LEC 4 RETINA B7

Question 1

Know the effect of light and dark on retinal neurons.

Answer 1

Light--> 11 Cis retinal
No longer fits into opsin binding site
Changes to all trans retinal
Transducin activated
PDE activated
PDE breaks down c-GMP
Na+ channels close
K+ continues to efflux--> hyperpolarization
Ca+ channels close-->inhibits release of Glutamate
ON bipolar cells depolarize
OFF bipolar cells hyperpolarize

Question 2

Know the effect of light and dark on retinal neurons.

Answer 2

Dark–> c-GMP levels high
c-GMP-gated Na+ channels stay open
Na+ influx creates called dark current
Dark current keeps photoreceptor depolarized at ~40 mV
High density of Na/K pumps allows them to maintain Na and K
Depolarization opens Ca channels
Ca+ essential for vesicles filled with important neurotransmitters to be released at the synaptic cleft

Question 3

This is a diagnostic test that measures the electrical activity generated by neural and non-neural cells in the retina in response to a light stimulus.

Answer 3

Electroretinogram (ERG)

Used to monitor retinal disease

Question 4

Remodeling is sealed by what cells?

Answer 4

Muller cells

Question 5

True/False: The more advanced the remodeling the more likely you can use intervention therapies that restore and preserve the vision.

Answer 5

False: more advanced is bad!

Question 6

What is the most frequent hereditary retinal degeneration among adults?

Answer 6

Retinitis Pigmentosa (RP)
irreversible blindness
gene defect in rods

Question 7

Retinitis Pigmentosa patients can still have vision for many years, how?

Answer 7

Rods start to die off first and cones stay for awhile

Cones still give central vision… (lose peripheral vision)

Question 8

Tharapeutic strategies to restore vision include:

Answer 8

Gene therapy
Viral vectors
Retinal prosthesis
Stem cell therapy
Neurotrophic factors