lecture 4 Flashcards
name the steps in the visual pathway
eye optic nerve optic chiasm optic tract LGN optic radiation visual cortex.
what provides oxygen to the cornea
tear film
what is the cornea made of mostly how are they arranges and why
mostly collagen fibres in parallel to improve trasnsparacy
what is myopia caused by
a long eye (short sighted )
what is hypermetropia caused by
a long eye (long sighted)
what are the structures seen in the iris
pigmented epithelial layer- blocks out light
stroll layer -eye colour
what do midractics do?
dilate the eye
what is the mechsm of action for atropine
Ach antagmoist, so blocks parhasypatic control
what is the aqueous humour formed by
cilliary processes on the edged of the cilliary muscle
what does the aqueous humour drain through?
the trabecular meshwork into the schemes canal
what is glaucoma?
a problem of drainage off aqueous humour, leading to pressure build up in the eye damaging axons and leading to vision loss
how do we treat glaucoma
beta blockers to reduce the formation of aqueous humour
what is the sclera
the protective white outer part of the eye comprised of elastin and collagen
why do humans have more sclera then other species
so we can use eye movements for communication
what is the choroid
a vascular layer that roves oxygen to outer retina especially the fovea
how is the feova related to age related macular degeneration?
abnormal blood vessels grow out of the choroid
what is the retinal pigment epithelium?
pigmented layer for light absorption
what is the purpose of the retinal pigment epithelium?
to reduce oxidative stress form the bbb and phasgotise photoreceptor discs
what are horizontal cells?
interneurons that connect photoreceptors latterly
what do horizontal cells do
allow for forming inhibitory compost of visual feild in order for contrast detection
what do bipolar cells do?
connect photoreceptors to retinal ganglion cells, facilitate sensory processing through horizontal and amacrine cells
how do bipolar cells communicate?
via graded potentials
what do amacrine cells do?
connect bipolar cells laterally, and sense movement to enable motion dectection in the retina
what are retinal ganglion cells?
output cells from the retina
how is the central retina specified for have spatial vision?
long narrow cone outer segments allow for high density packing, obliquely run hence fibres -the axons of cones forms the foveal pit
and ganglion cells heaped up around the fovea
how do photoreceptors work?
depolarised in the dark
disks contain photopigments such as rhodpsin
when these are exposed to light then Na+ channels close
hyperporises the cell
reduced glutamate release
