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Ocular Physiology Test 1
Aqueous tear secretion
48
Physiology
Professional
09/26/2007

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Term
The lacrimal gland secretes what three things?
Definition
Water, electrolytes, and proteins
Term
The lacrimal gland is part of a functional unit that includes the cornea and conj, accessory lacrimal glands, and meibomian glands that serves to do what?
Definition
Maintain the tear film homeostasis and meet tear fluid demand via neural and hormonal feedback loops
Term
Which lacrimal gland is primarily responsible for normal or basal aqueous secretions? Which is responsible for reflex secretion?
Definition
Primary lacrimal gland
The accessory lacrimal glands
Term
Normal aqueous secretion is about 1.2 microliters/min. What happens to the secretion rate with reflex stimulation?
Definition
It increases 100x
Term
The aqueous layer of the tear film is renewed how often?
Definition
Every 6-7 mins
All production is probably neurogenic/reflex stimulation
Term
Does aqueous production decline or increase with age? Which of the sexes has less production after age 30?
Definition
Decline (50% by age 65)
Females
Term
Does the basal aqueous production vary during the day? When does basal aqueous secretion shut off?
Definition
NO
When you sleep
Term
What is the most common cause of reflex aqueous secretion?
Definition
Stimulation of CN V
-cornea and conj: foreign body, trauma, enviornment
-nasal mucosa
Term
Can emotion or pain cause a stimulus to secrete aqueous?
Definition
YES
Term
Are the accessory lacrimal glands (Krauss and Wolfring) responsible for a large amount of total aqueous secretion?
Definition
NO - Literature varies but around less than 10%
Term
Structurally and functionally, the lacrimal gland is what type of gland?
Definition
Tubuloacinar exocrine gland
Term
The palpebral lobe of the lacrimal gland is located where? Orbital lobe?
Definition
Palpebral lobe is located in the superolateral fornix and can be seen with lid eversion
Orbital lobe is located against the frontal bone in the lacrimal fossa
Term
The lacrimal gland and its acini converge to empty its contents into 12 ducts that open to where?
Definition
Superolateral fornix
Term
What cells lie next to the basal surface of the acini and may act as a pump and also contain contractile protein?
Definition
Myoepithelial
Term
The electrolyte secretions of the lacrimal gland are driven by what?
Definition
Na+K+ATPase pump - sets up an electrochemical gradient
Term
Secretory fluid of acini is similar to what?
Definition
plasma
Term
The movement of water into the lumen is consequence of ion movement. How does water physically enter the lumen?
Definition
Aquaporins
Term
The majority of protein secreted by the lacrimal gland is regulated by neurotransmitters and neuropetides in what process? What other way is protein secreted?
Definition
Exocytosis

Intrinsic or constitutive synthesis/secretion - Made and released immed.
Term
Lacrimal gland protein secretion can also be autonomically regulated via the parasympathetic and sympathetic portion of the reflex arc. The secretory vesicles are stored and releaed upon stimulation of what pathways?
Definition
G=protein or CAMP mediated pathways
Term
Hypertonic tears result from what?
Hypotonic tears result from what?
Definition
Decreased stimulation and/or evaporation
Increased stimulation (more fluid and less dissolved protein)
Term
What is the largest protein present in tears?
Definition
Albumin (60%)
Term
Lactoferrin is a tear specific pre-albumin protein. What is main function?
Definition
It is bacteriostatic, possibly bacteriolytic. It binds to iron ions, which are essential for bacterial metabolism.
Term
Lysozyme is a protein that is considered what? What does it dissolve?
Definition
Bacteriolytic
It dissolves gram positive cell walls
Term
Proteins like epidemalGF, transformingGF, hepatocyteGF, and keratinocyteGF do what to the corneal epithelium?
Definition
Have a role in healing, proliferation, and migration of epithelium
Term
What protein acts on the cell membrane?
Definition
Beta-lysin
Term
What protein is an enzyme in high concentration that comes from corneal epithelium and corneal metabolism?
Definition
Lactate dehydrogenase
Term
What immunoglobulin provides antibody defense in the eye versus infectious agents? Who would have lower amounts of this immunoglobulin?
Definition
IgA
Contact lens wearers
Term
What are the primary and secondary defense steps taken by IgA against infectious agents?
Definition
Primary - Prevent adhesion of microorganisms to ocular surface
Secondary - Induce phagocytosis by PMN's (neutrophils)
Term
The tears are 98.2% what?
Definition
Water
Term
Evidence in morphology and function reveal that which sexes acini are larger?
Definition
Males
Term
Androgens have been shown to have an anti-inflammatory role as well as a cell maintenance role in the lacrimal gland. When do these androgens decrease? What treatment is Dr Connor working on?
Definition
During menopause
Treating dry eye with testosterone cream
Term
Prolactin is a peptide hormone that is synthesized in what cells of the lacrimal gland?
Definition
Acinar cells
Term
The prolactin receptors in the acinar cells of the lacrimal gland serve to do what?
Definition
Modulate cell activity and immune function of the gland
Moderate fluid balance, cell growth, and differentiation
Term
What is an osmole? What is the difference between osmolarity and osmolality?
Definition
An osmole is the amount of substance that dissociates in solution to form 1 mole of osmotically active substance.

Osmolarity = osmols/L
Osmolality = osmols/kg
The two can be used interchangebly because at std pressure and std temp they are the same
Term
The normal osmolality of tears is 304-318 mosm/L. Does the osmolality of tears increase or decrease with contact lens wear?
Definition
It decreases in contact lens wearers initially and then increases back to normal with adaptation.
Term
Dry eye syndrome (DES) is a condtion of increased tear osmolarity due to what two factors?
Definition
Evaporation and reduced aqueous production
Term
According to J Gilbard, MD, what are the four milestones of Dry-Eye Disease?
Definition
Increased tear osmolarity
Decreased goblet cell density and decreased corneal glycogen
Corneal desquamation
Decreased surface glycoproteins
Term
Severe dry eye is called what?
Definition
Keratoconjunctivitis sicca (KCS)
Term
What is the systemic autoimmune disease that pathologically destroys all the bodies moisture producing glands?
Definition
Sjogren's syndrome
Term
What is xerostomia?
Definition
Dry mouth
Term
Can dry eye be an inflammatory condtion?
Definition
YES
Term
The pH of aqueous secretion is about 7.4 with a comfort range from 7.3 to 7.7. If the pH lowers below 6.6 or rises above 7.8, what can happen to the patient?
Definition
Discomfort and increased lacrimation
Term
Injuries tend to _____ alkalinity of the aqueous and bacterial infection seems to do what?
Definition
Increase
Infection causes the pH to lower to 5.2 because of the acidic by-products of bacteria
Term
Which buffer is responsible for keeping the pH of the aqueous secretions close to 7.4?
Definition
Bicarbonate
Term
In the morning, what is the pH of the aqueous secretions?
Definition
It is lower - 6.8
Term
The temperature of the cornea surface is 35 degrees - 36 degrees Celsius. Does it increase or decrease with lid closure? With CL wear?
Definition
Increases
Increases
Term
At what temperature does all metabolism of corneal epithelium cease?
Definition
O degrees Celsius
Term
In general, do anti-histamines and anti-depression drugs increase or decrease tear production? What about marijuana or pilocarpine?
Definition
Decrease
Increase
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