LEC 3 retinal histology B7 Flashcards
LIght energy is transformed into a neural signal
phototransduction
Outer segment of rod photoreceptor is adjacent to what?
RPE
Discs are composed of lipids which is the photopigment of the rod… what is it?
Rhodopsin
WHat is the APEX to APEX relationship? (KNOW IT IMPORTANT)
APEX of RPE and APEX of Photoreceptor outer segments
THis is the photopigment of the rod (only in rod)
-Located in the membrane of the discs (90%) and to a lesser extent in the cell membrane around the cell body (10%)
Rhodopsin
Rhodopsin has peak absorption of light at wavelengths of ~_____?
500 nm
Rod outer segments ______ are shed daily in the early morning. SHed into what space as what? (important concept)
Discs
Shed into Bruch’s membrane as Drusen
Over 100 mutations in the rhodopsin gene have been identified that can lead to inheritance of the rod photoreceptor dystrophy called what?
Retinitis pigmentosa (RP)
Retinal vessels supply what?
Choroid supplies what?
inner retina
outer retina
What is the connecting bridge between outer and inner segment?
Cilium
If cilium doesn’t form properly what happens?
Cant get protein for rhodopsin into the inner segment (can lead to blindness)
Mitochondria are contained in what?
Ellipsoid (is closer to the rod outer segment)
________ region is closer to the cell body of the rod.
Myoid - contains metabolic machinery for synthesizing new discs
The ____________ extends from the inner segment to the cell body
rod outer fiber
The outermost layer is composed of _______
cones
Rod cell bodies are in what layer?
Outer nuclear layer
The synaptic terminal of a rod is called what?
Spherule
-Each spherule has one triad
WHat extends further into the retina than the Rod spherule?
Cone pedicles (slide 25 picture)
How many rod photoreceptors are there?
92-120 million
SCOTOPIC
NO RODS IN FOVEA
ALL RODS CONTAIN RHODOPSIN
What are the 3 opsins, what wavelength do they peak at, and what percent are they seen with? (IMPORTANT)
SHort- Blue- 488 nm (10%)
Middle- Green- 531 nm (60%)
Long- Red- 588nm (30%)
____________ is when one of the three cone photopigments is absent and color is reduced to two dimensions
Dichromacy
Dichromats are categorized into 3 different types, what are they?
Protanopes (absence of L cones)
Deuteranopes (loss of M cones)
Tritanopes (loss of S cones)
Cone cell bodies are a _________ of nuclei in the outermost row of the ______.
Monolayer
Outer nuclear layer
WHat is the neurotransmitter released by cone photoreceptors?
Glutamate
How many cone photoreceptors are in the retina?
5 to 6 mill
10% in the fovea
These modulate the signal from photoreceptors to bipolar cells
-They provide inhibitory feedback to photoreceptors and inhibitory feed-forward to bipolar cells.
Horizontal cells
Where are horizontal cells found? (IMPORTANT)
WHat neurotransmitter do they use?
Outer most row of Inner nuclear layer
GABA- inhibitory
What is the second neuron in the chain between the photoreceptors and the retinal ganglion cells.
Retinal bipolar cells
What are the 2 types of bipolar cells?
Rod bipolar cells
Cone bipolar cells
COne bipolar cells are established into ___ or ___ cells.
ON bipolar cells or OFF bipolar cells
rods are always on
The most widely studied amacrine cell in the retina is the narrow-field ___________ cels.
A2 amacrine
These convey the rod signal to the retinal ganglion cells as rod photoreceptors that have no direct contact with reinal ganglion cells.
A2 amacrine cellls
Rod bipolar cells do not directly connect with what? they have to use what to connect them? (important)
retinal ganclion cells
A2 amacrine cells
What are the radial glial cells of the retina? Creep around everything. Nuclei are located in what?
Muller cells
Inner nuclear layer
These cells are found in the RNFL and the RGCL. Star shaped and send out processed that surround and provide structural support to the vasculature and axons located in the RNFL.
Astrocytes
These are found in small number in the RNFL.
Mobile phagocytes that become highly active and can be found anywhere in the retina under pathological conditions (e.g. trauma injury)
Microglia
