lacrimal

Question 1

3 componenet of lacrimal system

Answer 1

secretorysystem
distribution system
eliminatio system

Question 2

what secrete tear

Answer 2

lacrimal gland (90%)

accessory lacrimal gland (10%)
-gland of krause ->fornix
-gland of wolfring ->orbital margin of tarsal plate

Question 3

two lacrimal gland

Answer 3

orbital and palpebral lobe

Question 4

describe inside of lacrimal gland

Answer 4

• many lobules separaetd by connective tissure
  -lobule consist of acini
  -inside acini there is secretory cell surrounding central lumen
  -central lumen merge to form intra-lobular duct -> interlobular duct
  -open to superior temporal fornix
  -have myoepithelial cells and lymphocytes

Question 5

innervation of lacrimal (overview)

Answer 5

autonomic pathway
-parasym
-sym

sensory pathway
-lacrimal nerve (ophthalmic branch of trigeminal nerve)

Question 6

describe parasym pathway of lacrimla gland, activate what?

Answer 6

activate tear production

brain stem -> lacrimal nucleus of “facial nerve” -> synapse pterygopalatine ganglion -> maxillary nerve -> zygomatic nerve -> lacrimal nerve -> secretory cell of lacrimal glnad

Question 7

what happen after lacrimal nerve synapse to lacrimal gland (parasym)

Answer 7

1. activation of parasym receptor on secretory cell on lacrimal gland
2. activation of G protein
3. activate enzyme
4. secretory granules bind to cell memebrane -> secrete protein to lumen
   AND
5. ION channels open -> water +ion to lumen

Question 8

what sym input control in lacrimal system

Answer 8

lacrimal vasculature

Question 9

what sensory input do in lacrimal system

Answer 9

be afferent pathway
reflex to stimuli e.g. light -> ophthalmic branch of trigeminal nerve

Question 10

blood supply of lacrimal gland - artery

Answer 10

branch of ophthalmic artery

Question 11

blood supply of lacrimal gland - vein

Answer 11

small, variable

Question 12

explain movement of tear

Answer 12

upper temporal fornix -> move down by gravity -> zipper action of blinking spread tear and move tear nasally -> tear move through tear prism -> contraction of OO shoeten canaliculi and expnad lacrimal sac

Question 13

tear eliminaition system (overview)

Answer 13

naso-lascrimal drainage (75%)

remaining
-evporation
-absorption of conjunctival vessels

Question 14

what are two structure that lacrimal sac sit in between

Answer 14

horner’s muscle (lacrimal)
mediall palpebral ligament

Question 15

what is the name and function of the valve in nasolacrimal duct

Answer 15

Hasner - stop reflux of tear

Question 16

what problem can happen with nasolacrimal duct

Answer 16

nasolacrimal obstruction

Question 17

explain tear drainage

Answer 17

1. prior to blink - fully open
2. during closing phase - puntum meet, canaliculi and sac is compressed, fluid mve to duct
3. reopening - canaliculi and sac expand , negative pressure in sac
4. blink end - punta reopen, fluid flow into puncta and canaliculi

Question 18

role of tear * (5)

Answer 18

(5)
-osmotic boundary = maintain corneal hydration
-gas exhange, nutrient, waste
-optical boundary?
-lubricant
-protection = antimicrobial component + flush

Question 19

what influence tear film stability

Answer 19

-temp
-humidity
-gland output
-blink rate

Question 20

type of tear secretion and example

Answer 20

basic = no EXTERNAL stimuli
reflex = external stimuli e.g. irritation, emotion

Question 21

component of tear

Answer 21

mucin aqueous lipid

Question 22

mucin function*

Answer 22

-maintain hydration and lubrication of cornea and conjunctiva
-prevent microbes from penetrating ocular surface

Question 23

what secrete mucin*

Answer 23

goblet cells
-a lot nasally and fornix
crypts of henle
-present in 1/3 of upper tarsal conjuctiva

