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68 Cards in this Set
- Front
- Back
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from largest to smallest...arrange the fornix
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superior
inferior temporal medial |
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what prevents the conjunctiva from folding downward over the cornea
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the attachment between the levator palpebral superioris and the conjunctiva
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where and what is the plica semilunaris located
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1. located at the inner canthus
2. a reversed fornix with the fold of conjunctiva lying externally |
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how is the tear film stabilized
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1. arrangements of microvilli and microplicae
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how are the microvilli and microplicae arranged on the conjunctiva
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1. systems of outfolding
2. cell membrane open during secretion and the reorient following 3. support, stabilize, anchor, and prevent irregular streams and flow patterns |
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what effects does venous dilation, tortuosity, formation of fusiform or saccular microaneurysms have on the conjunctival vessels
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ABSOLUTELY FUCKEN NOTHING!!!!
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what is the difference between an irritation/infection of the superficial conjunctiva versus deeper vessels in the conjunctiva
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superficial: vascular pattern increases in prominence moving away from limbus
deep: vascular pattern increasing towards the limbus |
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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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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 clinically relevant from papillae and follicles
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papillae: NOTHING
follicles: viral infections and hypersensitivity |
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top 3 causes for bacterial infection
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1. staphylococcus albus
2. diphtheroids 3. staphylococcus aureus |
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top 3 causes for fungal infection
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1. aspergillus
2. candida 3. harmodendem |
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what neurotransmitters do the parasympathetics nerves use to trigger goblet cell secretion
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1. acetylcholine (Ach)
2. vasoactive intestinal peptide (VIP) |
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what is the driving force for conjunctival fluid secretion and where is it located
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1. Na-K-ATPase (extrudes 3Na, influx 2K)
2. basolateral side of the conjunctival epithelium (serum side) |
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what are the three types of blinks
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1. voluntary
2. reflex 3. spontaneous |
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which type of blinking requires the highest potential amplitude to initiate (EMG)
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VOLUNTARY BLINKS
uses orbital portion of the orbicularis oculi |
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which blink is induced by a stimulus.
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REFLEX
contraction of pretarsal orbicularis |
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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 is the main purpose of spontaneous blinking
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1. reform and redistribute precorneal tear film
2. smallest EMG amplitude 3. no retinal stimulation required |
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which phase is faster in spontaneous blinking? total blink time?
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down phase is twice as fast as up phase
total blink time: ~260msec |
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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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average blink rate? what is the effect on blink rate with reading or conversation?
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average: 15-17/min
reading: 4.5/min conversation: 26/min on average men blink less than women |
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what is the effect of contact lens on blink rate?
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increase in blink rate
rigid: 23/min soft: 20/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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where can mast cells be found in the conjunctiva
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conjunctival stroma in the adenoid layer (superficial)
normally none in the conjunctival epithelium, unless disease is the case |
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what is the relationship between molecular weight of a compound and the permeability through the sclera
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INVERSE
HIGH MW=LOW PERMEABILITY visa versa |
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what is the main route for drug entry to the vitreous
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transscleral diffusion
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what reaction order is observed for hydrophilic drug diffusion across the sclera
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FIRST ORDER KINETICS
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read about scleral rigidity
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NOW!!!
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Basal Secretion of Lacrimal Sys.
1. stimulus 2. afferent 3. control system 4. efferent 5. main source |
1. stimulus: NONE
2. afferent: NONE 3. control sys: SYMPATHETIC 4. efferent: SCG 5. main source: ACCESSORY LACRIMAL GLANDS |
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Reflex Secretion (Peripheral) of Lacrimal Sys.
1. stimulus 2. afferent 3. control system 4. efferent 5. main source |
1. stimulus: CORNEAL STIMULUS
2. afferent: CN V 3. control sys: PARASYMPATHETIC 4. efferent: SPHENOPALATINE GANGLION 5. main source: LACRIMAL GLAND |
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Reflex Secretion (CENTRAL) of Lacrimal Sys.
1. stimulus 2. afferent 3. control system 4. efferent 5. main source |
1. stimulus: LIGHT
2. afferent: CORTICAL 3. control sys: PARASYMPATHETIC 4. efferent: SPHENOPALATINE GANGLION 5. main source: LACRIMAL GLAND |
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requirement for proper distribution and wetting of tears
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1. quantity and composition of mucin
2. quantity and composition of lipid 3. sufficient blink frequency 4. good lid-cornea apposition 5. adequate fluid volume |
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what is the mechanism of lacrimal drainage
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1. 1/3 closed: puncta occluded by contact of lid margins
2. 2/3 closed: further lid closure squeeze canaliculi and sac 3. closed: canaliculi now nearly empty, partial vacuum formed as lids open 4. 1/3 open: release of pressure on canaliculi, puncta still occluded 5. 2/3 open: puncta open, tears enter 6. open: ready for blink |
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tear volume that the conjunctival surface can hold before it overflows
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conjunctival surface cannot support a volume of more than 25 microliters if this vol. is added quickly
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what is the maximum capacity of the lacrimal sac
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~30 microliters
vol greater than this expands the sac, compressing the plexus of veins that surrounds it |
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total tear film for an adult?
