Lacrimal Flashcards
List the components of the secretory (in) system.
Main lacrimal gland
Accessory lacrimal gland (aqueous/water portion)
Meibomian glands (oily portion)
Zeiss glands
Conjunctival goblet cells (mucin)
List the components of the excretory (out) system.
Lacrimal puncta
Lacrimal canaliculi
Lacrimal sac
Nasolacrimal duct (when you cry nose gets stuffy)
Where is the lacrimal gland located in the orbit?
Superotemporal
Sits within depression in frontal bone - fossa of the lacrimal gland
What separates the orbital and palpebral portions of the lacrimal gland?
Aponeurosis of levator
Describe the structure of the lacrimal gland.
Lobular with loose connective tissue
Lobules made up of acini
Network of ducts connect acini and drain into one of 12 excretory ducts which lead to main excretory duct.
What are the components of the lobules (secretory units) of the lacrimal gland?
Central lumen (opening)
Single layer epithelium, make aqueous tears
Basement membrane encloses acinus
Tight junctions between cells
Microvilli line the lumen, increase surface area
Myoepithelial cells (muscle) squeeze lacrimal gland to increase secretion
What do lacrimal glands resemble?
Looks like lifesavers
What supplies blood to and drains the lacrimal gland?
Blood supply via lacrimal artery
Drainage via lacrimal vein
Describe the lymphatics of the lacrimal gland.
Go into conjunctiva and preauricular node
Where are the parasympathetic, sympathetic and sensory nerves supplied from?
Parasympathetic via VII induces tear secretion
Sympathetic controls blood flow and is also involved in the tear
Sensory – lacrimal nerve (V1)
Lacrimal functional unit (LFU)
Integrated system comprising: lacrimal glands, ocular surface (cornea, conjunctiva and meibomian glands) and lids, and the sensory and motor nerves that connect them
Describe the neurostimulant true tear.
Target nasolacrimal reflex
Upregulates parasympathetic activity
Stimulates lacrimal glands to increase tear production
No longer on the market
Describe the structure of tears. (Aqueous, lipid and mucin portions)
Aqueous- main lacrimal gland, accessory lacrimal glands (Krause and Wolfring)
Lipid- meibomian glands
Mucin- goblet cells
What is the function of tears?
Optical (maintain refracting surface and corneal transparency)
Lubrication
Bacteriolysis
Nutrition
What makes up the functional tear film on the ocular surface?
Non-keratinized epithelium of conjunctiva and cornea
Integrity depends on appropriate secretions of tear component, lip apposition, and blink
