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99 Cards in this Set
- Front
- Back
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how does the retina receive its blood supply
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1. choroidal (outer third):
high-flow variable rate 2. retinal (inner 2/3): low flow constant rate higher oxygen content |
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|
RETINAL vessel system:
anastomoses capillary size capillary type tight junction permeability to molecules transport system permeability to fluorescein permeability to indocyanin |
retinal:
1. no anastomoses (end arteries) 2. capillary size: tubular 3. capillary type: continuous 4. TIGHT JUNCTION PRESENT 5. minimal permeability to molecules 6. TRANSPORT SYSTEM PRESENT for essential substrance 7. NOT PERMEABLE TO FLUORESCEIN and INDOCYANIN |
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|
CHOROIDAL vessel system:
anastomoses capillary size capillary type tight junction permeability to molecules transport system permeability to fluorescein permeability to indocyanin |
choroidal:
1. anastomoses at interarterial shunt 2. capillary size: sinusoidal 3. capillary type: fenestrated 4. NO TIGHT JUNCTIONS 5. HIGH permeability to molecules 6. NO transport system 7. HIGH permeability to fluorescein 8. LOW permeability to indocyanin |
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what is the difference between the vasculature in the iris and the ciliary bodies
|
ciliary:
1. capillaries are FENESTRATED in the pars plicata and pars plana 2. capillaries are NOT FENESTRATED in the ciliary muscles 3. blood vessels innervated by small branches of sympathetic fibers iris: 1. tunica intima and tunica media are NOT FENESTRATED 2. blood vessels are not innervated and are not surrounded by smooth muscles 3. contract via pericytes |
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what is the retinal arteries pressure compared to the ophthalmic artery
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retinal arteries 25% LESS than ophthalmic artery
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what is the relationship of the IOP to the episcleral vessels and uveal venous pressure
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1. pressure of episcleral plexus 7.2mmHg below IOP
2. uveal venous pressure is constant if IOP is between 10-15mmHg 3. IOP>15mmHg, the uveal venous pressure is directly proportional to IOP...due to partial collapse of the intrascleral venous plexus |
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what are the two mechanism for blood flow autoregulation
|
1. myogenic: vascular smooth muscle contract in response to stretch and relaxes with a reduction in tension
2. metabolic: local accumulation of vasodilatory metabolites (CO2) and hypoxia result in vasodilation |
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when does clinical papillae occur and where does it mostly occur
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1. when the substantia propria abnormally bulges into the overlying epitherlial layer (cobblestone)
2. most common in upper lid 3. leakage of fluid and acute inflammation |
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does choroidal circulation have autoregulation?
effect on nutrient supply of retina? |
1. NO AUTOREGULATION
2. does not reduce supply of nutrient to the retina, since the extraction of oxygen and glucose INCREASES with DECREASE blood flow |
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what is the difference between follicles and papillae
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Follicles:
1. aggregates of lymphocytes and macrophages 2. clear/fluid filled 3. blood vessel above or below (NEVER WITHIN) 4. eosinphils and basophils NOT found in normal conjunctival epithelium papillae: 1. substantia propia bulges 2. contains eosinphils and basophils 3. blood vessels in center |
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what is the relationship of blood flow between retina and choroid...oxygen consumption, fovea nourishment, glucose supply
|
1. 65% of oxygen consumed by retina is from choroid
2. avascular fovea is nourished by choroid 3. 75% of glucose supply to retina is from choroid 4. high oxygen tension enhances diffusion of oxygen into the retina from the choroid 5. high blood flow in the choroid protects the eye from thermal damage |
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what is clinically relevant from papillae and follicles
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papillae: NOTHING
follicles: viral infections and hypersensitivity |
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what does the visual pigment consist of?
