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Questions and Answers
What is the main function of tears?
What is the main function of tears?
- To express emotions
- To nourish the eye by maintaining a balance of its ingredients (correct)
- To produce proteins like lysozyme and serum albumin
- To protect the eye from dust and other infectious agents
What type of proteins are found in tears?
What type of proteins are found in tears?
- No proteins are present in tears
- Only apolipoproteins H and phospholipase A2
- Only lipophilin C
- Including lysozyme, serum albumin, and other proteins (correct)
What is the name of the factor present in onions that induces tear secretion?
What is the name of the factor present in onions that induces tear secretion?
- Lipophilin C
- Apolipoproteins H
- Phospholipase A2
- Thiopropanal S-oxide (correct)
What is the primary defence agent in tears?
What is the primary defence agent in tears?
What are the three layers of the precorneal (tear) film?
What are the three layers of the precorneal (tear) film?
What is the name of the disorder caused by a defect in tear secretion?
What is the name of the disorder caused by a defect in tear secretion?
Why do females tend to cry more than men?
Why do females tend to cry more than men?
How many types of tear secretion are there?
How many types of tear secretion are there?
What is the function of the lipid layer in the tear film?
What is the function of the lipid layer in the tear film?
What percentage of the total refractory power of the eye is attributed to the tear film?
What percentage of the total refractory power of the eye is attributed to the tear film?
How many square centimeters of area is covered by the tear film?
How many square centimeters of area is covered by the tear film?
What is the thickness of the tear film in micrometers?
What is the thickness of the tear film in micrometers?
Why is crying considered healthy?
Why is crying considered healthy?
How often do women cry on average in a year?
How often do women cry on average in a year?
How many microlitres of tears are secreted per minute?
How many microlitres of tears are secreted per minute?
What is the width of the puncta that drain tears?
What is the width of the puncta that drain tears?
Where are the lacrimal glands situated?
Where are the lacrimal glands situated?
What is the function of lactoferrin?
What is the function of lactoferrin?
What is the primary function of basal tears?
What is the primary function of basal tears?
What is the term for the excessive production of tears due to ocular inflammation?
What is the term for the excessive production of tears due to ocular inflammation?
Which type of tears is produced in response to pain or external stimulus?
Which type of tears is produced in response to pain or external stimulus?
What is the approximate duration of emotional crying in men?
What is the approximate duration of emotional crying in men?
What is the purpose of people crying?
What is the purpose of people crying?
What is the function of lysozyme?
What is the function of lysozyme?
What is the main role of the accessory glands in the eye?
What is the main role of the accessory glands in the eye?
Why does an infant cry without weeping?
Why does an infant cry without weeping?
What physiologically regulates tear secretion?
What physiologically regulates tear secretion?
What is the risk prevented by the accessory glands?
What is the risk prevented by the accessory glands?
What is the effect of cocaine on tear secretion?
What is the effect of cocaine on tear secretion?
What is involved in the regulation of tear secretion?
What is involved in the regulation of tear secretion?
Why are reflex tears stopped even when exposed to strong gases?
Why are reflex tears stopped even when exposed to strong gases?
What is necessary for normal functioning of the eye?
What is necessary for normal functioning of the eye?
What is dry eye caused by?
What is dry eye caused by?
Who is the author of the article 'Tear biochemistry: a review'?
Who is the author of the article 'Tear biochemistry: a review'?
What is the title of the journal where the article 'Diagnostic and Prognostic Features of Sjögren’s Syndrome' is published?
What is the title of the journal where the article 'Diagnostic and Prognostic Features of Sjögren’s Syndrome' is published?
What is the title of the article written by Monica Alves, Rodrigo Nogueira Angerami, and Eduardo Melani Rocha?
What is the title of the article written by Monica Alves, Rodrigo Nogueira Angerami, and Eduardo Melani Rocha?
What is the title of the article written by J.Murube, L.Murube, and A.Murube?
What is the title of the article written by J.Murube, L.Murube, and A.Murube?
Who are the authors of the article 'Evaluation of various risk factors of dry eye'?
Who are the authors of the article 'Evaluation of various risk factors of dry eye'?
What is the journal where the article 'Patho-physiology of lachrymal gland in old age' is published?
What is the journal where the article 'Patho-physiology of lachrymal gland in old age' is published?
Who is the author of the article 'The effects of the tear-film dynamics in healthy subjects and dry eye patients'?
Who is the author of the article 'The effects of the tear-film dynamics in healthy subjects and dry eye patients'?
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Study Notes
Tear Secretion
- Tears are a fluid secreted by the lacrimal glands to moisten and nourish the eyes.
- Tears contain various biologically active substances, including mucin, electrolytes, proteins (e.g., lysozyme, serum albumin), and other chemicals.
- Proteins in tears have important functions, such as defense against infectious agents.
Tear Film
- The precorneal (tear) film has three layers: lipid, aqueous, and mucous.
- The lipid layer acts as a hydrophobic barrier, preventing overflow of tears.
- The aqueous layer contains water and tear proteins, controlling infection and acting as a physiological barrier.
- The mucous layer is hydrophilic, with mucin secreted by the lacrimal glands.
- Tear film break-up time is used to check the stability of the tear film in dry eye and other disorders.
Types of Tears
- There are three types of tear secretion: basal, emotional, and reflex.
- Basal tears are secreted continuously to moisten the eyes.
- Emotional tears are produced in response to emotional stimuli, such as sadness, anger, or frustration.
- Reflex tears are produced in response to pain, external stimuli, or foreign bodies.
Tear Proteins
- Over 60 tear proteins are known, including lactoferrin, antimicrobial molecules, and lysozyme.
- Lactoferrin has antimicrobial activity and is a carrier protein.
- Lysozyme has antibacterial activity.
Tear Secretion Regulation
- Tear secretion is regulated physiologically by cholinergic fibers of the parasympathetic nervous system, sympathetic stimulation to the adrenal gland, certain peptides, and humoral factors.
- Epidermal growth factors also control tear secretion.
Dry Eye
- Dry eye is a symptom caused by low tear secretion, viral infection, excess evaporation of tears, or variation in tear composition.
- Dry eye can lead to disorders such as Sjogren's syndrome and crocodile tears.
Interesting Facts
- On average, women cry 30-64 times a year, while men cry 6-17 times a year.
- The tear secretion rate is 2 microliters per minute or 10 ounces per day.
- Crying is considered healthy due to the presence of certain proteins in tears.
- Lithium carbonate and sodium valproate help decrease tear film break-up time.
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