Anerobic metabolism. Has lots of hexokinase.

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77
Q

What happens with diabetic cataract?

A

Excess sorbitol in the lens.

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78
Q

Glutathione

A

Good for the lens.

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79
Q

Absobic Acid

A

Vitamin C. Also protects from damage.

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80
Q

What layer of lens can do aerobic respiration

A

epithelium.

81
Q

Why is there a large amount of lactate in the lens?

A

Large amount of anerobic metabolism

82
Q

Which part of the lens has the sutures?

A

Fetal

83
Q

Which part of the lens needs the greatest energy and nutrients?

A

Anterior epithelium (why it is good that it can do aerobic respiration)

84
Q

What type of collagen is in the lens

A

Type IV.

85
Q

Where is the lens capsule thickest

A

Front

86
Q

What contributes to cataract formation

A

Decreases glutathione, decrease in crystallin factors, and an increase in Ca.

87
Q

Which part of lens has the highest refractive index

A

The embryonic.

88
Q

Aqueous humor secretion and age?

A

Decreases

89
Q

Choroid has a high concentration of protein. Why?

A

To create a gradient that will absorb excess H20 from the retina and into the choroid

90
Q

What type of collagen is the viterous

A

Type 2

91
Q

Gag in the viterous

A

Hyaluronic acid.

92
Q

Vitamin C in the viterous

A

Very high.

93
Q

Metabolic function of the viterous

A

No metabolic function so instead acts as a metabolic buffer and storage area

94
Q

Where in the vitreous is collagen highest

A

Near the base.

95
Q

How does hyaluronic acid change with age

A

increases (liquidifaction)

96
Q

Perfusion pressure

A

Parteries-Pveins

97
Q

What are two factors causing resistance

A

Autonomic and autoregulation

98
Q

what are two things that can autoregulate

A

ON axo flow and retina. Pericytes control this.

99
Q

What does sympathetic cause

A

vasoconstriction

100
Q

what does para cause

A

vasodilation

101
Q

Ocular perfusion pressure

A

Diastolic pressure-IOP.

102
Q

Critical closing pressure

A

The pressure where the blood vessel collapse and blood flow stops.

103
Q

Transmural pressure

A

Pressure across the vessel wall. Pressure outside vs. inside vessel.

104
Q

Does the sympathetic system affect retinal blood flow?

A

NO! DO not innervate the CRA past the lamina cribosa. Do innervate uvea though. If there is a sudden increase in BP then the sympathetic will constrict the uveal blood vessels to decrease flow

105
Q

Parasympathetic system and retinal blood flow?

A

Parasmpathic is most prevalent in uveal tract. Minimal influence on choroidal and retinal blood flow. Causes vasodilation with drop in blood pressure

106
Q

IOP must be ______ that the episcleral venous pressure

A

Greater. Allows outflow

107
Q

IOP must be _____ than the ICP

A

Greater. Allows axoplasmic flow.

108
Q

IOP must be _____ than the retinal and uveal arteries

A

Lower. Allow nutrients to be delivered

109
Q

Which vessels in the uvea are fenestrated

A

MACI and choroidal capillaires

110
Q

Blood supply in the fovea

A

Avascular so supplied by choriocapillaris

111
Q

Blood retinal barrier

A

Blood vessels of retina and RPE

112
Q

How does light absorption change the photopgigment

A

goest from 11-cis-retinal to all-trans-retinal.

113
Q

Recycling of the photopigments

A

11-cis-retinal->all trans retinal–>all trans retinol–>RPE–>11 cis retinol–>11-cis retinal.–>photopigments

114
Q

Dark Current

A

Na coming in and out. Depolarizes the photoreceptor

115
Q

What happens with light

A

CGMP closes the Na channel and hyper polarization occurs and does not produce glutamate.

116
Q

Gaba and Glycine

A

Inhibitory. Amacrine and horizontal.

117
Q

Which cells are off cells

A

photoreceptors, off center bipolar, horizontal. All hyper polarize in response to light. Less glutamate

118
Q

On center bipolar

A

Depolarizes in response to light. Normally inhibited by glutamate.

119
Q

Off center bipolar

A

hyper polarize in response to light. Excited by glutamate so less=hyper polarize

120
Q

Rod bipolar

A

Always ON. Depolarize to light.

121
Q

Horizontal cells

A

Off cells. Hyper polarize to light. No center surround.

122
Q

Amacrine cells

A

On center. Depolarize to light. Have center surround.

123
Q

On center ganglions

A

synapse with on center bipolar and depolarize to light.

124
Q

Off center ganglions

A

synapse with off center bipolar and hyper polarize to light.

125
Q

Action potentials

A

All or nothing response-Amacrine and ganglion are AP. All others are not

126
Q

Graded potentials

A

Determined by amount of photons absorbed. All but ganglion and amacrine.

127
Q

Pyramidal motor pathway

A

complicated voluntary movements.

128
Q

Medulla

A

Where most pathways cross. Above is contralateral. Below is ipsilateral.

129
Q

Reticulospinal

A

Complex voluntary movement

130
Q

Tectospinal

A

Uses the SC

131
Q

Spinalthalamic

A

Hot pain.

132
Q

Trigemothalamic

A

pain and hot from face.

133
Q

Medial lemniscus

A

Touch, pressure, vibration.

134
Q

SNS roles

A

vasodilation in skeleton muscle, dilates the bronchioles, increases blood glucose levels.

