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Ocular Physiology > Lacrimal System and Conjunctiva part 2 > Flashcards

Lacrimal System and Conjunctiva part 2 Flashcards

1
Q

what is a way to quantitatively test the tears produced

A

a Schirmer’s test

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2
Q

what is the tear meniscus height at the lower lid margin

A

0.75mm

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3
Q

what is a noninvasive way to test the tear film stability

A

with a keratometer (watching the mires to see if they stay stable and clear) about 10 sec

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4
Q

what is an invasive way to measure the tear film stability

A

TBUT (tear break up time) with flourescein (10 sec)

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5
Q

how can you test the ocular surface integrity

A

tissue sampling (impression cytology-counting goblet cells in conjunctiva) or staining techniques

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6
Q

when would you give a Schirmer’s test

A

dry eye or excessive tearing

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7
Q

what are the steps of the Schirmer’s test

A

instill anesthesia and wait a min, wipe excessive tears, place strip on temporal side, wait 5 min, record results

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8
Q

why does the eye need to be numb for a Schirmer’s test

A

otherwise you are testing the reflex tearing, no the basic secretion

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9
Q

why do you place the strip on the temporal side during a Schirmer’s test

A

because the tears drain medially and it will give a false measurement

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10
Q

what is a normal outcome for the Schirmer’s test

A

greater than or equal to 15mm

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11
Q

what is a variation of a normal result of a Schirmer’s test

A

an older individual (over 60) may only have 10mm but not complain of dryness or epiphora

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12
Q

what can affect the outcome of a Schirmer’s test

A

placement of the strip in the eye, age, effect of anesthesia, reflex tearing, and subjective measurement

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13
Q

what is a mild dry eye test result for Schirmer’s

A

9-14 mm

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14
Q

what is a moderate dry eye result for Schirmer’s

A

4-8 mm

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15
Q

what is a severe dry eye result for Schirmer’s

A

less than 4 mm

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16
Q

what is the first stage of secretion of lacrimal gland electrolytes and water

A

the acini cells secrete a fluid that has an electrolyte composition similar to that of plasma

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17
Q

what is the second stage of secretion of lacrimal gland electrolytes and water

A

as the fluid passes through the duct system, the ductal cells modify the fluid by secreting a fluid rich in potassium chloride (KCl)

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18
Q

what drives acinar cell electrolyte secretion

A

a sodium potassium ATPase pumping sodium out of the cell and potassium into the cell

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19
Q

what is the solution called at low fluid rates

A

hypertonic

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20
Q

what is the solution called as the flow rate increases

A

isotonic

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21
Q

how do the ductal cells modify the fluid as it passes through the duct system

A

by secreting a fluid rich in potassium chloride

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22
Q

what ions does the lacrimal gland contain

A

Na+, K+, Cl-, HCO3, Ca2+ and trace amounts of other ions in the same concentration as plasma (except K+ and Cl- which are higher concentrations)

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23
Q

what stimulates the cells to secrete

A

nerves, peptide and steroid hormones present in the blood

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24
Q

what type of nerves innervate the lacrimal gland

A

parasympathetic nerves, sympathetic nerves, and sensory nerves

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25
Q

what specifically do the nerves and peptide hormones stimulate secretion of

A

electrolytes, water and the regulated proteins

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26
Q

what specifically do the steroid hormones stimulate

A

the secretion of the constitutive proteins

27
Q

does stimulation of the sympathetic nervous system result in change in tear secretion

A

no

28
Q

what parasympathetic nerves are responsible for the secretion of tears

A

CN 7 facial nerve

29
Q

what are 5 stimulants that can cause secretion of the lacrimal gland

A

sensory nerves at optic surface, a bright light hitting the optic nerve, acetylcholine and vasoactive intestinal peptide (VIP) and norepinephrine

30
Q

what is the conjunctiva

A

a mucous producing tissue lining the ocular surface (sero-mucous secreting tissue)

31
Q

what part of the external eye is the most immunologically active tissue

A

the conjunctiva

32
Q

how many neutrophils are in a normal conjunctiva

A

6,000

33
Q

how many lymphocytes are in a normal conjunctiva

A

14,000

34
Q

what can provoke conjunctival reactions

A

infections, allergy, and inflammation

35
Q

what are 2 structural changes in allergic reactions of the conjunctiva

A

papillae formation and follicle formation

36
Q

what are papillae

A

areas of conjunctival hypertrophy, contain eosinophils and neutrophils

37
Q

how can you distinguish papillae from follicles

A

papillae have blood vessels in the centers

38
Q

which lid, upper or lower, are papillae normally found in

A

the upper lid (must evert the lid to see them)

39
Q

what are follicles

A

clear, fluid-filled pockets, containing lymphocytes and macrophages

40
Q

what are 2 granulocytes that are not commonly found in normal conjunctiva epithelium

A

eosinophils and basophils

41
Q

what 2 diseases of the conjunctival epithelium have eosinophils and basophils present

A

vernal conjunctivitis and giant papillary conjunctivitis

42
Q

where does a CL usually end up in the eyelid when it becomes displaced

A

in the superior fornix since it has the greatest depth

43
Q

what are the two layers of the conjunctiva

A

epithelium and stroma

44
Q

how many stratified layers are there in the epithelium

A

2-4 stratified epithelial cells

45
Q

when the conjunctival epithelium becomes the corneal epithelium, how many stratified layers does it have

A

5-7, difference begins at the limbus

46
Q

what are located in the palisades of vogt

A

limbal stem cells and increased wing cells

47
Q

what are goblet cells

A

unicellular mucin-secreting glands (holocrine) within conjunctival epithelium

48
Q

which area of the conjunctiva has the most goblet cells

A

fornix and palpebral conjunctiva

49
Q

what does the conjunctival stroma consist of

A

adenoid layer, deep fibrous layer, and a rich network of capillaries

50
Q

why does the conjunctiva need a rich supply of nutrition

A

for regeneration of epithelium and formation of new goblet cells

51
Q

where are the glands of Wolfring located

A

in deep fibrous layer (tarsal plate)

52
Q

where are mast cells found

A

in adenoid layer of conjunctival stroma

53
Q

does the conjunctival epithelium normally have mast cells

A

no they are an inflammatory cell and usually found in the adenoid layer of the stroma

54
Q

when mast cells are present in the conjunctival stroma, how many are there

A

6,000 per cubic millimeter

55
Q

what is the diameter of a mast cell

A

20 micrometers in diameter

56
Q

what are mast cells responsible for

A

immediate hypersensitivity allergic reaction

57
Q

what do mast cells contain

A

several perforated chemical mediators of inflammation, histamine, and heparin

58
Q

what fills the cytoplasm of mast cells

A

30-100 metachromatic granules

59
Q

what happens when mast cells are bound by IgE (allergies)

A

dramatic changes occur in cell membrane and cytoplasm, physical properties change (membrane becomes more permeable to Ca++ ions) and leads to edema

60
Q

which blood vessels are engorged in conjunctival infections

A

superficial posterior vessels

61
Q

which blood vessels are engorged in keratitis or iritis

A

deep ciliary vessels

62
Q

does the conjunctiva have lymphatics

A

yes

63
Q

which way does the temporal lymph drain in the conjunctiva

A

towards lateral extremes of lid, eventually connecting with parotid node

64
Q

where does the medial conjunctival lymph drain

A

to the submandibular lymph glands

Ocular Physiology (6 decks)

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