where is the visual pigment located? what is the function of the visual pigment? |
1. visual pigment: chromophore+opsin
2. function: absorb light and convert light energy into electrical activity 3. located in membrane discs of the outer segment |
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what does the absorption spectrum of the visual pigment depend on
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1. nature of chromophore
2. bond between the chromophore and the opsin 3. shape of the protein and quality of the fit 4. orientation of the chromophore in the plasma membrane |
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explain dark current
|
1. with no light, cGMP gated channels are open, causing INFLUX of Na counterbalancing an EFFLUX of K
2. relatively depolarized in dark current (resting potential -40 to -50mV)...average resting potential of a nonretinal neuron is -70mV |
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what does prostaglandins do to the ciliary muscles
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1. relaxation, results in less restricted excellular channels between muscle fibers and increased spacing through which fluid might pass
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what happens in phototransduction
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1. cis-retinal isomerize to trans-retinal (ie. rhodopson to metarhodopsin II)
2. metaRII causes GDP-bound inactive transducin exchange GDP to GTP 3. GTP increase activity of cGMP phosphodiesterase 4. activated cGMP phosphodiesterase hydrolyzes cGMP 5. decreased levels of cGMP causes the closing of cGMP-gated channels which will lead to membrane hyperpolarization |
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what affect does prostaglandins have on trabecular outflow
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1. dose-dependent INCREASE of trabecular outflow
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what are the two types of gains
|
Gain 1. over 100 transducin are activated during the lifetime of a single R*in mammalian rods
Gain 2. PDE* hydrolyze cGMP at a rate close to the limit set by aqueous diffusion combined amplification provided by rhodopsin and PDE are very high, ensuring the high sensitivity of rods, including the ability of rods to detect single photons |
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what is the purpose of guanylate-cyclase (GC)
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restoration of cGMP
1. dark: high Ca2+ conc. promotes GCAP, inhibiting GC 2. light: low Ca2+, allowing GCAP to activate GC...quickly restoring basal cGMP conc. |
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what is the storage form in retinal synthesis
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retinyl palmitate
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what happens to the photoreceptors during light adaptation
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1. initial hyperpolarization
2. followed by secondary, relative depolarization to counteract the initial response to light 3. re-depolarizing influence serves to make the receptor sensitive to further increase in light |
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what are the difference between dermatan sulfate and keratan sulfate
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dermatan sulfate:
1. prefer oxygen-rich environment 2. predominantly in anterior portion 3. more efficient at holding water keratan sulfate: 1. prefer less oxygen 2. posterior portion of cornea 3. absorbs more water, not as efficient as dermatan |
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what efferent CN is used for reflex blink? afferent??
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efferent:
CN VII afferent: CN V (tactile & orbicularis) CN II (light & presence of near objects) CN VIII (auditory) |
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what happens biochemically and neurally during light adaptation
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1. biochem: decreased Ca2+ levels triggers synthesis of cGMP, thereby opening up some of the channels
2. neural: hyperpolarization of the horizontal cells feedback onto the photoreceptors, signaling them to re-depolarize |
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what is the relationship between cones and rods during dark adaptation
|
0-8min: cones reach basal threshold intensity faster than rods.
8-30min: rods then take over after cones have reached basal threshold. rods are more efficient in low luminance than cones...duh!! |
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where are the damaged done when a patient has glaucoma
|
1. sclera lamina of the optic nerve head
2. inner retina: RGC and astroglial population |
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what is the effect of gaze positions on blink rate
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down gaze: 10/min
straight gaze: 15.5/min up gaze: 23/min |
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what is bell phenomenon
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the upward rotation of the globe during the eye closure.
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what is the basal tears secretion rate?
turnover rate? |
1. basal tears secretion: 1.2 microliters/min
2. 10mL in volume over 24hrs 3. turnover rate: 16% of the total volume/min |
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what does the absorption spectrum of the visual pigment depend on
|
1. nature of chromophore
2. bond between the chromophore and the opsin 3. shape of the protein and quality of the fit 4. orientation of the chromophore in the plasma membrane |
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what is the swelling pressure of the normal corneal stroma
|
40-60mmHg
1. it is easy to squeeze water out of a more hydrated stroma and so a low swelling pressure will be recorded IMAGE A SPUNGE |
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|
explain dark current
|
1. with no light, cGMP gated channels are open, causing INFLUX of Na counterbalancing an EFFLUX of K
2. relatively depolarized in dark current (resting potential -40 to -50mV)...average resting potential of a nonretinal neuron is -70mV |
|
|
what happens in phototransduction
|
1. cis-retinal isomerize to trans-retinal (ie. rhodopson to metarhodopsin II)
2. metaRII causes GDP-bound inactive transducin exchange GDP to GTP 3. GTP increase activity of cGMP phosphodiesterase 4. activated cGMP phosphodiesterase hydrolyzes cGMP 5. decreased levels of cGMP causes the closing of cGMP-gated channels which will lead to membrane hyperpolarization |
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|
what are the two types of gains
|
Gain 1. over 100 transducin are activated during the lifetime of a single R*in mammalian rods
Gain 2. PDE* hydrolyze cGMP at a rate close to the limit set by aqueous diffusion combined amplification provided by rhodopsin and PDE are very high, ensuring the high sensitivity of rods, including the ability of rods to detect single photons |
|
|
what is the purpose of guanylate-cyclase (GC)
|
restoration of cGMP
1. dark: high Ca2+ conc. promotes GCAP, inhibiting GC 2. light: low Ca2+, allowing GCAP to activate GC...quickly restoring basal cGMP conc. |
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what is the storage form in retinal synthesis
|
retinyl palmitate
|
|
|
what happens to the photoreceptors during light adaptation
|
1. initial hyperpolarization
2. followed by secondary, relative depolarization to counteract the initial response to light 3. re-depolarizing influence serves to make the receptor sensitive to further increase in light |
|
|
what happens biochemically and neurally during light adaptation
|
1. biochem: decreased Ca2+ levels triggers synthesis of cGMP, thereby opening up some of the channels
2. neural: hyperpolarization of the horizontal cells feedback onto the photoreceptors, signaling them to re-depolarize |
|
|
what is the relationship between cones and rods during dark adaptation
|
0-8min: cones reach basal threshold intensity faster than rods.
