Retinal Synapses And Retinal Aging Flashcards
Big overview of phototrsnaducrtion
Photo receptions
Biochemical cascade (channel closure)
Electronic spread
Slowing of glutamate
Retinal cells and layers
Rods Cods Horizontal cells Bipolar cells Amacrine cells Retinal ganglion cells
What layer is closest to outermost layer of retina
RPE
All the cells in the retina are
Neurons
A junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a NT
Synapse
NT in retina
Glutamate
GABA and glycine
Excitatory NT in retina
Glutamate
Inhibitory NT of retina
GABA and glycine
A change in a cells membrane potential that makes it more negative. It is the opposite of a depolarization. It inhibits AP by increasing the stimulus required to move the membrane potential to the AP threshold
Hyperpolarization
Change within a cell, during which the cell undergoes a shift in electric charge distribution, resulting in less negative charge insid the cell
Depolarization
Light signal transmission
- light evoked signals are transferred onto bipolar and horixaonly cells
- horizaontl cells provide lateral interactions in the OPL
- bipolar cells transfer the light signals into the IPL, onto the amacrine and ganglion cells
- ganglion cells collect the signals of bipolar and machine cells and transmit these signals to the visual centers of the brain
NT of the cone pedicle
Glutamate
Synaptic terminal of cone
Pedicle
When is glutamate high in cones
In darkness
When is glutamate rediced in cone
Reduced by light
Off cone bipolar cells and horizaontla cells ______ by light
Hyperpolarizaed
On cone bipolar cells _____ by light
Depolarized
Off cone bipolar cells transfer signals onto ______ ganglion cells
Off
On cone bipolar cells transfer signal onto _____ ganglion cells
ON
Concomitant with the increase in density, the bipolar cells and ganglion cells dendritic fields become _______ (midget bipolar and midget ganglion cells)
Smaller
The optimized VA in central retina required a high ________ and a low ______
Cone density
Cone-RGC ratio
One cone connected to a midget bipolar cell connected to a midget ganglion cell
Midget system
Synaptic terminal of rods
Spherules
NT of rods
Glutamate
NT of rods
Glutamate
When is glutamate higher in rods
Darkness
When is glutamate lowest in rods
Light
What are the types of rod bipolar cells
There is only one type, ON rod bipolar cells depolarized by light
Tranmission of the rod signal
Rods -on rods bipolar (depolarized) -amacrine cells (depolarized) —glutamate: On cone bipolar cells —
Where do horizaontl cells synapse
Rod spherules and cone pedicle
Horizaontl cells to cone pedicle
Modulated by glutamate release by shifts the activation curves of the cone pedicle Ca2+ channels
Rod spherules and horizontal cells
- modulate the glutamate release by shifts the activation curves of the rod spherules Ca2+ channels
- release of GABA providing inhibition of bipolar cell dendrites
Glutamatergic neurons
Rods, cones,bipolar cells and most ganglion cells
GABAergic and Glycinergic neurons
Horixaonral cells and most amacrine cells
Nerve fibers and aging
Within the optic nerve, they decrease. Optic cup diameter increases
ILM and age
Thickens with age, thus fovea reflex become dimmer
RPE cells and aging
Total number of RPE cells decrease significantly with age; lipofuscin within RPE cells increases and Drusen increases
Retinal atrophy and aging
Increases throughout the retina
Tigroid fundus
Age related retinal atrophy
Pigmentation in RPE/choroid decreases
-visibility of hidden choroidal vessels
-common in ocular albinism
Reticular degeneration
Age related retinal atrophy: peripheral RPE degeneration
Which type of cells plays a role in transmitting cones signal to RGC?
Cone bipolar cells
Which types of cells plays a role in transmitting rod signal to RGC?
Rod bipolar cells and amacrine cells
What changes does ON bipolar cells have with light
Depolarization
What kind of NT do bipolar cells contain?
Glutamate
When the center of RGCs receptive field is exposed to light, which type of RGC is stimulated?
On center RGC
Which finding is likely related to aging changes in retina
Dimmer fovea reflex