Image formation & processing Flashcards
What are the two layers of the retina?
Neurosensory retina - inner layer.
Retinal pigment epithelium - outer layer.
What does the outer limiting membrane contain?
Muller cells - glial cells that support neurones.
What does the outer plexiform layer contain?
Synapses of photoreceptor cells & bipolar cells.
What does the inner nuclear layer contain?
Cell bodies of bipolar cells.
What does the inner plexiform layer contain?
Synapses of bipolar cells & ganglion cells.
What does the ganglion cell layer contain?
Cell bodies of ganglion cells.
What does the nerve fibre layer contain?
Axons of ganglion cells - form the optic nerve.
What does the inner limiting membrane contain?
Terminals of muller cells.
Also forms the basement membrane.
What is the choroid & what does it contain?
Vascular layer of the eye between the sclera & retina.
Contains the choricocapillaris - blood supply to the outer retina.
What happens to photoreceptor cells in the dark?
They are “turned on”.
No photons are absorbed by rhodopsin > cGMP can activate cGMP-gated Na+ channels > depolarisation > release of glycine onto bipolar cells > inhibition of bipolar cells.
What happens to photoreceptor cells in the light?
They are “turned off”.
Photons are absorbed by rhodopsin > transformation from 11-cis to 11-trans retinal > activation of opsin > activation of transducin > activation of PDE > PDE converts cGMP into GMP > inactivation of cGMP-gated Na+ channels > hyperpolarisation > activation of bipolar cells > activation of ganglion cells > neural transduction to the visual cortex.
What are the highest concentration of cone cells found & why?
In the fovea.
Allows for high acuity central vision.
What pigments sense colour?
Opsins.
What does a deficiency in opsin production result in?
Dischromotopsia.
What is red colour weakness known as?
Protanopia.