8-30min: rods then take over after cones have reached basal threshold. rods are more efficient in low luminance than cones...duh!! |
|
|
where are the damaged done when a patient has glaucoma
|
1. sclera lamina of the optic nerve head
2. inner retina: RGC and astroglial population |
|
|
how does the retina receive its blood supply
|
1. choroidal (outer third):
high-flow variable rate 2. retinal (inner 2/3): low flow constant rate higher oxygen content |
|
|
RETINAL vessel system:
anastomoses capillary size capillary type tight junction permeability to molecules transport system permeability to fluorescein permeability to indocyanin |
retinal:
1. no anastomoses (end arteries) 2. capillary size: tubular 3. capillary type: continuous 4. TIGHT JUNCTION PRESENT 5. minimal permeability to molecules 6. TRANSPORT SYSTEM PRESENT for essential substrance 7. NOT PERMEABLE TO FLUORESCEIN and INDOCYANIN |
|
|
CHOROIDAL vessel system:
anastomoses capillary size capillary type tight junction permeability to molecules transport system permeability to fluorescein permeability to indocyanin |
choroidal:
1. anastomoses at interarterial shunt 2. capillary size: sinusoidal 3. capillary type: fenestrated 4. NO TIGHT JUNCTIONS 5. HIGH permeability to molecules 6. NO transport system 7. HIGH permeability to fluorescein 8. LOW permeability to indocyanin |
|
|
what is the difference between the vasculature in the iris and the ciliary bodies
|
ciliary:
1. capillaries are FENESTRATED in the pars plicata and pars plana 2. capillaries are NOT FENESTRATED in the ciliary muscles 3. blood vessels innervated by small branches of sympathetic fibers iris: 1. tunica intima and tunica media are NOT FENESTRATED 2. blood vessels are not innervated and are not surrounded by smooth muscles 3. contract via pericytes |
|
|
what is the retinal arteries pressure compared to the ophthalmic artery
|
retinal arteries 25% LESS than ophthalmic artery
|
|
|
what is the relationship of the IOP to the episcleral vessels and uveal venous pressure
|
1. pressure of episcleral plexus 7.2mmHg below IOP
2. uveal venous pressure is constant if IOP is between 10-15mmHg 3. IOP>15mmHg, the uveal venous pressure is directly proportional to IOP...due to partial collapse of the intrascleral venous plexus |
|
|
what are the two mechanism for blood flow autoregulation
|
1. myogenic: vascular smooth muscle contract in response to stretch and relaxes with a reduction in tension
2. metabolic: local accumulation of vasodilatory metabolites (CO2) and hypoxia result in vasodilation |
|
|
does choroidal circulation have autoregulation?
effect on nutrient supply of retina? |
1. NO AUTOREGULATION
2. does not reduce supply of nutrient to the retina, since the extraction of oxygen and glucose INCREASES with DECREASE blood flow |
|
|
what is the relationship of blood flow between retina and choroid...oxygen consumption, fovea nourishment, glucose supply
|
1. 65% of oxygen consumed by retina is from choroid
2. avascular fovea is nourished by choroid 3. 75% of glucose supply to retina is from choroid 4. high oxygen tension enhances diffusion of oxygen into the retina from the choroid 5. high blood flow in the choroid protects the eye from thermal damage |
|
|
what does the visual pigment consist of?
