9- Corneal Metabolism And UV Absorption Flashcards Preview

Ocular Physiology > 9- Corneal Metabolism And UV Absorption > Flashcards

Flashcards in 9- Corneal Metabolism And UV Absorption Deck (27):
1

What are some considerations with glucose metabolism in the cornea

Source of glucose
O2 availability

2

What are the active pathways in the glucose metabolism in the cornea

Glycolysis
Krebs
HMP shunt
ETC
Glycogen storage

3

What causes metabolic distress in the cornea

Low O2

4

What does most of the glucose come from?

Aqueous humor

5

What is the minor source of glucose?

Tears
Limbaugh capillaries

6

Where can glucose be derived from?

Glycogen in the EPITHELIUM

7

How many ATP are made in the Krebs and ETC

36 ATP from 1 glucose

8

Where does the epithelium get its oxygen from

Limbus
Pre-corneal tear film (atmosphere)

9

Where does the endothelium gets its O2 from?

Aqueous humor

10

What is aerobic condition

Normal O2 levels

11

What is anaerobic condition

Reduced O2, restricts metabolism

12

What pathway is very important in the cornea

HMP shunt

13

What is the HMP shunt needed for

Regeneration of new corneal epithelial cells that are constantly being produced

14

What does the HMP shunt produce

Intermediates for nucleotide production
And amino acid formation

15

What affect does hypoxia cause?

Pyruvate is converted to lactic acid

16

What affect does lactic acid have?

Diffuses to stroma, causes stress, stromal swelling

17

What affect does stromal swelling have

Halos and rainbows
Increased glare sensitivity
Decreased CS

18

What can cause corneal hypoxia

Contact lenses
Sleeping

19

What is photokeratitis?

Eye damage from UV radiation exposure

20

What affect does low level UV exposure have in the cornea

Inhibit mitosis

21

What effect does medium level UV exposure have in the cornea

Swollen nuclei and cell death

22

What affect does extreme level UV exposure have on the cornea

Sloughing of epithelium

23

At the higher levels of UV damage this molecule contributes to the damage

O2

24

UV damage causes these to form

Thymine dimers

25

How are thymine dimers repaired?

1. Exinuclease cuts on wither side of damage
2. Removal of damaged area
3. Gap filled in by Pol1
4. DNA lipase seals the nick

26

What are DNA repair molecules in eukaryotes

Pol beta and epsilon

27

What is xeroderma pigmentosum?

What are the symptoms?

A rare genetic disorder caused by DNA exinuclease deficiency.


Symptoms: skin damage (increased risk of cancer), eye lid scarring, corneal ulcerations