Week 2 - Lacrimal gland and tears

What are the 2 types of lacrimal gland lobes?

Orbital lobe

Palpebral lobe

What is the difference between the orbital and the palpebral lobe?

Orbital lobe is larger and above the levator aponeurosis

Palpebral lobe is smaller and below the levator aponeurosis

What are the 2 lacrimal gland lobes divided by?

Levator aponeurosis tendon

What are the sizes of the orbital and the palpebral lobe?

Orbital lobe is large

Palpebral lobe is small

Where is the orbital lobe located?

In front lacrimal fossa

Where is the palpebral lobe located?

Near conjunctival surface inside eyelid

Diagram of lacrimal gland

What does serous mean?

Producing / resembling serum

What does tubuloracinar mean?

Gland having branching tubules which end in secretory alveoli

Secretion and transport of exocrine gland via serous gland

What happens in the secretion and transport of exocrine cells such as lacrimal gland?

Serous acini produce protein rich aqueous

Myoepithelial cell contract so move secretion to interlobular duct

Duct further modify composition

Transport fluid to ocular surface

Goblet cell contribute mucin for tear stability

What are goblet cells?

Specialised cells tha tproduce mucins

Located with ducts to stabilism tear film

Diagram of accessory glands

What are the function of tear film?

Maintain smooth refracting surface

Transport metabolic products to epithelium cells

Prevent desiccation of epithelium

Lubricate eyelids

Bactericidal

Pathway for white blood cells

Nutrients

What percentage of tear fluid is lacrimal or accessory gland?

90% lacrimal

10% accessory

What is the resting tear fluid level?

1.5 ml/day

What are the 3 layers of the tear film?

Lipid layer

Aqueous and mucus layer

Mucous layer

What does the lipid layer do?

Inhibit tear evaporation

Protect aqueous layer from polar contamination

What is the function of the mucous layer?

Enable tears to wet epithelium

Maintain stability of tear film during blinking

What are the 2 main cell types in the tear gland?

Secretory and myoepithelium cells

What is the role of myoepithelial cells in the tear gland?

Surrounding acini and produce contractile force to push tears into ducts

What is the role of secretory cells int he tear gland?

Produce tears

How are tears carried out of the tear gland?

Small lumens in lacunae combine form larger ducts, merge into main drainage duct

What do tears mainly contain?

Proteins

Name 4 important components of tears beside proteins?

Lysozomes, lactoferrin, B-lysin, lgA

What is the function of lysozymes in tears?

Fight bacteria

What do lactoferrin do in tears?

Binds iron, reduce bacterial growth

What is the function of lgA in tears?

Provide immune protection against infections

What is the function of B-lysin in tears?

Helps kill bacteria