where is the visual pigment located? what is the function of the visual pigment? |
1. visual pigment: chromophore+opsin
2. function: absorb light and convert light energy into electrical activity 3. located in membrane discs of the outer segment |
|
|
how does the retina receive its blood supply
|
1. choroidal (outer third):
high-flow variable rate 2. retinal (inner 2/3): low flow constant rate higher oxygen content |
|
|
RETINAL vessel system:
anastomoses capillary size capillary type tight junction permeability to molecules transport system permeability to fluorescein permeability to indocyanin |
retinal:
1. no anastomoses (end arteries) 2. capillary size: tubular 3. capillary type: continuous 4. TIGHT JUNCTION PRESENT 5. minimal permeability to molecules 6. TRANSPORT SYSTEM PRESENT for essential substrance 7. NOT PERMEABLE TO FLUORESCEIN and INDOCYANIN |
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what type of mucin is expressed by all of the epithelia of the ocular surface system
|
MUC1 mRNA
|
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what are the functions of the vitreous
|
1. oxygen tension lowest in the central region
2. metabolic respiratory of wastes and short term retinal needs 3. movement of solute and solvent within eye 4. 50% of the water is turned over in 10-15 minutes 5. must maintain barrier to cell invasion to maintain transparency 6. shock absorber |
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|
CHOROIDAL vessel system:
anastomoses capillary size capillary type tight junction permeability to molecules transport system permeability to fluorescein permeability to indocyanin |
choroidal:
1. anastomoses at interarterial shunt 2. capillary size: sinusoidal 3. capillary type: fenestrated 4. NO TIGHT JUNCTIONS 5. HIGH permeability to molecules 6. NO transport system 7. HIGH permeability to fluorescein 8. LOW permeability to indocyanin |
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what type of mucin is most prevalent in the conjunctival epithelium
|
MUC4
diminished amount in the cornea |
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what is the difference between the vasculature in the iris and the ciliary bodies
|
ciliary:
1. capillaries are FENESTRATED in the pars plicata and pars plana 2. capillaries are NOT FENESTRATED in the ciliary muscles 3. blood vessels innervated by small branches of sympathetic fibers iris: 1. tunica intima and tunica media are NOT FENESTRATED 2. blood vessels are not innervated and are not surrounded by smooth muscles 3. contract via pericytes |
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what type of mucin is most prominent in the tears
|
MUC16
|
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what is the retinal arteries pressure compared to the ophthalmic artery
|
retinal arteries 25% LESS than ophthalmic artery
|
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what is the main function of membrane mucin
|
prevent adhesion of cells and pathogens
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what is the relationship of the IOP to the episcleral vessels and uveal venous pressure
|
1. pressure of episcleral plexus 7.2mmHg below IOP
2. uveal venous pressure is constant if IOP is between 10-15mmHg 3. IOP>15mmHg, the uveal venous pressure is directly proportional to IOP...due to partial collapse of the intrascleral venous plexus |
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how does the eye prevent pathogens from invading
|
1. MAC 1, 4, 16 creates a barrier around the conjunctival epithelium
2. MUC5AC is secreted into the tear film and binds to the foreign body and is removed by the lids |
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what are the two mechanism for blood flow autoregulation
|
1. myogenic: vascular smooth muscle contract in response to stretch and relaxes with a reduction in tension
2. metabolic: local accumulation of vasodilatory metabolites (CO2) and hypoxia result in vasodilation |
|
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what is the backbone of the mucous layer? what is it secreted by?
|
1. MUC5AC
2. secreted by goblet cells also MUC2 but in much lower concentrations |
|
|
does choroidal circulation have autoregulation?
effect on nutrient supply of retina? |
1. NO AUTOREGULATION
2. does not reduce supply of nutrient to the retina, since the extraction of oxygen and glucose INCREASES with DECREASE blood flow |
|
|
what is the relationship of blood flow between retina and choroid...oxygen consumption, fovea nourishment, glucose supply
|
1. 65% of oxygen consumed by retina is from choroid
2. avascular fovea is nourished by choroid 3. 75% of glucose supply to retina is from choroid 4. high oxygen tension enhances diffusion of oxygen into the retina from the choroid 5. high blood flow in the choroid protects the eye from thermal damage |
|
|
what does the visual pigment consist of?
