L05 - Retina 2 Photoreceptors

Question 1

CASE STUDY: JOAN
Age: 45 yo female
-Has trouble seeing at night 
-Many car accidents
-Can read ok

What is her problem? Treatment?

• Black substance around eye
• Pigment under retina migrated into retina

Answer 1

Retinitis pigmentosa - genetic defect in rhodopsin or proteins involved in phototransduction. Tunnel vision (hence decrease in rods, explaining her poor night vision). No treatment yet but has pre clinical model using electrodes under retina to stimulate neurons in retina

Question 2

Describe outer segment of photoR

Answer 2

Jar of coins (discs) having photopigment in between

Question 3

What does inner segment of photoR contain?

Answer 3

Mitochondria, golgi

Question 4

RPE function

Answer 4

• Supply photoR with vitamin A

- Absorb stray light, making it heavily pigmented

Question 5

List from low to high wavelength of pigmented opsins

Answer 5

Blue, Rod, Green, Red

• Red and green cones have little difference in amino acid sequence
• Blue and green cones have MAJOR diff in amino acid sequence

Question 6

_ retinal is in the middle of the___ , light converts it into ____ retinal

Answer 6

11-cis retinal, opsin, All-trans retinal