POSTERIOR SEGMENT - Neurosensory Retina Flashcards
What is the structure of rod cones from RPE to vitreous?
Outer segment (transductive) –> inner segment (region for maintenance of cellular homeostasis) –> nuclear region (outer nuclear layers) –> transmissive region (outer plexiform/synaptic layer)
Which types of cells are present in the inner nuclear layer? (3)
(1) bipolar neurons
(2) horizontal cells
(3) amacrine cells
What is the difference between the outer segments of rods and cones ? (2)
RODS: cylindrical and contain rhodopsin pigment, made up of vitamin A (night blindness)
CONES: conical and contain iodopsin pigment (colour blindness)
What is the difference in numbers between rods and cones?
rods: 120 million
cones: 5 million
what is the maximum spectral sensitivity of the rod cells?
496nm
What are the main differences between rods and cones? (4)
- Rod discs are enclosed with a cell membrane
- Rod concentration higher in periphery
- Ratio of rod:cone is 20:1
- Peak sensitivity of rods is 496nm, cones is 420 (S), 530 (M) and 560 (L)
What is the most common location for midget ganglion cells and midget bipolar cells?
What is their synapse ratio with cones?
Where do they project to?
Fovea.
1:1 ratio with cones to allow high resolution of the fovea region.
project to the parvocelllular layers of the LGN (P cells)
Which cell is responsible for retinal scar tissue formation?
Astrocytes.
What is the function of muller cells?
the main glial cells of the retina which support in architectural and metabolic functions of the retina.
They contribute to the blood retinal barrier.
What is the structure of astrocytes?
What is the function of astrocytes?
Honeycomb/pattern formation cells peripendicular to the muller cells
Responsible for laying down scar tissue in injured or diseased retina
What is the structure and function of microglia cells?
highly specialised mononuclear phagocytic cells and are first line of defence against pathogen invasion.
What is the maximal spectral sensitivity of the rod?
496nm (blue-green light)
