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Anatomy > Lecture 11 > Flashcards

Lecture 11 Flashcards

1
Q

How many tears do we produce per 16 hours of wakefulness? How does tear production change with age?

A

0.5-1.25g

it decreases with age (very common)

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2
Q

What is the pH of tears?

A

7.4 (range 5-8)

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3
Q

What ions make up the salt composition in tears?

A

Na+, K+, Cl- and HCO3-

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4
Q

if there is not alot of tear production, how does this alter the salt concentration?

A

salt oncentration will be higher and cause hypertonic conditions. (at higher tear production rates we see isotonic)

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5
Q

What are the three categories of tear functions?

A

Mechanical, nutritional and immunological

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6
Q

What functions are considered mechanical functions by the tears?

A
  1. optical surface (cornea is not completely smooth surface, has villi and valleys, tear film helps smooth this out and create a smoother surface)
  2. flush foreign materials
  3. lubricant
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7
Q

What functions are considered nutritional functions by the tears?

A
  1. provide oxygen

2. ions (K+, Ca2+ and Mg2+)

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8
Q

What functions are considered immunological functions by the tears?

A
  1. antibacterial/bacteriolytic lyzozymes

2. sIgA protects mucosal surfaces (secretory IgA creates a slippery surface so bacteria cant adhere to the cornea).

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9
Q

What glands are involved in making the aqeous portion of tears?

A
  1. Lacrimal gland (makes largest portion)
  2. Accessory lacrimal glands of krause
  3. accessory lacrimal glands of wolfring
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10
Q

What glands are involved in making the oil portion of the tears?

A
  1. Meibomian glands (produces largest portion of oil layer)
  2. Sebaceous glands of Zeis (connected to eyelashes allows lubrication of lash)
  3. Glands of Moll
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11
Q

What glands are involved in making the mucin portion of the tears?

A
  1. conjunctival goblet cells

2. corneal and conjunctival epithelium (stratified squamous cells).

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12
Q

What divides he lacrimal gland into the two portions (orbital and palpebral)?

A

Aponeurosis: tendonous sheath attaching to the cartilaginous tarsal plate. it is part of the levator muscle.

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13
Q

Where is the lacrimal gland located?

A

in the lacrimal fossa

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14
Q

What type of cells are located outside the lacrimal gland? inside?

A

acinar cells in general. outside= basal myoepithelial and inside is columnar cells.

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15
Q

is the lacrimal gland present at birth?

A

NO develops after birth.

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16
Q

hat does the lacrimal gland mainly secrete?

A

sero-mucous secretion= made up of aqeous, ions, salts and mucin (protein part).

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17
Q

Where is mullers muscle located?

A

under levator, it is smooth muscle and allows for the eyelids to open wide (sympathetic stimulation).

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18
Q

Blocking of which pore can cause a sty to develop?

A

meibomian gland.

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19
Q

Easiest way to get rid of an infection in the gland of zeis?

A

remove hair follicle and open up the duct.

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20
Q

where are meibomian glands located? how many superiorly and inferiorly?

A

embedded in the tarsal pate (30-40 in superior lid, 20-30 in inferior lid).

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21
Q

What do the meibomian glands secrete? How is it released?

A

sebum via holocrine secretion (whole cell bursts), released by mechanical action of blinking.

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22
Q

where is the gland of krause found? what does it secrete? where is gland of wolfring found? what does it secrete?
Where are the Krause glands mostly concentrated?

A

at fornix, sero-mucin secretion (much less than lacrimal gland).
orbital portion of tarsal plate, secretes sero-mucin (much less than lacrimal gland).
20-40 in upper lid and 6-8 in lower lid.

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23
Q

Goblet cells in conjunctiva secrete mucin which allows for?

A

wetting of cornea.

24
Q

corneal and conjunctival epithelia produce mucin through stratified sqamous cells but they are also a minor producer of?

A

aqueous layer.

25
Q

What are the three main tear layers?

A

Oil, aqueous and mucous layer.

26
Q

Which layer of tears is in contact with outside environment?

A

oil layer (very thin layer).

27
Q

What is the middle layer of tears? what is the main function of this layer?

A

aqueous or serous.

provides cornea with oxygen, nutrients, etc.

28
Q

Which tear layer is in contact with the corneal epithelium?

A

mucous layer.

29
Q

Which branch carries sensory information from the lacrimal gland itself? is this efferent or afferent?

A

lacrimal branch of trigem nerve (CNV1), afferent.

