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Ocular Physiology > The Lacrimal System Part 1 > Flashcards

The Lacrimal System Part 1 Flashcards

1
Q

The primary provider of the aqueous secretory component to the tear film is called what?

A

The main lacrimal gland.

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2
Q

Where is the main lacrimal gland located?

A

Lacrimal fossa.

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3
Q

What are the two parts of the lacrimal gland?

A

Orbital and palpebral lobe.

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4
Q

What separates the lacrimal gland into two lobes?

A

Lateral horn of the levator and extensions of Mueller’s muscle.

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5
Q

What color is the lacrimal gland when the upper lid is everted?

A

Pinkish gray appearance.

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6
Q

The main lacrimal gland is surrounded by ______________ and is made up of many ______ that drain into progressively ___________.

A

Connective tissue; acini; larger tubules.

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7
Q

What type of cells are acini?

A

Myoepithelial cell layer.

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8
Q

Why is it important that acini are myoepithelial cells?

A

Lacrimal gland requires muscle movement to allow contents to be drained.

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9
Q

When does the lacrimal gland start developing?

A

Near third month of fetal life but not functional until after birth.

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10
Q

When do newborn babies start producing tears?

A

2 weeks after born. (May be as long as 2 months).

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11
Q

What are the two accessory lacrimal glands?

A

Glands of Krause and Wolfring.

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12
Q

What is an accessory lacrimal gland?

A

Secondary provider of the aqueous secretory component to the tear film.

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13
Q

Where is the Wolfring gland located?

A

Tarsal plate of eyelid.

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14
Q

Where is the gland of Krause located?

A

Conjunctival fornix.

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15
Q

The arterial supply to the lacrimal gland comes from where?

A

The lacrimal branch of the ophthalmic artery, a branch of the infraorbital artery, the recurrent meningeal artery.

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16
Q

The lacrimal gland is innervated by which cranial nerve?

A

Lacrimal branch of the trigeminal nerve V.

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17
Q

How many layers does the tear layer have? What does the tear film consists of? What structure of the eye does the tear film cover?

A
  1. Mucous, aqueous, and oily layer. Cornea and conjunctiva.
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18
Q

The primary source of ________ to cornea is from the tear film.

A

Oxygen.

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19
Q

Why does cornea need oxygen?

A

Cornea is avascular, doesn’t have its own blood supply.

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20
Q

What does the tear film contain to help protect the cornea and conjunctiva from infection?

A

Antibacterial proteins.

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21
Q

The outermost lipid layer of the tear film is made and secreted by what?

A

Modified sebaceous glands, meibomian glands and gland of Zeiss (oil layer of fair follicle).

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22
Q

The middle aqueous layer of the tear film is made and secreted by what?

A

Lacrimal gland, gland of Krause and Wolfring.

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23
Q

The innermost mucous layer of the tear film is made and secreted by what?

A

Goblet cells, epithelial cells, and very little from the lacrimal gland.

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24
Q

How thick is the lipid layer?

A

0.1 microns.

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25
Q

How thick is the aqueous layer?

A

7 microns.

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26
Q

How thick is the mucous layer?

A

0.05 microns.

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27
Q

What is main contributor to the tear film?

A

Lacrimal gland.

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28
Q

How many meibomian glands are in the upper lid?

A

30-40 glands.

29
Q

How many meibomian glands are in the lower lid?

A

20-30 glands.

30
Q

What helps release the meibomian material from the ducts onto the tear film?

A

Blink.

31
Q

Discharge secretion contains the entire secreting cells laden with the secretory material is known as what?

A

Holocrine secretion.

32
Q

How is the meibomian gland regulated?

A

Not sure, but thought by controlling he rate of lipid synthesis in the endoplasmic reticulum and by regulating the rupture of alveolar cells.

33
Q

What are some possible ways meibomian glands are regulated?

A

Androgen sex steroids (may regulate synthesis and secretion), neurotransmitters (from nerves surrounding the acini).

34
Q

What are two possible ways the meibomian glands are neural regulated?

A

VIP, and NPY.

Vasoactive intestinal peptide, neuropeptide Y

35
Q

Low order of tear secretion is during what?

