Chapter 7 - Cornea and External Disease

ashleyr2's version from 2018-01-19 07:36

Section 1

Question Answer
what type of histology cells make up the conjunctiva?nonkeratinized stratified columnar epithelium with goblet cells
what is the plica semilunaris analogous to in animals?nictating membrane in certina animals
whats the caruncle?tissue at medial canthus intermediate between conjunctiva and skin
what does the caruncle contain?accessory dermal appendages
Name the 3 layers of the precorneal tear film?1) lipid (outer layer) 2) aqueous (middle layer) 3) mucin (inner layer)
which 3 glands produce lipids?meibomian (holocrine), zeis (sebaceous), molls (apocrine) glands
whats the importance of lipids in tear film?reduces evaporation
what the importance of aqueous in tear film?provides oxygen to epithelium
what makes up the aqueous in tear film?98% water, 2% protein, pH 7.2, osmolarity 302 mOsm/L
which glands produce aqueous for tear films?lacrimal and accessory lacrimal (exocrine) galnds (krause and wolfring)
whats the basal secretion rate of aqueous in tear films?2 uL/min
which proteins make up the 2% protein in tear films?lysozyme, lactoferrin, IgA, IgG
whats the importance of mucin in tear film?reduces surface tension and allows aqueous tear film to be spread evenly
how much mucin is made per fay?2-3 ml/day
what are the 3 types of mucin?1) secreted mucin (MUC4 and MUC7) produced by lacrimal glands 2) gel-forming mucins (MUC5-AC) produced by conjuncival goblet cells 3) membrane-associated mucins (MUC1 and MUC16)

Section 2

Question Answer
whats the average adult cornea measurements?vertical: 11.5mm, horizontal 12.5mm
whats the cornea horizntal measurements at birth?horizontal: 9.5-10.5mm
at what age does cornea reach adult size?by age 2
whats the central corneal thickness vs peripheral thickness?central thickness: 550 um, peripheral thickness: 1.0mm
what part of the cornea is thinnest?inferotemporal paracentral cornea is the thinnest
what part of the cornea is the thickest?superior paracentral cornea is the thickest
whats the anterior radius of curvature for cornea?7.8mm anteriorly vs. 6.2-6.8mm posteriorly (peripheral cornea is flatter)
whats the power of the cornea: anterior vs. posterior vs totalanterior surface: +49D, posterior surface -6D, total 43D
whats the refractive index of the cornea?1.36 = refractive index of cornea
how thick is the corneal epithelium?50 uM thick (10% of corneal thickness)
is the corneal epithelium hydrophobic or hydrophilic?hydrophobic
what type of energy/metabolism is used in corneal epithelium>aerobic metabolism (accounts for 70% ATP production)
how many days does it take for limbal stem cells to regenerate the corneal epithelium>6-7 days
how many cells thick is the corneal epithelium centrally vs at the limbus?centrally: 4-6 cells thick, at the limbus: 7-10 cells thick