Question 24

aqueous function*

Answer 24

-make up bulk of tear film
-maintain pH and osmolarity
-provide oxygen, nutrient, waste
-anitibacteria

Question 25

what secrete aqueous*

Answer 25

-lacrimal galnd
-accessory lacrimal gland = Krause and Wolfring

Question 26

lipid function in tear film*

Answer 26

-reduce evaporation
-prevent overflow of tear
-maintain smooth optical surface
-prevent contamination of tear film by lipid

Question 27

what secrete lipid*

Answer 27

-meibomian gland
-gland of zeis
-gland of moll

Question 28

reflex vs basic tear production*

Answer 28

-100x more in relfex
-basic = aqueous, lipid, mucin
-reflex=only aqueous

Question 29

structure of tear film and components

Answer 29

-superficial lipid layer = outer(non-polar and hydrophobic), inner (polar and hydrophillic)

-aqueous = water, protein and elctrolytes
-mucin = aqueous with more mucin
-glyocalyx = layer attache epithelail cell

Question 30

what is glycocalyx and function

Answer 30

-glycoprotein layer secreted by epithelium

hydrate epithelial cell + bond epithelium to mucin layer

Question 31

tear film thickness

Answer 31

2-5 micron

Question 32

how tear different in many age

Answer 32

-87% new born = relfex tearing at birth
-95%=show reflex tearing within one week
-tear film stability is high in new born, low in old age

Question 33

types of tear enzyme and enefits

Answer 33

lactate and malate
-use for fertmine physiological change
-ratio = determine hypoxic stress

Question 34

what determine glucose level in tear

Answer 34

blood glucose level

Question 35

what is the importance of tear osmolality
what happen if it’s too high or low

Answer 35

-maintain epithelial integrity and corneal hydration
-too high = fluid drawn out of cornea

Question 36

what can affect osmolality of tear

Answer 36

-less osm = prolonged eye closure because reduced tear evaporation (น้ำมาก)
-more osm = dry eye because more tear evaporation

Question 37

why pH of tear is lowest after waking up

Answer 37

acidic by-product of corneal anaerobic metabolism in low O2 environment

Question 38

what is the pH of tear film

Answer 38

7.45

Question 39

what is the volume of tear film

Answer 39

7.0ol

Question 40

rate of production of basic vs reflex tear film

Answer 40

1-2ul/min in basic, >100ul/min in reflex

Question 41

what is Holly and Lemp model

Answer 41

thinning of tear film layer -> lipid and mucin component contaminate-> break up of tear film

Question 42

what is Sharma and Ruckenstein model

Answer 42

dispersive force of mucous layer -> aqueous phase contact epithelial surface -> break up of tear film

Question 43

Mcdonald and Brubaker

Answer 43

meniscus of eye make thining of tear film -> tear film breakup near eye lid margin

Question 44

classification of dry eye

Answer 44

aqueous tear deficiency (not enough aqueous - quantity)
evaporative (evaporate excessively)

Question 45

type of aqueous tear deficiency

Answer 45

sjogren’s syndrome
-auto immune
-dry mouth
-older femal patients
non sjogren
-lacrimal gland disease
-lacrimal duct obstruction
-facial nerve palsy

Question 46

type of evaporative

Answer 46

-lipid deficient (meibomian gland dysfunction*, blepharitis)
-surface change (mucin deficiency = chemical burn)
-lipid anomaly (blinking) = not spreading tear properly

Question 47

evaluation of dry eye *

Answer 47

tear quality
tear quatity
ocular surface

Question 48

example of tear quantity test*

Answer 48

schirmer - piece of paper
<5 mm in min = dry eye
5-10mm = border line
>10mm = normal

phenol thread test

Question 49

example of tear quality test*

Answer 49

fluorescein break-up time
-observe dark spot (timiing)
<10 seconds = dry eye

non-invasive break-up time
-reflection from ocular surface
-discontinuity of reflectio = tear film break up
should be >20 seconds