A

Normal activities.

36
Q

High order of tear secretion is during what?

A

Reflex tearing or crying.

37
Q

Not only does the lacrimal gland secrete aqueous solution into the tear film, but they also secrete what?

A

Mixture of nutrients, growth factors, glycoproteins and immunoglobulins in an isotonic Na+-, K+-, and Cl- rich solution.

38
Q

What is the predominant cell type in lacrimal glands?

A

Acinar cells.

39
Q

The final tear aqueous fluid is a mixture of what?

A

NaCl-rich fluid.

40
Q

Essentially, what three things make up the aqueous layer?

A

Proteins, electrolytes, and water.

41
Q

What is included in the protein part of the aqueous layer?

A

Lysozyme, lactoferrin, lipocalin, immunoglobulin A, growth factors, interleukins.

42
Q

Lacrimal gland dysfunction may indicate dry eye condition often termed as what?

A

Sjorgren’s Syndrome.

43
Q

Severely dry eyes may lose what in their cornea?

A

Transparency.

44
Q

Corneal and conjunctival epithelia are minor contributors to the aqueous humor. What do they release? What do they not release?

A

Electrolytes and water. Proteins.

45
Q

Primary source of the mucous layer of the tear film is called what?

A

Goblet cells.

46
Q

What is inside the mucous layer?

A

Mucins.

47
Q

What does mucin contain?

A

Collection of large heterogenous glycoproteins and at least 50% carbohydrates by mass.

48
Q

Mucous layer is secreted by activation of what?

A

Sensory nerves.

49
Q

What is the secondary source of mucous layer?

A

Stratified squamous cells of the conjunctiva and corneal epithelia.

50
Q

The opening on the medial portion of each eyelid where tears drain is called what?

A

Punctum.

51
Q

The superior and inferior canaliculi are lined with what type of cell?

A

Striatified squamous epithelium.

52
Q

The superior and inferior canaliculi are surrounded by which muscle?

A

Orbicularis oculi.

53
Q

What percentage of people have the common canaliculus?

A

90%.

54
Q

Nasolacrimal sac has a structure present at the opening of the duct into the nose. What is this structure called?

A

Hasner’s valve.

55
Q

What percentage of tears is lost to evaporation?

A

10-25%.

56
Q

Due to gravity, which punctum drains 4 times more tears than the contralateral punctum.

A

Inferior punctum.

57
Q

What can be used to allow tears to remain in our eyes?

A

Punctal plug.

58
Q

What theory states that the contraction of the pretarsal orbicularis muscle fibers during eyelid closure compresses and shortens the canaliculi to allow tear to flow towards the lacrimal sac.

A

Lacrimal Pump Theory.

59
Q

Why does facial paralysis lead to epiphora (excessive tearing down face)?

A

Orbicularis muscle doesn’t do its job, lacrimal pump theory doesn’t work, shortening of the canaliculi doesn’t occur so tear never flows through the lacrimal sac.

60
Q

What is the volume of tears drained per blink?

A

2.0 ml.

61
Q

True or False: 5 blinks transports more tears than 1 min of basic secretion.

A

False. One blink.

62
Q

The lacrimal excretory system usually functions below capacity or above capacity?

A

Below capacity.

63
Q

What does the Doane Blink model emphasis?

A

Compression of the canaliculi and to lesser extend, nasolacrimal sac during eyelid closure.

64
Q

When does siphoning by the lacrimal sac occur?

A

During relaxation of the blink.

65
Q

does gravity increase or decrease lacrimal drainage?

A

Increase.

66
Q

What three things can lead to insufficient tear layers?

A

Sjogren’s syndrome, increase in age, compromised innervation.

67
Q

What are causes of dry eye complaints in contact lens wearers?

A

Insufficient tears, poor quality tears, incomplete blinking, infrequent blinking when focusing, blepharitis (inflammation of eyelid).

68
Q

Why is Jones test necessary?

A

To see if patient has a blockage in the canaliculi. See is patients has epiphora.

69
Q

What is the second part of Jones test for?

A

To see where obstruction occurred.

Ocular Physiology (6 decks)

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