Retina

Question 1

The retina is derived from the _______

Answer 1

Neural retina

Question 2

The retina has ___ layers

Answer 2

10

RPEOOIIGNI “RPE 2OUTERS 2INNERs GNI”

Question 3

RPE is made up of a single layer of ___ cells

Answer 3

cuboidal cells

Question 4

What is the RPE layer responsible for?

Answer 4

Phagocytosis of the PR outer segments (microvilli located on the apical side of the RPE cells).

Question 5

Undigested material from PR outer segments can accumulate within the RPE which is also known as what?

Answer 5

Lipofuscin

Question 6

What are the 6 major functions of RPE?

Answer 6

1. Phagocytosis of the PR outer segments
2. Transfer of ions, water, and metabolites
3. Vitamin A storage and metabolism - recycle it A (all-trans retinol) and retinoids btw the photoreceptors and the RPE
4. Blood retinal barrier - RPE are tightly linked together by terminal complex that includes ZO, ZA, and MA forming the BRB
5. Absorbs light - absorbs stray light that is not absorbed by the rods and cones
6. Produces growth factors for tissue maintenance

Question 7

How many rods are there?

Answer 7

120 million

Question 8

How man cones are there?

Answer 8

6-8 million

Question 9

Inner Segment of the PRL?

Answer 9

Produces photopigments that are incorporated into discs

Myoid = inner layer of the inner segment - protein synthesis (contain ER and golgi apparatus) “myoid regions makes protein”
Ellipsoid = outer layer of the inner segment - packed w/ mitochondria “energy”
Cilium = connects outer and inner segments of PR

Question 10

Outer Segment of the PRL?

Answer 10

Contain stacks of membranous discs that contains photopigments produced by the inner segments - produce discs that surround the photopigment molecules.
- There are 600-1000 discs per rod and 1000-1200 discs per cone
- Disc membranes are continuous with plasma membrane in cones but are free-floating (NOT continuous with the plasma membrane) in rods

Question 11

Disc photopigments

Answer 11

formed in the inner segment, assembled into discs at the base of the outer segment, and are continually shed at the tip of the outer segment for phagocytosis by the RPE

Question 12

Rods

Answer 12

Scotopic vision
- density is greatest about 5mm (20 degrees) concentrically from the fovea
- contain photopigment rhodopsin - absorbs photon maximally at 507 nm (DOES NOT DETECT COLOR)
- Rods terminate in spherules (cones terminate in pedicles)

Question 13

Cones

Answer 13

Photopic vision
- contain 3 different photopigments (iodopsin)
- cyanolobe (blue): max absorps photons at 426nm
- chlorolabe (green) max absorbs photons at 530 nm
- Erythrolabe (red): max absorbs photons at 557 nm

Question 14

Fovea

Answer 14

5mm temporal and 0.4mm inferior to the center of the optic nerve (sup and nasal to the ONH if viewing w/ 78 and 90D) and contains only cone photoreceptors

Question 15

ELM

Answer 15

does not contain any cells - formed by a band of desmosomal attachments between muller cells and the inner segments of the photoreceptors. It provides structure to the retina and acts as a barrier against large metabolites.

Question 16

ONL

Answer 16

contains the cell bodies of rods and cones

Question 17

OPL

Answer 17

Location of the synapse of rod spherules and cone pedicles and the dendrites of bipolar and horizontal cells
Where rod and cones connect with bipolar and horizontal cells

Question 18

Each rod spherule can synapse to how many rod biploar cell dendrites?

Answer 18

1-4

Horizontal cell dendrites may also connect to rod spherules

Question 19

Cone pedicle

Answer 19

Larger than rod spherule. Can form a synaptic triad that consists of 3 horizontal cell dendrites OR 2 horizontal cell dendrites on either side of 1 biploar cell dendrite within an invagination in the cone pedicle