135
Q

Preganglionic SNS

A

Release acetycholine

136
Q

Post ganglionic SNS

A

Releases Norepinephrine

137
Q

Which is the only gland innervated by preganlionic SNS

A

Adrenal gland

138
Q

What does PSN release

A

acetylcholine for both

139
Q

When do you use CT

A

bone, calcium, or emergency. Look at ca density.

140
Q

When do you use PET

A

cancers. Looks at glucose uptake

141
Q

When do you use MRI

A

soft tissue, look at mobile protons-more water-diseased tissue.

142
Q

Where is the LGN located?

A

Thalamus.

143
Q

Is LGN simply a rely station?

A

NO! Is is also a center for processing input from multiple sources and deciding what is sent to V1

144
Q

Who does LGN receive input from?

A

Optic tract, SC, V1 (last two are feedback)

145
Q

Which layers of LGN receive mango? Parvo? Konio?

A

Magno=1,2 Parvo=3-6 Konio=inbetween

146
Q

Which layer are ispliateral in LGN

A

2,3,5

147
Q

Which layers are contralateral in LGN

A

1,4,6

148
Q

Where is the first area that binocular processing occurs?

A

V1

149
Q

Medial to lateral in lgn

A

fovea->peripheral vision

150
Q

Anterior to poster in LGN

A

inferior to superioer

151
Q

Dorsal to vental LGN

A

Same spot in the VF

152
Q

Optic radiations of inferior

A

Temporal lobe in meyer’s loop

153
Q

Optic radiation of supeior

A

Parietal lobe.

154
Q

Parvo cells

A

Sensitive to red green, fine details, and slow motion but have a slower transmission speed

155
Q

Magno cells

A

monochromatic and are most sensitive to fast movements and large details.

156
Q

Visual Cortex

A

Striate cortex, boardman 17 or V1.

157
Q

layer 4 of visual cortex

A

receives input from optic radiations. Have ocular dominance columns.

158
Q

Layer 3 of visual cortex

A

Axons to other cortical layers

159
Q

Layer 6 of V1

A

Sends feedback back to LGN

160
Q

Function of V1

A

examine basically features before relaying information to more complex processing centers (v2-v5)

161
Q

Layer 5 and 6 of V1

A

subcortical areas (SC, Thalamus, midbrain, pons)

162
Q

V2-V5

A

Responsible for complex processing. Includes IT (what) and MT (where)

163
Q

SC

A

Receives input from V1 and fibers that exit the optic tract. Controls saccades, visual orientation, and foveation.

164
Q

FEF

A

Only receives information from V1. Does near response and saccades.

165
Q

Simple Cells of the Visual Cortex

A

respond to orientation of stimuli. Have elongated center surround

166
Q

Complex cells of the visual cortex

A

Respond to motion and orientation. NO center surround.

167
Q

Hypercomplex cells

A

Process combined input from multiple cells

168
Q

How does V1 process information

A

heriarchialy.

169
Q

EOG

A

Measures the health of the RPE

170
Q

Arden ratio

A

EOG. The ratio of light peak to dark trough

171
Q

What arden ratio do we want

A

Above 1.80

172
Q

ERG

A

Looks at activity of outer retinal layers. No ganglion cell layers.

173
Q

A wave

A

negative and photorceptors

174
Q

B-wave

A

positive and bipolar and muller

175
Q

C-wave

A

positive and RPE

176
Q

How to isolate rod function on EOG

A

Blue flash with a slow flicker in a dim background

177
Q

How to isolate cone function on EGO

A

Red flash with a fast flicker in a bright background.

178
Q

Pattern ERGs

A

Target the ganglion cels

179
Q

VEP

A

Latency of brain activity to visual stimulus

180
Q

Normal VEP

A

100 sec

181
Q

What always causes anisocoria

A

efferent pathway problem

182
Q

Near response

A

FEF gets input from V1 and synapse with EW (no pretectacl)

183
Q

SNS and EW

A

Sympathetic fibers inhibit the EW from constant parasympathetic features.

184
Q

Goldman measurement

A

Based on elasticity of the cornea. Based on cornea thickness of 520.

185
Q

Thick corneas on goldman

A

Overestimate

186
Q

NCT

A

Time

187
Q

Pascal

A

Contour. Do not take corneal thickness into account

188
Q

Average IOP

A

15

189
Q

How to decrease IOP w/o topical

A

Exercise, drink beer, marijuana.

190
Q

When is IOP highest

A

330-530 AM

191
Q

How often is the total volume of the aqueous replaced

A

every 100 minutes

192
Q

Uveoscleral is Presure _____ while corneal scleral is Pressue _______

A

independent dependent

193
Q

What are two conditions that can increase episcleral venous pressure

A

Spurge-Weber and arteriovenous fistulas.

194
Q

Osmolarity of the aqueous

A

Slightly hyper osmotic to plasma due to bicarbonate.

195
Q

How can aqueous be made? What is the main one?

A

Diffusion, ultrafilteraion, active secretion. Active secretion.

196
Q

Pumps that make aqeuous

A

NA/K atpase pump pumps NA into the posterior chamber. Bicarbonate is also made and causes water and Cl to follow.

197
Q

What can cause covering of the TM

A

Diabetes, CRVOs, Uveitis, hyphema

198
Q

What can cause injury to the TM

A

Fuchs heterochromatic iritis, glaucomatocyclic crisis (trabeculitis that can cause damage), angle recession glaucoma.

199
Q

Occlusion of the TM

A

Pseduoedcofiliative glaucoma or Pigment dispersion glaucoma.

NBEO Part 1 (17 decks)

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