EXAM 2

Question 1

Lens metabolism before cataract formation

Answer 1

Avascular lens uptakes nutrients/glucose and exports lactic acid via epithelial cells to aque.
Metabolism is 70% anaerobic > ^ lactic acid > ^ NaK ATPase pump stress

Question 2

General pathophysiology of cataracts

Answer 2

Free radicals (superoxide anion O2-) formed with ATP via electron transport chain interrupt cellular processes.
UV light increases risk of DNA mutation, and post translational protein modification.

Question 3

How free radicals effect molecules

Answer 3

With a lone high energy electron, will form covalent bonds with other molecules.

Question 4

Molecules effected by free radicals

Answer 4

Nucleotides of deoxyribonucleic acid
Amino acids of proteins > denatured crystallins
Lipids and fatty acids of plasma membrane

Question 5

Radical effect on DNA

Answer 5

binding to nucleotides > genetic code damage > dysfunctional transcription of messenger rna > translation of dysfunctional proteins

Question 6

Radical effect on proteins

Answer 6

Amino acids of proteins > denatured crystallins
Amino acids of alpha crystalin chaperone > decreased repair of denatured proteins

Question 7

Radical effect on phospholipid bilayer

Answer 7

Lipids and fatty acids of plasma membrane > mitochondria / lens epithelium damage > poor ATP production / cell adhesion > NaK/Ca ATPase pump dysfunction / vacuole formation
Influx of Ca overactivates calpains > damaged protein cleavage > debris buildup

Question 8

How hypoxia occurs with CLs

Answer 8

Receives O2 via diffusion, as it is avascular.
CLs reduce O2 transport rate, leading to hypoxia.

Question 9

Consequence of hypoxia on cornea

Answer 9

lack of O2 > anaerobic metabolism > lactic acid production > increased osmotic gradient > water influx > swelling
Hypoxic conditions also leave cornea vulnerable to infection by pseudomonas a.

Question 10

Consequence of swelling in cornea

Answer 10

Cells are put under stress, unable to maintain homeostasis.
Tight junctions are damaged > cell adhesion lost > apoptosis
Epithelial loss > poor glycolax adhesion > dry eye disease
Stromal hydration > opacity

Question 11

Bacterial opposed to adenoviral conjunctivitis

Answer 11

Rapid onset
Crusting/matting of lids
Mucopurulent discharge
Unilateral usually

Question 12

Adenoviral opposed to bacterial conjunctivitis

Answer 12

Slow onset
History of upper respiratory infection
Watery discharge
Bilateral

Question 13

Innervation of eyelid muscles

Answer 13

Mullers: sympathetic adrenergic, smooth muscle
LPS: Parasympathetic cholinergic nicotinic, smooth muscle