Retina (Q3) Flashcards
What does the posterior pole include?
Area of retina bordered by the superior and inferior temporal vasculature and includes the macula and optic nerve head. It is the area evaluated when performing direct ophthalmoscopy
How many microns is a third of a disc diameter? ~0.33 DD = _____
500 microns (know for 2nd year)
What is the range of average optic disc diameters in mm?
1.5mm - 2.2mm
What are the parts of the macula from largest to smallest/outer to inner?
Macula, perifovea, parafovea, fovea, foveola
Which cells are in high number in the parafovea?
Bipolar and ganglion cells
Which part of the macula is ONLY cones?
Foveola
What is the average diameter of the retina from ora to ora?
32mm
Where does the Foveal Avascular Zone receive blood since it is devoid of retinal vessels?
From the choroid
What are the three possible blood supplies to the retina?
Choroid (supplies outer 1/3), central retinal artery (supplies the inner 2/3), and cilioretinal artery (to macular area, seen in 20% of the population)
What are the 10 layers of the retina?
- RPE 2. Photoreceptors 3. External limiting membrane 4. Outer nuclear layer 5. Outer plexiform layer 6. Inner nuclear layer 7. Inner plexiform layer 8. Ganglion cell layer 9. Nerve fiber layer 10. Internal limiting membrane
Which are the first-order neurons in the retina?
Photoreceptors
Which are the second-order neurons in the retina?
Bipolar cells
Which are the third-order neurons in the retina?
Ganglion cells
About how many photoreceptors, bipolar, and ganglion cells are there (each)?
100 million photoreceptors, 36 million bipolar cells, 1 million ganglion cells (retinal pathway is an example of a converging system)
About how many photoreceptors can an RPE cell support?
Each RPE cell interacts with 30-40 photoreceptors
Which of rods or cones are responsible for scotopic and which is responsible for photopic vision?
Rods for scotopic (night vision), cones responsible for photopic (daytime vision)
What is the name of the structure that connects the outer and inner segments of a photoreceptor cell?
Cilium
What are the two regions in the inner segment of a photoreceptor cell?
Myoid and Ellipsoid
What cellular organelles are found in the myoid region of the photoreceptor?
contains ER and Golgi apparatus for protein synthesis
What cellular organelles are found in the ellipsoid region of the photoreceptor?
Contains mitochondria, important for energy for the cell
What are the synaptic terminals of the photoreceptors called for rods, and for cones?
Rods = spherules
Cones = pedicles
What happens to old outer segment discs of the photoreceptor?
Discs are shed throughout the day and phagocytosed by the lysosomes in the RPE cells
About how many millions of cones are there?
4-5 million!
Which type of cone is found less but more consistent in ratio to the other two? S, M, or L?
S, short-wave, blue cones are fewer but have a more constant ratio to the other than M and L to each other have