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average 7 microliters
range 4-13 microliters |
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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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how much tears is present on the eyes to give it a watery appearance without overflow
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10 microliters added quickly
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Basal Secretion of Lacrimal Sys.
1. stimulus 2. afferent 3. control system 4. efferent 5. main source |
1. stimulus: NONE
2. afferent: NONE 3. control sys: SYMPATHETIC 4. efferent: SCG 5. main source: ACCESSORY LACRIMAL GLANDS |
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Reflex Secretion (Peripheral) of Lacrimal Sys.
1. stimulus 2. afferent 3. control system 4. efferent 5. main source |
1. stimulus: CORNEAL STIMULUS
2. afferent: CN V 3. control sys: PARASYMPATHETIC 4. efferent: SPHENOPALATINE GANGLION 5. main source: LACRIMAL GLAND |
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Reflex Secretion (CENTRAL) of Lacrimal Sys.
1. stimulus 2. afferent 3. control sys 4. efferent 5. main source |
1. stimulus: LIGHT
2. afferent: CORTICAL 3. control sys: PARASYMPATHETIC 4. efferent: SPHENOPALATINE GANGLION 5. main source: LACRIMAL GLAND |
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requirement for proper distribution and wetting of tears
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1. quantity and composition of mucin
2. adequate fluid volume 3. sufficient blink frequency 4. good lid-cornea apposition 5. quantity and composition of lipid |
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what is the mechanism of lacrimal drainage
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1. 1/3 closed: puncta occluded by contact of lid margins
2. 2/3 closed: further lid closure squeeze canaliculi and sac 3. closed: canaliculi now nearly empty, partial vacuum formed as lids open 4. 1/3 open: release of pressure on canaliculi, puncta still occluded 5. 2/3 open: puncta open, tears enter 6. open: ready for blink |
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tear volume that the conjunctival surface can hold before it overflows
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conjunctival surface cannot support a volume of more than 25 microliters if this vol. is added quickly
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what is the maximum capacity of the lacrimal sac
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~30 microliters
vol greater than this expands the sac, compressing the plexus of veins that surrounds it |
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total tear film for an adult?
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average 7 microliters
range 4-13 microliters |
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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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how much tears is present on the eyes to give it a watery appearance without overflow
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10 microliters added quickly
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what type of mucin is expressed by all of the epithelia of the ocular surface system
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MUC1 mRNA
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what type of mucin is most prevalent in the conjunctival epithelium
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MUC4
diminished amount in the cornea |
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what type of mucin is most prominent in the tears
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MUC16
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what is the main function of membrane mucin
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prevent adhesion of cells and pathogens
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how does the eye prevent pathogens from invading
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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 is the backbone of the mucous layer? what is it secreted by?
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1. MUC5AC
2. secreted by goblet cells also MUC2 but in much lower concentrations |
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what is the purpose of the lipid layer in the tear film
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reduces evaporation
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what happens to the NaCl levels in the tear film with the eyes open or closed
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closed: 0.9% NaCl
open: 1.0% NaCl or greater the slight hypertonicity pulls fluid from the aqueous humor into the tear film cornea thins (2-3%) when the lids are held open |
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what types of junctions form the blood-tear barrier? how do serum proteins enter the tears?
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1. apical tight junctions (zonular occludens)
2. conjunctival surface capillaries |
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what are the predominant serum proteins and when are they found in tears
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1. albumin (most abundant)
2. transferrin 3. IgG (used against blood-borne diseases) found in low concentration in tears...highest levels in nonstimulated tears |
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what is the largest immunoglobulin found in tears...what does it do
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1. IgM
2. active in the early immune response, enhances phagocytosis, and fixes complement |
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what immunoglobulin is the most numerous in the tears
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secretory IgA
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explain the structure of IgA:
MW? what does it consist of? |
1. 385K
2. two chains of plasma IgA connected by a secretory component |
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where is the secretory component in IgA produced
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1. CONJUNCTIVAL epithelium BUT NOT in CORNEAL epithelium
2. protects from proteolytic and enzymatic digestion |
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which immunoglobulin has the shortest half life
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1. IgD
2. 3-5 days 3. least likely to be detected in the tear film of a health individual |
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what is the purpose of the complement system
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1. complex network of proteins, enzymes and inhibitors
2. protect the external eye against infection or participating in the inflammatory action |
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what is the purpose of the JONES I test? what dye?
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1. assess blockages in the lacrimal system
2. fluorescein 45 and younger: 91% passage in 6min 45+: 84% passage in 12min |
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what is the purpose of the JONES II test? what is used
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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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what do the results of the schirmer test reveal?
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less than 10mm: hyposecretion
10-30: normal-pseudo epiphora |
