Retinal Metabolism - Week 5 Flashcards
(57 cards)
For what processes in the body is ATP usage the highest?
- Dark current
- Neurotransmission
- Ionic Transport
- cGMP, GTP production
What is the metabolic role of NADPH (a reductin)?
is used in:
- chromophore recycling
- membrane synthesis
- as an antioxidant
- membrane integrity + photopigment function
- RNA synthesis/DNA repair
- Vasomotor regulation
What is the metabolic role of Ribose-5-Phosphate?
is used in RNA synthesis
Where in the rod photoreceptor does Rhodopsin de-activation occur?
Outer segment
Where in the rod photoreceptor is rhodopsin found?
Outer segment
Where in the photoreceptor does cGMP synthesis occur?
Outer segment
What is the main role of the photoreceptor inner segment?
Provide ATP for the sodium potassium pump
What is the main role of the photoreceptor outer segment?
Absorption of light
Where in the photoreceptor does phototransduction occur?
Outer segment
Briefly describe the outer segment of a photoreceptor
are actually modified cilia that contain discs filled with opsin (the molecule that absorbs photons), and has voltage gated sodium channels
Where in the photoreceptor does RNA synthesis take place?
Inner segment
What results from impaired transport or defective proteins in the inner segment of the photoreceptor?
Some form of retinal degeneration e.g. RP
What pathway is the primary source of NADPH?
Pentose Phosphate Pathway
Where does glucose get stored?
In the muscle
Note: it does NOT get stored in the brain or retina
What is the main product of Glycolysis?
Precursors that feed kreb cycle (and a little bit of ATP as well)
Briefly describe the Kreb/TCA cycle
a series of enzymatic reactions that loop back on themselves where you are breaking carbon off molecules resulting in the carbons getting shorter as you go around the cycle
What happens when you break a carbon off a molecule in the Kreb/TCA cycle?
you generate a reductin (either NADH or FADH)
How do reductins help generate ATP?
When added to the ETC, reductins can drive an electron gradient to create ATP
What happens to the amino acids produced by the Kreb/TCA cycle?
They become our Neurotransmitters
What 2 things provide vascular supply to the two halves of the iris?
Minor arterial circle - bottom half
Aqueous - top half
Where does the ophthalmic artery originate from?
Internal carotid artery
Where do the the short posterior ciliary arteries enter the eye?
They pierce the sclera posteriorly to enter the choroid layer
Where do the long posterior ciliary arteries enter the eye?
travel medially and laterally along the sides of the optic nerve and past the anterior aspect of the eyeball, piercing the choroid layer
Which part of the retina does the central retinal artery supply?
internal surface of the retina (it pierces close to the optic nerve)