30
Q

Which nerve senses corneal sensation or stimulation which can cause tearing? efferent or afferent?

A

long ciliary nerve (CNV1).

afferent

31
Q

pronounced stimulation of other branches of which nerve can also cause tearing? efferent or afferent?

A

trigeminal.

afferent.

32
Q

Does parasympathetic produce or reduce tears? what does sympathetic do?

A

produces.

reduces.

33
Q

Which type of nerves are the ONLY ones present inside acinus of lacrimal gland?

A

parasympathetic.

34
Q

What are the two types of tearing?

A
  1. basal (normal everyday levels)

2. reflex (i.e. crying/scratched cornea)

35
Q

Two ways reflex tearing can be stimulated?

A
  1. peripheral (via CNV): unilateral with weak stimulus (i.e. eyelash) or bilateral with strong stimulus (i.e. scratched cornea).
  2. Central (emotional) ALWAYS bilateral (CANT cry with just one eye ALWAYS TWO).
36
Q

In the classical theory, where does reflex tearing secrete from? basal tearing?

A

lacrimal gland.

accessory glands.

37
Q

In the modern theory, where does reflex tearing secrete from? basal?

A

fast secretion from distinct inducible vesicles in each gland.
slow, ongoing secretion from distinct vesicles in each gland.
(therefore same location of secretion just at different speeds).

38
Q

Do tears contain glucose or vit A?

A

NO significant amounts.

39
Q

What are five advantages of blinking?

A
  1. spreads tears
  2. foreign body removal
  3. decreases evaporation
  4. spreads mucoid layer
  5. lacrimal pump (squeezes horners muscle around lacrimal sac)
40
Q

what percent of water is lost between blinks?

A

25%

41
Q

What are four disadvantages of lid closure?

A
  1. tearing decreases
  2. stagnation (build up of corneal secretion and debris)
  3. corneal swelling (due to decrease in O2/CO2 exchange)
  4. inflammation (sIGA increases, neutrophils recruited, vessel dilate)
42
Q

ten methods of eye protection?

A
  1. reflex lacrimation
  2. dense corneal nerves
  3. reflex blinking
  4. eye lashes
  5. lacrimal lake
  6. epithelial surface
  7. collagen barrier
  8. intraocular fluids
  9. mucous secreting goblet cells
  10. immune cells from limbal blood vessels
43
Q

lacrimal lake contains lyzozymes that contain what? what do they do?

A

lactoferrin, antibodies, defensines and cytokines all act against foreign bodies that get into tear film

44
Q

inflammatory response releases what cells? which act on nerves to block the release of? which finally results in?

A

releases cytokines.
they act on the nerve to block the release of nt (Ach and NE) and causes the secretion of tears to be blocked. therefore less mucous to trap bacteria, less aqueous, tears become hypotonic and less sIGA.

45
Q

in steady state secretion=?

A

outflow+evaporation

46
Q

common dry eyes is a result of?

A

decreased secretion (not producing enough sero mucin by the lacrimal glands) or increased evaporation (not producing enough oil)

47
Q

uncommon dry eyes is due to?

A

decreased spreading

48
Q

Mechanical causes of dry eye?

A

ectropian (lid turns outward)
entropian (lid turns inward)
exopthalamous (eyes bulging)

49
Q

neural causes of dry eye?

A

Riley Day (reduced nerve effectiveness)

50
Q

Autoimmune causes of dry eye?

A

rimitoid arthritis and Sjogrens

51
Q

environmental causes of dry eye?

A

desert or air conditioning

52
Q

Medications that cause dry eye?

A
  1. anticholinergic (atropine): blocks parasymp system
  2. antihistamine (blcoks receptors for tear production)
  3. beta blockers (timolol or inderol) BP med, blocks symp system which innervates corneal epithelial cells.
53
Q

Idiopathic causes of dry eye?

A

age (older, less tear production)

54
Q

Two common dry eye diseases are?

A
  1. keratitis Sicca: worsens during the day, tears thick and viscous, schirmer test low levels of aqueous
  2. meibomianitis; worse during the morning, tears watery, schirmer test high levels of aqueous.
55
Q

Sjogrens syndrome is what type of disease? results in death of what % of cells in lacrimal gland? is this still enough to produce tears? explain why.

A

autoimmune
50% but still enough cells to produce adequate tears. therefore why do we get dry eye? because immune sys is involved therefore cytokines released which block receptors for tear production therefore not getting proper stimulation. (inflammatory response releases cytokines).

Anatomy (18 decks)

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