where is the visual pigment located? what is the function of the visual pigment? |
1. visual pigment: chromophore+opsin
2. function: absorb light and convert light energy into electrical activity 3. located in membrane discs of the outer segment |
|
|
what does the absorption spectrum of the visual pigment depend on
|
1. nature of chromophore
2. bond between the chromophore and the opsin 3. shape of the protein and quality of the fit 4. orientation of the chromophore in the plasma membrane |
|
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what are the predominant serum proteins and when are they found in tears
|
1. albumin (most abundant)
2. transferrin 3. IgG (used against blood-borne diseases) found in low concentration in tears...highest levels in nonstimulated tears |
|
|
explain dark current
|
1. with no light, cGMP gated channels are open, causing INFLUX of Na counterbalancing an EFFLUX of K
2. relatively depolarized in dark current (resting potential -40 to -50mV)...average resting potential of a nonretinal neuron is -70mV |
|
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what is the largest immunoglobulin found in tears...what does it do
|
1. IgM
2. active in the early immune response, enhances phagocytosis, and fixes complement |
|
|
what happens in phototransduction
|
1. cis-retinal isomerize to trans-retinal (ie. rhodopson to metarhodopsin II)
2. metaRII causes GDP-bound inactive transducin exchange GDP to GTP 3. GTP increase activity of cGMP phosphodiesterase 4. activated cGMP phosphodiesterase hydrolyzes cGMP 5. decreased levels of cGMP causes the closing of cGMP-gated channels which will lead to membrane hyperpolarization |
|
|
what immunoglobulin is the most numerous in the tears
|
secretory IgA
|
|
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what are the two types of gains
|
Gain 1. over 100 transducin are activated during the lifetime of a single R*in mammalian rods
Gain 2. PDE* hydrolyze cGMP at a rate close to the limit set by aqueous diffusion combined amplification provided by rhodopsin and PDE are very high, ensuring the high sensitivity of rods, including the ability of rods to detect single photons |
|
|
explain the structure of IgA:
MW? what does it consist of? |
1. 385K
2. two chains of plasma IgA connected by a secretory component |
|
|
what is the purpose of guanylate-cyclase (GC)
|
restoration of cGMP
1. dark: high Ca2+ conc. promotes GCAP, inhibiting GC 2. light: low Ca2+, allowing GCAP to activate GC...quickly restoring basal cGMP conc. |
|
|
where is the secretory component in IgA produced
|
1. CONJUNCTIVAL epithelium BUT NOT in CORNEAL epithelium
2. protects from proteolytic and enzymatic digestion |
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what is the storage form in retinal synthesis
|
retinyl palmitate
|
|
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which immunoglobulin has the shortest half life
|
1. IgD
2. 3-5 days 3. least likely to be detected in the tear film of a health individual |
|
|
what happens to the photoreceptors during light adaptation
|
1. initial hyperpolarization
2. followed by secondary, relative depolarization to counteract the initial response to light 3. re-depolarizing influence serves to make the receptor sensitive to further increase in light |
|
|
what happens biochemically and neurally during light adaptation
|
1. biochem: decreased Ca2+ levels triggers synthesis of cGMP, thereby opening up some of the channels
2. neural: hyperpolarization of the horizontal cells feedback onto the photoreceptors, signaling them to re-depolarize |
|
|
what is the purpose of the JONES I test? what dye?
|
1. assess blockages in the lacrimal system
2. fluorescein 45 and younger: 91% passage in 6min 45+: 84% passage in 12min |
|
|
what is the relationship between cones and rods during dark adaptation
|
0-8min: cones reach basal threshold intensity faster than rods.
8-30min: rods then take over after cones have reached basal threshold. rods are more efficient in low luminance than cones...duh!! |
|
|
what is the purpose of the JONES II test? what is used
|
1. after Jones I, punctum is dilated and clear saline is instilled
2. syringe is used to recovery whatever is in the lacrimal sac. recovery: present of dye: normal only saline: obstruction |
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where are the damaged done when a patient has glaucoma
|
1. sclera lamina of the optic nerve head
2. inner retina: RGC and astroglial population |
|
|
what will be the appearance of the cornea with a high amount of GAGs
|
thick and hazy
|
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how will the cornea look under hypoxic conditions
|
cloudy and edematous
|
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where will water flow with a high imimbation rate
|
into the cornea
|
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what type of collagen is prevalent in the cornea with tissue repair
|
type III
|
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|
active secretion is NOT pressure dependent
|
TRUE
|
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|
turnover rate of aqueous humor
|
2hrs
|
|
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level of ascorbate and proteins in the aqueous humor??
|
high ascorbate
low protein |
|
|
the canal of schlemm is drained primarily by external collector channels that leads into the..
|
deep scleral venous plexus
|
|
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what are the major and minor routes of aqueous flow
|
major: trabecular
minor: uvealscleral |
|
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what does the purpose of the cytoskeleton in the aqueous flow
|
1. cell contractility and maintaining cell shape
2. disrupt of cytoskeleton will increase trabecular flow |
|
|
pump leak...where is Na and K concentration highest
|
Na: posterior
K: anterior |
|
|
why is the mackay-marg tonometer accurate with iop of scarred/edematous corneas?
|
1. iop reading is independent of corneal elasticity
2. end point record electronically |
|
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which pathway produces reactants for nucleic acid synthesis
|
1. hexose monophosphate shunt
2. it generates pentose *also produce NADPH for GSH maintenance |
