Retina Flashcards
Why is the optic disk a blind spot
Absence of photoreceptors
Name the 11 retinal layers
ILM- Inner limiting membrane
NFL- Nerve Fibre layer
GCL- ganglion cell layer
IPL- inner plexiform layer
INL- inner nuclear layer
OPL- outer plexiform layer
ONL- outer nuclear layer
OLM- outer limiting membrane
is- (photoreceptors) inner segments
os- (photoreceptors) outer segments
RPE- retinal pigment epithelium
Which of the photoreceptors has a higher number throughout most of the retina
Rods
Which part of the retina contains no rods but many cones
Foveola
What is the fovea
Area of the retina that provides the highest vision acuity
Center of gaze
What is the neural retina
Innermost layer of the retina, which contains the photoreceptor cells
What is the ILM
Inner limiting membrane- a transparent, delicate structure forming the interface between neural retina and vitreous humor
Which are the components of NFL
Axons of ganglion cells
What is the composition of GCL
Ganglion cell BODIES
some amacrine cell bodies
Definition and function of ganglion cells
Final output neurons in the brain
Transmit visual information from the eye to the brain
What is the primary function of IPL
Facilitates the communication between bipolar cells, amacrine cells and ganglion cells
Describe the composition of the IPL
Axons and dendrites
Forms synapses of bipolar cells and amacrine cells WITH ganglion cells
What are the 4 types of cell bodies found in the INL
bipolar
horizontal
Amacrine
Müller cells
What is the composition of the OPL
Synapses of photoreceptor cells with bipolar and horizontal cells
Are axons pre/post synaptic
Presynaptic
Are dentrites pre/post synaptic
Post synaptic
Which layer are the nuclei and cell bodies of rods and cones found
Outer Nuclear Layer
Function of the photoreceptor inner segment
Responsible for metabolic and synthetic activities
Function of the photoreceptors outer segment
Contains visual pigments responsible for light absorption
Function of photoreceptor cilia
Facilitates communication and transport between inner and outer segments
Describe the shape of the cells of RPE
Hexagonal
Simple cuboidal epithelium
Simple columnar epithelium over the fovea
Function of RPE
forms barrier between choroidal blood and neural retina
Absorption of light by melanin
Synthesis of visual pigment chromophore
What pigment is found in RPE and what is its function
Melanin
Absorbed excess lightband reduces light scattering in the eye
Advantage of the macular pigment absorbing blue light
Minimizes chromatic aberration- results in a sharper image
Reduce the amount of high energy blue light reaching the sensitive cells of retina
Describe the differences between the blood supply of outer retina and the inner retina
Outer retina- choroidal blood
Inner retina- blood from blood vessels originating at the optic disk
Based on adhesion and cell types, what are the two types of retina
Neural (neurosensory) retina
Retinal pigment epithelium RPE
What makes up the outer retina
Photoreceptors and RPE
Two main functions of Bruch’s membrane
separating retina and choroid
gaseous, nutrients and waste product exchange
Where is Bruch’s membrane located
Between RPE and choroid
What are the different functions of the apical and basal surfaces of RPE
Apical- phagocytosis of shed outer segments of photoreceptors
Basal- facilitates substance exchange between choroid and retina
Describe how the surface areas of the apical and basal surfaces is increased
Apical- microvilli
Basal- infoldings
Why is the RPE essential for viability and function of photoreceptors (7reasons)
- Transport of nutrients, oxgyen etc between choroid and RPE
- Storage of nutrients
- Transport of nutrients to photoreceptors
- Tight junctions regulate water and molecule flow
- Phagocytosis of shed outer segments
- Recycling of nutrients from phagocytosed os
- Removal of waste
What nutrients are recycled from phagocytosed os
Lipids
Proteins
Vitamin A
3 Functions of omega-3 lipids
Photoreceptor function especially in the os
Anti-inflammatory properties
Protection against oxidative stress due to high metabolic stress in photoreceptors
Why does the macula appear darker on a fundus
Increased concentration of melanin in the RPE
What is the maximal retinal thickness range
349+/- 17 micrometers
