Metabolic profile of the eye

Question 1

function of the cornea

Answer 1

ion transport, energy production and an antioxidant system

Question 2

where does mitosis occur in the corneal epitheium

Answer 2

basal epithelial cells

Question 3

what is the critical component in the composition of the cornea ?

Answer 3

water (78% of the composition of the cornea)

Question 4

what counter-acts the uptake of water into the cornea ?

Answer 4

active transport of bicarbonate out into aqueous humor

Question 5

the aqueous humor is

Answer 5

hypertonic with respect to the cornea and maintains corneal transparency

Question 6

prolonged wearing of contacts causes hypoxia which results in

Answer 6

increased lactate production, decreased corneal pH and corneal swelling

Question 7

(t/f) the cornea has the HIGHEST rate of flux through the PPP of any tissue (this supports the anti-oxidant system)

Answer 7

True

Question 8

aqueous humor is secreted by

Answer 8

ciliary processes into the posterior chamber

Question 9

where does the aqueous humor drain into

Answer 9

the canal of schlemm

Question 10

function of aqueous humor

Answer 10

brings nutrients to the cornea and the lens and removes metabolic end products from the cornea and the lens

Question 11

increased intraocular pressure results in ?

Answer 11

glaucoma and damage to the optic nerve

Question 12

what causes primary open angle glaucoma

Answer 12

blockage of the drainage canal

Question 13

what causes angle closure glaucoma (narrow angle glaucoma)

Answer 13

outer edge of the iris blocks entrance to canals there are both chronic and acute forms

Question 14

what causes normal tension glaucoma

Answer 14

optic nerve damage depite normal IOP

Question 15

function of the vitreous humor

Answer 15

support function, metabolic carrier for the retina fibrillar network of proteoglycans

Question 16

holds the proteoglycan bridges apart maintaining sparse meshwork

Answer 16

hyaluronic acid

Question 17

symptoms include flashing lights or floaters

Answer 17

posterior vitreous detachment (PVD)

Question 18

PVD is due to

Answer 18

shrinkage and collapse of the vitreous

Question 19

what are to high content molecules in the lens ?

Answer 19

glutathione and cholesterol

Question 20

________is crucial to lens transparency

Answer 20

water

Question 21

energy production in the lens is mainly

Answer 21

anaerobic glycolysis

Question 22

sorbital pathway is important in

Answer 22

lens (metabolizes high glucose and reduces NADPH levels)

Question 23

10% of glucose metabolism in the lens is via

Answer 23

HMP shunt

Question 24

at high glucose concentrations, glucose is converted to

Answer 24

sorbitol

Question 25

the conversion of glucose to sorbitol depletes

Answer 25

NADPH

Question 26

loss of transparency of the lens and aggregation of proteins is charactertici of

Answer 26

cataract formation

Question 27

mechanism of cataract formation

Answer 27

osmotic uptake of water causes crystallins to aggregate increasing light-scattering

Question 28

cataract formation via oxidative damage ?

Answer 28

oxidaation of sugars to dicarbonyl compounds that may cause oxidation of glutathione, protein SH grps, and inhibition of PPP, oxidation of mem. lipids and may impair membraine transport and permeability

Question 29

mechanism of cataract formation via ionizing radiation

Answer 29

decreased glutathionine, increased calcium which promotes 43Kd protein binding to PM, and crystallins bind to protein forming light scattering aggregates

Question 30

senile cataract mechanism

Answer 30

reduced glutathionine levels
modifcation of lens permeability
modification of lens proteins

Question 31

where are the mitochondria lacking

Answer 31

in the greatest area of visual acuity

Question 32

the retina has a high requirement for

Answer 32

protein and phosphilipid biosynthesis (retina is constantly renewed)

Question 33

macular degeneration is associated with what part of the eye

Answer 33

retina

Question 34

dry AMD

Answer 34

slow progression

cells of macula break down (deposits of drusen)

Question 35

wet AMD

Answer 35

rapid progression

blood vessels grow beneath macula-fragile and leak