Retina (Dr. Najeeb and UCL )

Microglia

________ are macrophages which are spread throughout retinal layers and remove cellular debris which have broken down.

Photoreceptor

________ and Bipolar cells have ability to produce graded potentials- these transfer to ganglion cells to produce action potentials.

Rods

________ are generally in periphery, Cones are generally in fovea.

Retinal

________ nerve fibre layer in retina are not myelinated as it is a reflective structure and would cause degradation of the image- → as soon as RNFL hits optic nerve, there is myelination from oligodendrocytes.

Muller cells

________ have foot plates which are a boundary between retina and vitreous (INNER LIMITING MEMBRANE)

Fovea

________ is point of sharpest visual acuity because.

RPE Contains

________ melanosomes and are held to each other by tight junctions.

Astrocytes

________ support neuronal structures, ganglion layer structures and capillary structures-

Cones

________ activate at different wavelengths of light, have 1: 1 connection with bipolar cells so can see more detail in better light settings.

Macula

________ depends on choroidocapiliary diffusion (avascular structure)

Choriocapillaries

________ are vascular circular sinusoids (capillary loops)

Spherule

________ is synaptic terminal.

Cods

________ has pedicule synaptic terminal.

RPE acts

________ as barrier between choriocapillaries and neuro- retina- choriocapillaries give nutrition to outer 5 layers (RPE to outer plexiform layer)

synaptic terminals

Both rods and cones have photoreceptive part facing towards outer retina and have ________ facing inner side of retina (towards bipolar cells)

Bipolar cells

________- multiple rods are connected to one ________ but only one ________ connects to one cone (in fovea)- these behave like dendrites.

Rods

________ and Cones use glutamate as neurotransmitter to bipolar cells> Bipolar cells also are glutaminergic to connect to ganglion cells> Ganglion cells are using glutaminergic to connect to optic tract.

Rods

________ contain rhodopsin on outer segment which has photoreceptive component.

Rods

________ at low lumination can give signals /sensitivity as multiple rods are connected to one bipolar cell, sum of their graded potentials allow action potential to fire from ganglion cell.

Photoreceptor and Bipolar cells have ability to produce graded potentials

these transfer to ganglion cells to produce action potentials

Ganglion cells are main output cells which connect to the optic disc

the current of electrical flow is radial (from outer retina to inner retina) flow is RBG

Horizontal cells connect between photoreceptors connecting laterally and are found in outer plexiform layer

these are usually inhibitory cells and are mediated by GABA

Muller cells originate between inner/outer plexiform later

they fixate rods and cones together through zona adherens (OUTER LIMITING MEMBRANE) and keep inter-photoreceptor fluid and matrix within the layer so doesnt escape beyond through to internal retina

RPE

acts as blood-retinal barrier between choroid

RPE acts as barrier between choriocapillaries and neuro-retina

choriocapillaries give nutrition to outer 5 layers (RPE to outer plexiform layer)

Cones activate at different wavelengths of light, have 1

1 connection with bipolar cells so can see more detail in better light settings

Ganglion cells

some cells have illumination qualities which can send signals independently to hypothalamus (supra-chiasmatic nucleus) via retino-hypothalamic pathway determines circadian rhythm and day/night time

Main visual pathway

Optic nerve -→ optic chiasm -→ lateral geniculate body -→ optic radiations -→ visual cortex

Accodomation/light/pupillary reflex

Optic nerve -→ optic chiasm -→ superior colliculus/pretectal nucleus (degree of illumination of light to midbrain) -→ edinger westphal nucleus -→ parasympathetic fibres to ciliary ganglion -→ ciliaris muscle and sphincter pupillae for light/accomodation reflex

Other pathway

Optic nerve -→ optic chiasm -→ SCN (hypothalamus) -→ control circadian rhythm (with pinneal gland)

1) Photoreceptor cells (Rods/Cones)
2) Epithelial cells
3) Glial cells
4) Neuronal Cells
5) Bipolar Cells

What are the 5 types of cells found in the neuroretina layers?

All nerve fibres/inner retina

What does the central retinal artery supply?

Present in 20% of the population, supplies the retina between macula and optic nerve, including fovea, so in case of CRAO, central vision will somewhat be preserved.

What is the function of the cilio-retinal artery?