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Vision - u-szeged.hu · 5 Tears • lubricates and protects •plasma ultrafiltrate, slightly...
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Vision Kaposvári Péter
Transcript of Vision - u-szeged.hu · 5 Tears • lubricates and protects •plasma ultrafiltrate, slightly...
Vision
Kap
osv
ári P
éter
Vision
Kap
osv
ári P
éter
Vision
Kap
osv
ári P
éter
Vision
Kap
osv
ári P
éter
5
Tears
• lubricates and protects
•plasma ultrafiltrate, slightly hypertonic, 1 ml / day
• rinsing out foreign objects
• lyzozym + secretory antibodies + antigenes
• emotional tool
• reflex: afferent: n. V. ------> brainstem (pons)
• efferents: n. VII----> ggl. pterygopalatinum -----> n.V. --> glands
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ggl. pterygopalatinum
Lacrimal gland
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intraocular pressure: ~16 Hgmm, due to the aqueous humor measuring: tonometry •composition: plasma ultrafiltrate
•production: active, epithelial cells in the ciliary body
•drainage: passive, transcellular vesicular transport
role of the pupil
trabecular meshwork
Schlemm chanels
Intraocular pressure
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Tonometry
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Circulation of the aqueous humor
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Glaucoma
Pre
tect
um
III. cranial nerv
Edinger–Westphal nucleus
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n. III.
n. VI.
n. III.
n. III.
n. IV.
n. III.
Accomodation triad
• Lens accomodation • Pupil contraction • convergating eyemovement
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Pupil wide Pupil narrow
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Cornea 39 diopter
Cataracta Normal
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Removing the old lens
Inserting the new lens
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papilla n. optici
fovea
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Cells of the retina
Cells of the retina
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Photoreceptors duplicity theory: receptors for scotopic and photopic vision
scotopic: rods, 500 nm maximum, no colors
photopic: cones, 555 nm, colors
mesopic: at dusk and dawn
cones: 6 million, very dense at the fovea
rods: 120 million, none in the fovea, very dense parafoveal
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Receptor density across the retina R
ecep
tor
den
sity
(1
03/m
m2)
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Dark current
membrane potential~ -30 mV
Glutamate
Dark current
membrane potential~ -30 mV
Glutamate
Nernst equation Goldman–Hodgkin–Katz
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Scotopic, mesopic and photopic vision
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Purkinje shift
• Photopic • Mesopic • Scotopic
Purkinje shift
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Retinal cells: I. receptors (cones and rods) II. bipolar cells III. ganglion cells IV. horizonthal cells (connecting receptors, contrast, color, vision) V. amacrin cells (connecting ganglion and bipolar, cells) VI. Müller glial cells (nutrition, K+ uptake, blood-retina barrier) VII. pigment epithel cells
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light
rods cones
ON and OFF ganglion
RF center
2, 3,5 ipsilateral 1, 4,6 contralateral
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lesions in the visual field
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Retinotopic representation in the visual cortex (cat)
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Retinotopic representation in the visual cortex (human)
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Orientation sensitivity in the pimary visual cortex
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Orientation sensitivity in the pimary visual cortex
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Orientation columns
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orientation direction length
response response response válasz
a látó- kéregben
receptive field light stimulating
inhibitory
stim. stim. stim.
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Hypercolumn in the primary visual cortex
~1000 neurons
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Orientation columns in the primary visual cortex
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Figure 1: A single unit in the left posterior hippocampus activated exclusively by different views of the actress Jennifer Aniston.
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